/*
  Copyright(C) 2009-2018  Brazil
  Copyright(C) 2018-2022  Sutou Kouhei <kou@clear-code.com>

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License version 2.1 as published by the Free Software Foundation.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/

#include "grn.h"

#include <fcntl.h>
#include <float.h>
#include <math.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>

#ifdef WIN32
# include <io.h>
# include <share.h>
#endif /* WIN32 */

#include "grn_ii.h"
#include "grn_ii_select_cursor.h"
#include "grn_ctx_impl.h"
#include "grn_table.h"
#include "grn_token_cursor.h"
#include "grn_pat.h"
#include "grn_db.h"
#include "grn_obj.h"
#include "grn_output.h"
#include "grn_report.h"
#include "grn_scorer.h"
#include "grn_util.h"
#include "grn_posting.h"
#include "grn_vector.h"
#include "grn_selector.h"
#include "grn_wal.h"

#ifdef GRN_SUPPORT_REGEXP
# define GRN_II_SELECT_ENABLE_SEQUENTIAL_SEARCH_TEXT
#endif

#ifdef GRN_II_SELECT_ENABLE_SEQUENTIAL_SEARCH_TEXT
# include "grn_string.h"
# include "grn_onigmo.h"
#endif

/* P is for physical? */
#define MAX_PSEG                 0x20000
#define MAX_PSEG_SMALL           0x00200
/* MAX_PSEG_MEDIUM has enough space for the following source:
 *   * Single source.
 *   * Source is a fixed size column or _key of a table.
 *   * Source column is a scalar column.
 *   * Lexicon doesn't have tokenizer.
 */
#define MAX_PSEG_MEDIUM          0x10000
#define MAX_PSEG_LARGE           0x40000
#define S_CHUNK                  (1 << GRN_II_W_CHUNK)
#define W_SEGMENT                18
#define S_SEGMENT                (1 << W_SEGMENT)
#define W_ARRAY_ELEMENT          3
#define S_ARRAY_ELEMENT          (1 << W_ARRAY_ELEMENT)
#define W_ARRAY                  (W_SEGMENT - W_ARRAY_ELEMENT)
#define ARRAY_MASK_IN_A_SEGMENT  ((1 << W_ARRAY) - 1)

#define S_GARBAGE                (1<<12)

#define CHUNK_SPLIT              0x80000000
#define CHUNK_SPLIT_THRESHOLD    0x60000

#define MAX_N_ELEMENTS           5

#ifndef S_IRUSR
# define S_IRUSR 0400
#endif /* S_IRUSR */
#ifndef S_IWUSR
# define S_IWUSR 0200
#endif /* S_IWUSR */

static grn_bool grn_ii_cursor_set_min_enable = GRN_TRUE;
static double grn_ii_select_too_many_index_match_ratio_text = -1;
static double grn_ii_select_too_many_index_match_ratio_reference = -1;
static double grn_ii_estimate_size_for_query_reduce_ratio = 0.9;
static grn_bool grn_ii_overlap_token_skip_enable = GRN_FALSE;
static uint32_t grn_ii_builder_block_threshold_force = 0;
static uint32_t grn_ii_max_n_segments_small = MAX_PSEG_SMALL;
static uint32_t grn_ii_max_n_chunks_small = GRN_II_MAX_CHUNK_SMALL;
static int64_t grn_ii_reduce_expire_threshold = 32;
static grn_bool grn_ii_dump_index_source_on_merge = GRN_FALSE;

void
grn_ii_init_from_env(void)
{
  {
    char grn_ii_cursor_set_min_enable_env[GRN_ENV_BUFFER_SIZE];
    grn_getenv("GRN_II_CURSOR_SET_MIN_ENABLE",
               grn_ii_cursor_set_min_enable_env,
               GRN_ENV_BUFFER_SIZE);
    if (strcmp(grn_ii_cursor_set_min_enable_env, "no") == 0) {
      grn_ii_cursor_set_min_enable = GRN_FALSE;
    } else {
      grn_ii_cursor_set_min_enable = GRN_TRUE;
    }
  }

  {
    char grn_ii_select_too_many_index_match_ratio_text_env[GRN_ENV_BUFFER_SIZE];
    grn_getenv("GRN_II_SELECT_TOO_MANY_INDEX_MATCH_RATIO_TEXT",
               grn_ii_select_too_many_index_match_ratio_text_env,
               GRN_ENV_BUFFER_SIZE);
    if (grn_ii_select_too_many_index_match_ratio_text_env[0]) {
      grn_ii_select_too_many_index_match_ratio_text =
        atof(grn_ii_select_too_many_index_match_ratio_text_env);
    } else {
      /* For backward compatibility. */
      char grn_ii_select_too_many_index_match_ratio_env[GRN_ENV_BUFFER_SIZE];
      grn_getenv("GRN_II_SELECT_TOO_MANY_INDEX_MATCH_RATIO",
                 grn_ii_select_too_many_index_match_ratio_env,
                 GRN_ENV_BUFFER_SIZE);
      if (grn_ii_select_too_many_index_match_ratio_env[0]) {
        grn_ii_select_too_many_index_match_ratio_text =
          atof(grn_ii_select_too_many_index_match_ratio_env);
      }
    }
  }

  {
    char grn_ii_select_too_many_index_match_ratio_reference_env[GRN_ENV_BUFFER_SIZE];
    grn_getenv("GRN_II_SELECT_TOO_MANY_INDEX_MATCH_RATIO_REFERENCE",
               grn_ii_select_too_many_index_match_ratio_reference_env,
               GRN_ENV_BUFFER_SIZE);
    if (grn_ii_select_too_many_index_match_ratio_reference_env[0]) {
      grn_ii_select_too_many_index_match_ratio_reference =
        atof(grn_ii_select_too_many_index_match_ratio_reference_env);
    }
  }

  {
    char grn_ii_estimate_size_for_query_reduce_ratio_env[GRN_ENV_BUFFER_SIZE];
    grn_getenv("GRN_II_ESTIMATE_SIZE_FOR_QUERY_REDUCE_RATIO",
               grn_ii_estimate_size_for_query_reduce_ratio_env,
               GRN_ENV_BUFFER_SIZE);
    if (grn_ii_estimate_size_for_query_reduce_ratio_env[0]) {
      grn_ii_estimate_size_for_query_reduce_ratio =
        atof(grn_ii_estimate_size_for_query_reduce_ratio_env);
    }
  }

  {
    char grn_ii_overlap_token_skip_enable_env[GRN_ENV_BUFFER_SIZE];
    grn_getenv("GRN_II_OVERLAP_TOKEN_SKIP_ENABLE",
               grn_ii_overlap_token_skip_enable_env,
               GRN_ENV_BUFFER_SIZE);
    if (strcmp(grn_ii_overlap_token_skip_enable_env, "yes") == 0) {
      grn_ii_overlap_token_skip_enable = GRN_TRUE;
    } else {
      grn_ii_overlap_token_skip_enable = GRN_FALSE;
    }
  }

  {
    char grn_ii_builder_block_threshold_env[GRN_ENV_BUFFER_SIZE];
    grn_getenv("GRN_II_BUILDER_BLOCK_THRESHOLD",
               grn_ii_builder_block_threshold_env,
               GRN_ENV_BUFFER_SIZE);
    if (grn_ii_builder_block_threshold_env[0]) {
      grn_ii_builder_block_threshold_force =
        grn_atoui(grn_ii_builder_block_threshold_env,
                  grn_ii_builder_block_threshold_env +
                  strlen(grn_ii_builder_block_threshold_env),
                  NULL);
    } else {
      grn_ii_builder_block_threshold_force = 0;
    }
  }

  {
    char grn_ii_max_n_segments_small_env[GRN_ENV_BUFFER_SIZE];
    grn_getenv("GRN_II_MAX_N_SEGMENTS_SMALL",
               grn_ii_max_n_segments_small_env,
               GRN_ENV_BUFFER_SIZE);
    if (grn_ii_max_n_segments_small_env[0]) {
      grn_ii_max_n_segments_small =
        grn_atoui(grn_ii_max_n_segments_small_env,
                  grn_ii_max_n_segments_small_env +
                  strlen(grn_ii_max_n_segments_small_env),
                  NULL);
      if (grn_ii_max_n_segments_small > MAX_PSEG) {
        grn_ii_max_n_segments_small = MAX_PSEG;
      }
    }
  }

  {
    char grn_ii_max_n_chunks_small_env[GRN_ENV_BUFFER_SIZE];
    grn_getenv("GRN_II_MAX_N_CHUNKS_SMALL",
               grn_ii_max_n_chunks_small_env,
               GRN_ENV_BUFFER_SIZE);
    if (grn_ii_max_n_chunks_small_env[0]) {
      grn_ii_max_n_chunks_small =
        grn_atoui(grn_ii_max_n_chunks_small_env,
                  grn_ii_max_n_chunks_small_env +
                  strlen(grn_ii_max_n_chunks_small_env),
                  NULL);
      if (grn_ii_max_n_chunks_small > GRN_II_MAX_CHUNK) {
        grn_ii_max_n_chunks_small = GRN_II_MAX_CHUNK;
      }
    }
  }

  {
    char grn_ii_reduce_expire_threshold_env[GRN_ENV_BUFFER_SIZE];
    grn_getenv("GRN_II_REDUCE_EXPIRE_THRESHOLD",
               grn_ii_reduce_expire_threshold_env,
               GRN_ENV_BUFFER_SIZE);
    if (grn_ii_reduce_expire_threshold_env[0]) {
      grn_ii_reduce_expire_threshold =
        grn_atoll(grn_ii_reduce_expire_threshold_env,
                  grn_ii_reduce_expire_threshold_env +
                  strlen(grn_ii_reduce_expire_threshold_env),
                  NULL);
    }
  }

  {
    char grn_ii_dump_index_source_on_merge_env[GRN_ENV_BUFFER_SIZE];
    grn_getenv("GRN_II_DUMP_INDEX_SOURCE_ON_MERGE",
               grn_ii_dump_index_source_on_merge_env,
               GRN_ENV_BUFFER_SIZE);
    if (strcmp(grn_ii_dump_index_source_on_merge_env, "yes") == 0) {
      grn_ii_dump_index_source_on_merge = GRN_TRUE;
    } else {
      grn_ii_dump_index_source_on_merge = GRN_FALSE;
    }
  }
}

void
grn_ii_cursor_set_min_enable_set(grn_bool enable)
{
  grn_ii_cursor_set_min_enable = enable;
}

grn_bool
grn_ii_cursor_set_min_enable_get(void)
{
  return grn_ii_cursor_set_min_enable;
}

static void
grn_ii_get_term(grn_ctx *ctx, grn_ii *ii, grn_id tid, grn_obj *term)
{
  if (tid == GRN_ID_NIL) {
    return;
  }

  char key[GRN_TABLE_MAX_KEY_SIZE];
  int key_size;
  key_size = grn_table_get_key(ctx, ii->lexicon, tid,
                               key, GRN_TABLE_MAX_KEY_SIZE);
  if (key_size != 0) {
    grn_obj key_buf;
    GRN_OBJ_INIT(&key_buf,
                 GRN_BULK,
                 GRN_OBJ_DO_SHALLOW_COPY,
                 ii->lexicon->header.domain);
    GRN_TEXT_SET(ctx, &key_buf, key, key_size);
    grn_inspect(ctx, term, &key_buf);
    GRN_OBJ_FIN(ctx, &key_buf);
  }
}

/* segment */

grn_inline static uint32_t
grn_ii_get_array_pseg_inline(grn_ii *ii,
                             uint32_t lseg)
{
  if (lseg < GRN_II_MAX_LSEG) {
    return ii->header.common->ainfo[lseg];
  } else {
    return ii->header.large->ainfo_extend[lseg - GRN_II_MAX_LSEG];
  }
}

grn_inline static void
grn_ii_set_array_pseg_inline(grn_ii *ii,
                             uint32_t lseg,
                             uint32_t pseg)
{
  if (lseg < GRN_II_MAX_LSEG) {
    ii->header.common->ainfo[lseg] = pseg;
  } else {
    ii->header.large->ainfo_extend[lseg - GRN_II_MAX_LSEG] = pseg;
  }
}

grn_inline static uint32_t
grn_ii_get_buffer_pseg_inline(grn_ii *ii,
                              uint32_t lseg)
{
  if (lseg < GRN_II_MAX_LSEG) {
    return ii->header.common->binfo[lseg];
  } else {
    return ii->header.large->binfo_extend[lseg - GRN_II_MAX_LSEG];
  }
}

grn_inline static uint32_t *
grn_ii_get_buffer_pseg_address_inline(grn_ii *ii,
                                      uint32_t lseg)
{
  if (lseg < GRN_II_MAX_LSEG) {
    return &(ii->header.common->binfo[lseg]);
  } else {
    return &(ii->header.large->binfo_extend[lseg - GRN_II_MAX_LSEG]);
  }
}

grn_inline static void
grn_ii_set_buffer_pseg_inline(grn_ii *ii,
                              uint32_t lseg,
                              uint32_t pseg)
{
  if (lseg < GRN_II_MAX_LSEG) {
    ii->header.common->binfo[lseg] = pseg;
  } else {
    ii->header.large->binfo_extend[lseg - GRN_II_MAX_LSEG] = pseg;
  }
}

grn_inline static uint32_t
grn_ii_n_logical_segments_inline(grn_ii *ii)
{
  if (ii->header.common->flags & GRN_OBJ_INDEX_LARGE) {
    return GRN_II_MAX_LSEG + GRN_II_MAX_LSEG_EXTEND;
  } else {
    return GRN_II_MAX_LSEG;
  }
}

grn_inline static uint32_t
segment_get(grn_ctx *ctx, grn_ii *ii)
{
  grn_ii_header_common *header = ii->header.common;
  uint32_t pseg;
  if (header->bgqtail == ((header->bgqhead + 1) & (GRN_II_BGQSIZE - 1))) {
    pseg = header->bgqbody[header->bgqtail];
    header->bgqtail = (header->bgqtail + 1) & (GRN_II_BGQSIZE - 1);
  } else {
    pseg = header->pnext;
    if (!pseg) {
      uint32_t i;
      uint32_t pmax = 0;
      char *used;
      const uint32_t max_segment = ii->seg->header->max_segment;
      used = GRN_CALLOC(max_segment);
      if (!used) { return max_segment; }
      const uint32_t n_logical_segments = grn_ii_n_logical_segments_inline(ii);
      for (i = 0; i < n_logical_segments; i++) {
        pseg = grn_ii_get_array_pseg_inline(ii, i);
        if (pseg != GRN_II_PSEG_NOT_ASSIGNED) {
          if (pseg > pmax) { pmax = pseg; }
          used[pseg] = 1;
        }
        pseg = grn_ii_get_buffer_pseg_inline(ii, i);
        if (pseg != GRN_II_PSEG_NOT_ASSIGNED) {
          if (pseg > pmax) { pmax = pseg; }
          used[pseg] = 1;
        }
      }
      for (pseg = 0; pseg < max_segment && used[pseg]; pseg++) ;
      GRN_FREE(used);
      header->pnext = pmax + 1;
    } else if (ii->header.common->pnext < ii->seg->header->max_segment) {
      header->pnext++;
    }
  }
  return pseg;
}

grn_inline static grn_rc
segment_get_clear(grn_ctx *ctx, grn_ii *ii, uint32_t *pseg)
{
  uint32_t seg = segment_get(ctx, ii);
  if (seg < ii->seg->header->max_segment) {
    void *p = grn_io_seg_ref(ctx, ii->seg, seg);
    if (!p) { return GRN_NO_MEMORY_AVAILABLE; }
    memset(p, 0, S_SEGMENT);
    grn_io_seg_unref(ctx, ii->seg, seg);
    *pseg = seg;
    return GRN_SUCCESS;
  } else {
    return GRN_NO_MEMORY_AVAILABLE;
  }
}

grn_inline static grn_rc
buffer_segment_new(grn_ctx *ctx, grn_ii *ii, uint32_t *segno)
{
  uint32_t lseg, pseg;
  if (*segno == GRN_II_PSEG_NOT_ASSIGNED) {
    const uint32_t n_logical_segments = grn_ii_n_logical_segments_inline(ii);
    for (lseg = 0; lseg < n_logical_segments; lseg++) {
      if (grn_ii_get_buffer_pseg_inline(ii, lseg) == GRN_II_PSEG_NOT_ASSIGNED) {
        break;
      }
    }
    if (lseg == n_logical_segments) {
      return GRN_NO_MEMORY_AVAILABLE;
    }
    *segno = lseg;
  } else {
    if (grn_ii_get_buffer_pseg_inline(ii, *segno) != GRN_II_PSEG_NOT_ASSIGNED) {
      return GRN_INVALID_ARGUMENT;
    }
    lseg = *segno;
  }
  pseg = segment_get(ctx, ii);
  if (pseg < ii->seg->header->max_segment) {
    grn_ii_set_buffer_pseg_inline(ii, lseg, pseg);
    if (lseg >= ii->header.common->bmax) {
      ii->header.common->bmax = lseg + 1;
    }
    return GRN_SUCCESS;
  } else {
    return GRN_NO_MEMORY_AVAILABLE;
  }
}

static grn_rc
buffer_segment_reserve(grn_ctx *ctx, grn_ii *ii,
                       uint32_t *lseg0, uint32_t *pseg0,
                       uint32_t *lseg1, uint32_t *pseg1)
{
  uint32_t i = 0;
  const uint32_t n_logical_segments = grn_ii_n_logical_segments_inline(ii);
  for (;; i++) {
    if (i == n_logical_segments) {
      GRN_DEFINE_NAME(ii);
      MERR("[ii][buffer][segment][reserve] "
           "couldn't find a free buffer: <%.*s>: max:<%u>",
           name_size, name,
           n_logical_segments);
      return ctx->rc;
    }
    if (grn_ii_get_buffer_pseg_inline(ii, i) == GRN_II_PSEG_NOT_ASSIGNED) {
      break;
    }
  }
  *lseg0 = i++;
  for (;; i++) {
    if (i == n_logical_segments) {
      GRN_DEFINE_NAME(ii);
      MERR("[ii][buffer][segment][reserve] "
           "couldn't find two free buffers: "
           "<%.*s>: "
           "found:<%u>, max:<%u>",
           name_size, name,
           *lseg0, n_logical_segments);
      return ctx->rc;
    }
    if (grn_ii_get_buffer_pseg_inline(ii, i) == GRN_II_PSEG_NOT_ASSIGNED) {
      break;
    }
  }
  *lseg1 = i;
  if ((*pseg0 = segment_get(ctx, ii)) == ii->seg->header->max_segment) {
    GRN_DEFINE_NAME(ii);
    MERR("[ii][buffer][segment][reserve] "
         "couldn't allocate a free segment: <%.*s>: "
         "buffer:<%u>, max:<%u>",
         name_size, name,
         *lseg0, ii->seg->header->max_segment);
    return ctx->rc;
  }
  if ((*pseg1 = segment_get(ctx, ii)) == ii->seg->header->max_segment) {
    GRN_DEFINE_NAME(ii);
    MERR("[ii][buffer][segment][reserve] "
         "couldn't allocate two free segments: "
         "<%.*s>: "
         "found:<%u>, not-found:<%u>, max:<%u>",
         name_size, name,
         *lseg0, *lseg1, ii->seg->header->max_segment);
    return ctx->rc;
  }
  return ctx->rc;
}

grn_inline static void
buffer_garbage_enqueue(grn_ii *ii, uint32_t lseg)
{
  const uint32_t pseg = grn_ii_get_buffer_pseg_inline(ii, lseg);
  if (pseg != GRN_II_PSEG_NOT_ASSIGNED) {
    grn_ii_header_common *header = ii->header.common;
    header->bgqbody[header->bgqhead] = header->binfo[lseg];
    header->bgqhead = (header->bgqhead + 1) & (GRN_II_BGQSIZE - 1);
    GRN_ASSERT(header->bgqhead != header->bgqtail);
  }
}

grn_inline static void
buffer_segment_update(grn_ii *ii, uint32_t lseg, uint32_t pseg)
{
  buffer_garbage_enqueue(ii, lseg);
  // smb_wmb();
  grn_ii_set_buffer_pseg_inline(ii, lseg, pseg);
  if (lseg >= ii->header.common->bmax) {
    ii->header.common->bmax = lseg + 1;
  }
}

grn_inline static void
buffer_segment_clear(grn_ii *ii, uint32_t lseg)
{
  buffer_garbage_enqueue(ii, lseg);
  // smb_wmb();
  grn_ii_set_buffer_pseg_inline(ii, lseg, GRN_II_PSEG_NOT_ASSIGNED);
}

/* chunk */

#define HEADER_CHUNK_AT(ii,offset) \
  ((((ii)->header.common->chunks[((offset) >> 3)]) >> ((offset) & 7)) & 1)

#define HEADER_CHUNK_ON(ii,offset) \
  (((ii)->header.common->chunks[((offset) >> 3)]) |= (1 << ((offset) & 7)))

#define HEADER_CHUNK_OFF(ii,offset) \
  (((ii)->header.common->chunks[((offset) >> 3)]) &= ~(1 << ((offset) & 7)))

#define N_GARBAGES_TH 1

#define N_GARBAGES ((S_GARBAGE - (sizeof(uint32_t) * 4))/(sizeof(uint32_t)))

typedef struct {
  uint32_t head;
  uint32_t tail;
  uint32_t nrecs;
  uint32_t next;
  uint32_t recs[N_GARBAGES];
} grn_ii_ginfo;

#define WIN_MAP(ctx,chunk,iw,seg,pos,size,mode)\
  grn_io_win_map(ctx, chunk, iw,\
                 ((seg) >> GRN_II_N_CHUNK_VARIATION),\
                 (((seg) & ((1 << GRN_II_N_CHUNK_VARIATION) - 1)) << GRN_II_W_LEAST_CHUNK) + (pos),\
                 size, mode)

/*
static int new_histogram[32];
static int free_histogram[32];
*/

/*
  N = grn_ii_max_n_chunks_small  for GRN_OBJ_INDEX_SMALL
  N = GRN_II_MAX_N_CHUNKS_MEDIUM for GRN_OBJ_INDEX_MEDIUM
  N = GRN_II_MAX_N_CHUNKS        for GRN_OBJ_INDEX_LARGE
  N = GRN_II_MAX_N_CHUNKS        without index size flag

  S_CHUNK = (1 << GRN_II_W_CHUNK(22)) = 4MiB

  +------------+     +------------+
  |   chunk0   | ... |   chunkN   |
  +------------+     +------------+
  |<--S_CHUNK->|

  ii->header.common->chunks has flags whether the target chunk is
  assigned or not. We can manipulate the flags by HEADER_CHUNK_AT(),
  HEADER_CHUNK_ON() and HEADER_CHUNK_OFF(). Here is a snapshot when we
  only assign chunk0 and chunk2:

  +------------+------------+------------+     +------------+
  |   chunk0   |   chunk1   |   chunk2   | ... |   chunkN   |
  +------------+------------+------------+     +------------+
        ON          OFF           ON                 OFF

  If requested size is greater than S_CHUNK, continuous non-assigned
  chunks are assigned. For example, if S_CHUNK + 100 is requested and
  chunk1 is assigned, chunk0 isn't assigned. chunk2 and chunk3 are
  assigned.

  +------------+------------+------------+------------+     +------------+
  |   chunk0   |   chunk1   |   chunk2   |   chunk3   | ... |   chunkN   |
  +------------+------------+------------+------------+     +------------+
       OFF          ON        OFF -> ON    OFF -> ON             OFF

  If requested size is smaller than or equal to S_CHUNK, a subchunk is
  assigned. Subchunks in the same chunk has the same size. The
  smallest subchunk size is (1 << GRN_II_W_LEAST_CHUNK(8)) = 256
  bytes. Subchunk size is power of 2. For example, chunk0 uses 512
  bytes for subchunk size, chunk0 can have 812 (S_CHUNK / 512)
  subchunks.

  +-------------+
  |   chunk0    |
  +-------------+
  <->|<->|...|<-> subchunks
  512|512|   |512

  If one of subchunk is assigned, HEADER_CHUNK_AT() of the chunk is true.

  +-------------+
  |   chunk0    |
  +-------------+
  <------>|<->|... subchunks
  ASSIGNED|NOT|
        ON

  Chunks that are assigning subchunks are keeping in
  ii->header.common.free_chunks. free_chunks keeps a chunk per
  subchunk size. For example, chunk0 is kept for 256 subchunk size and
  chunk1 is kept for 512 subchunk size.

  chunk_new() returns the (offset >> GRN_II_W_LEAST_CHUNK(8)) of
  subchunk not the index of chunk. For example, if the third subchunk
  of chunk0 that uses 512 bytes for subchunk size is assigned, 4 (1024
  >> 8) is returned.

  +-------------+
  |   chunk0    |
  +-------------+
  <0>|<1>|<2>|...
  0   2   4

  chunk_new() wants to reuse freed subchunks as much as possible to
  reduce disk usage. ii->header.common.garbages keeps freed subchunks
  to reuse later.

  TODO: More description for garbages.
*/

static grn_rc
chunk_free(grn_ctx *ctx, grn_ii *ii, uint32_t offset, uint32_t size);

static grn_rc
chunk_new(grn_ctx *ctx, grn_ii *ii, uint32_t *res, uint32_t size)
{
  uint32_t n_chunks;

  n_chunks = ii->chunk->header->max_segment;

  /*
  if (size) {
    int m, es = size - 1;
    GRN_BIT_SCAN_REV(es, m);
    m++;
    new_histogram[m]++;
  }
  */
  if (size > S_CHUNK) {
    uint32_t i, j;
    uint32_t n = (size + S_CHUNK - 1) >> GRN_II_W_CHUNK;
    for (i = 0, j = -1; i < n_chunks; i++) {
      if (HEADER_CHUNK_AT(ii, i)) {
        j = i;
      } else {
        if (i == j + n) {
          j++;
          *res = j << GRN_II_N_CHUNK_VARIATION;
          for (; j <= i; j++) { HEADER_CHUNK_ON(ii, j); }
          return GRN_SUCCESS;
        }
      }
    }
    {
      GRN_DEFINE_NAME(ii);
      MERR("[ii][chunk][new] index is full: "
           "<%.*s>: "
           "size:<%u>, n-chunks:<%u>",
           name_size, name,
           size, n_chunks);
    }
    return ctx->rc;
  } else {
    uint32_t *vp;
    int m, aligned_size;
    if (size > (1 << GRN_II_W_LEAST_CHUNK)) {
      int es = size - 1;
      GRN_BIT_SCAN_REV(es, m);
      m++;
    } else {
      m = GRN_II_W_LEAST_CHUNK;
    }
    aligned_size = 1 << (m - GRN_II_W_LEAST_CHUNK);
    grn_ii_header_common *header = ii->header.common;
    if (header->ngarbages[m - GRN_II_W_LEAST_CHUNK] > N_GARBAGES_TH) {
      grn_ii_ginfo *ginfo;
      uint32_t *gseg;
      grn_io_win iw, iw_;
      iw_.addr = NULL;
      gseg = &header->garbages[m - GRN_II_W_LEAST_CHUNK];
      while (*gseg != GRN_II_PSEG_NOT_ASSIGNED) {
        ginfo = WIN_MAP(ctx, ii->chunk, &iw, *gseg, 0, S_GARBAGE, GRN_IO_RDWR);
        //GRN_IO_SEG_MAP2(ii->chunk, *gseg, ginfo);
        if (!ginfo) {
          if (iw_.addr) { grn_io_win_unmap(ctx, &iw_); }
          {
            GRN_DEFINE_NAME(ii);
            MERR("[ii][chunk][new] failed to allocate garbage segment: "
                 "<%.*s>: "
                 "n-garbages:<%u>, size:<%u>, n-chunks:<%u>",
                 name_size, name,
                 header->ngarbages[m - GRN_II_W_LEAST_CHUNK],
                 size,
                 n_chunks);
          }
          return ctx->rc;
        }
        if (ginfo->next != GRN_II_PSEG_NOT_ASSIGNED ||
            ginfo->nrecs > N_GARBAGES_TH) {
          *res = ginfo->recs[ginfo->tail];
          if (++ginfo->tail == N_GARBAGES) { ginfo->tail = 0; }
          ginfo->nrecs--;
          header->ngarbages[m - GRN_II_W_LEAST_CHUNK]--;
          uint32_t current_garbage_segment = *gseg;
          bool no_garbage_info = (ginfo->nrecs == 0);
          if (no_garbage_info) {
            *gseg = ginfo->next;
          }
          if (iw_.addr) { grn_io_win_unmap(ctx, &iw_); }
          grn_io_win_unmap(ctx, &iw);
          if (no_garbage_info) {
            chunk_free(ctx, ii, current_garbage_segment, S_GARBAGE);
          }
          return GRN_SUCCESS;
        }
        if (iw_.addr) { grn_io_win_unmap(ctx, &iw_); }
        iw_ = iw;
        gseg = &ginfo->next;
      }
      if (iw_.addr) { grn_io_win_unmap(ctx, &iw_); }
    }
    vp = &header->free_chunks[m - GRN_II_W_LEAST_CHUNK];
    if (*vp == GRN_II_PSEG_NOT_ASSIGNED) {
      uint32_t i = 0;
      while (HEADER_CHUNK_AT(ii, i)) {
        if (++i >= n_chunks) {
          GRN_DEFINE_NAME(ii);
          MERR("[ii][chunk][new] failed to find a free chunk: "
               "<%.*s>: "
               "index:<%u>, size:<%u>, n-chunks:<%u>",
               name_size, name,
               m - GRN_II_W_LEAST_CHUNK,
               size,
               n_chunks);
          return ctx->rc;
        }
      }
      HEADER_CHUNK_ON(ii, i);
      *vp = i << GRN_II_N_CHUNK_VARIATION;
    }
    *res = *vp;
    /* Next subchunk. */
    *vp += 1 << (m - GRN_II_W_LEAST_CHUNK);
    /* (*vp % GRN_II_N_CHUNK_VARIATION) == 0 */
    if (!(*vp & ((1 << GRN_II_N_CHUNK_VARIATION) - 1))) {
      /* All subchunks are consumed. */
      *vp = GRN_II_PSEG_NOT_ASSIGNED;
    }
    return GRN_SUCCESS;
  }
}

static grn_rc
chunk_free(grn_ctx *ctx, grn_ii *ii,
           uint32_t offset, uint32_t size)
{
  /*
  if (size) {
    int m, es = size - 1;
    GRN_BIT_SCAN_REV(es, m);
    m++;
    free_histogram[m]++;
  }
  */
  grn_io_win iw, iw_;
  grn_ii_ginfo *ginfo;
  uint32_t seg, m, *gseg;
  seg = offset >> GRN_II_N_CHUNK_VARIATION;
  if (size > S_CHUNK) {
    int n = (size + S_CHUNK - 1) >> GRN_II_W_CHUNK;
    for (; n--; seg++) { HEADER_CHUNK_OFF(ii, seg); }
    return GRN_SUCCESS;
  }
  if (size > (1 << GRN_II_W_LEAST_CHUNK)) {
    int es = size - 1;
    GRN_BIT_SCAN_REV(es, m);
    m++;
  } else {
    m = GRN_II_W_LEAST_CHUNK;
  }
  gseg = &ii->header.common->garbages[m - GRN_II_W_LEAST_CHUNK];
  iw_.addr = NULL;
  while (*gseg != GRN_II_PSEG_NOT_ASSIGNED) {
    ginfo = WIN_MAP(ctx, ii->chunk, &iw, *gseg, 0, S_GARBAGE, GRN_IO_RDWR);
    // GRN_IO_SEG_MAP2(ii->chunk, *gseg, ginfo);
    if (!ginfo) {
      if (iw_.addr) { grn_io_win_unmap(ctx, &iw_); }
      return GRN_NO_MEMORY_AVAILABLE;
    }
    if (ginfo->nrecs < N_GARBAGES) { break; }
    if (iw_.addr) { grn_io_win_unmap(ctx, &iw_); }
    iw_ = iw;
    gseg = &ginfo->next;
  }
  if (*gseg == GRN_II_PSEG_NOT_ASSIGNED) {
    grn_rc rc;
    if ((rc = chunk_new(ctx, ii, gseg, S_GARBAGE))) {
      if (iw_.addr) { grn_io_win_unmap(ctx, &iw_); }
      return rc;
    }
    ginfo = WIN_MAP(ctx, ii->chunk, &iw, *gseg, 0, S_GARBAGE, GRN_IO_RDWR);
    /*
    uint32_t i = 0;
    while (HEADER_CHUNK_AT(ii, i)) {
      if (++i >= ii->chunk->header->max_segment) {
        return GRN_NO_MEMORY_AVAILABLE;
      }
    }
    HEADER_CHUNK_ON(ii, i);
    *gseg = i;
    GRN_IO_SEG_MAP2(ii->chunk, *gseg, ginfo);
    */
    if (!ginfo) {
      if (iw_.addr) { grn_io_win_unmap(ctx, &iw_); }
      return GRN_NO_MEMORY_AVAILABLE;
    }
    ginfo->head = 0;
    ginfo->tail = 0;
    ginfo->nrecs = 0;
    ginfo->next = GRN_II_PSEG_NOT_ASSIGNED;
  }
  if (iw_.addr) { grn_io_win_unmap(ctx, &iw_); }
  ginfo->recs[ginfo->head] = offset;
  if (++ginfo->head == N_GARBAGES) { ginfo->head = 0; }
  ginfo->nrecs++;
  grn_io_win_unmap(ctx, &iw);
  ii->header.common->ngarbages[m - GRN_II_W_LEAST_CHUNK]++;
  return GRN_SUCCESS;
}

#define UNIT_SIZE 0x80
#define UNIT_MASK (UNIT_SIZE - 1)

/* <generated> */
static uint8_t *
pack_1(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  v = *p++ << 7;
  v += *p++ << 6;
  v += *p++ << 5;
  v += *p++ << 4;
  v += *p++ << 3;
  v += *p++ << 2;
  v += *p++ << 1;
  *rp++ = v + *p++;
  return rp;
}
static const uint8_t *
unpack_1(uint32_t *p, const uint8_t *dp)
{
  *p++ = (*dp >> 7);
  *p++ = ((*dp >> 6) & 0x1);
  *p++ = ((*dp >> 5) & 0x1);
  *p++ = ((*dp >> 4) & 0x1);
  *p++ = ((*dp >> 3) & 0x1);
  *p++ = ((*dp >> 2) & 0x1);
  *p++ = ((*dp >> 1) & 0x1);
  *p++ = (*dp++ & 0x1);
  return dp;
}
static uint8_t *
pack_2(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  v = *p++ << 6;
  v += *p++ << 4;
  v += *p++ << 2;
  *rp++ = v + *p++;
  v = *p++ << 6;
  v += *p++ << 4;
  v += *p++ << 2;
  *rp++ = v + *p++;
  return rp;
}
static const uint8_t *
unpack_2(uint32_t *p, const uint8_t *dp)
{
  *p++ = (*dp >> 6);
  *p++ = ((*dp >> 4) & 0x3);
  *p++ = ((*dp >> 2) & 0x3);
  *p++ = (*dp++ & 0x3);
  *p++ = (*dp >> 6);
  *p++ = ((*dp >> 4) & 0x3);
  *p++ = ((*dp >> 2) & 0x3);
  *p++ = (*dp++ & 0x3);
  return dp;
}
static uint8_t *
pack_3(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  v = *p++ << 5;
  v += *p++ << 2;
  *rp++ = v + (*p >> 1); v = *p++ << 7;
  v += *p++ << 4;
  v += *p++ << 1;
  *rp++ = v + (*p >> 2); v = *p++ << 6;
  v += *p++ << 3;
  *rp++ = v + *p++;
  return rp;
}
static const uint8_t *
unpack_3(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  *p++ = (*dp >> 5);
  *p++ = ((*dp >> 2) & 0x7);
  v = ((*dp++ << 1) & 0x7); *p++ = v + (*dp >> 7);
  *p++ = ((*dp >> 4) & 0x7);
  *p++ = ((*dp >> 1) & 0x7);
  v = ((*dp++ << 2) & 0x7); *p++ = v + (*dp >> 6);
  *p++ = ((*dp >> 3) & 0x7);
  *p++ = (*dp++ & 0x7);
  return dp;
}
static uint8_t *
pack_4(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  v = *p++ << 4;
  *rp++ = v + *p++;
  v = *p++ << 4;
  *rp++ = v + *p++;
  v = *p++ << 4;
  *rp++ = v + *p++;
  v = *p++ << 4;
  *rp++ = v + *p++;
  return rp;
}
static const uint8_t *
unpack_4(uint32_t *p, const uint8_t *dp)
{
  *p++ = (*dp >> 4);
  *p++ = (*dp++ & 0xf);
  *p++ = (*dp >> 4);
  *p++ = (*dp++ & 0xf);
  *p++ = (*dp >> 4);
  *p++ = (*dp++ & 0xf);
  *p++ = (*dp >> 4);
  *p++ = (*dp++ & 0xf);
  return dp;
}
static uint8_t *
pack_5(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  v = *p++ << 3;
  *rp++ = v + (*p >> 2); v = *p++ << 6;
  v += *p++ << 1;
  *rp++ = v + (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 1); v = *p++ << 7;
  v += *p++ << 2;
  *rp++ = v + (*p >> 3); v = *p++ << 5;
  *rp++ = v + *p++;
  return rp;
}
static const uint8_t *
unpack_5(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  *p++ = (*dp >> 3);
  v = ((*dp++ << 2) & 0x1f); *p++ = v + (*dp >> 6);
  *p++ = ((*dp >> 1) & 0x1f);
  v = ((*dp++ << 4) & 0x1f); *p++ = v + (*dp >> 4);
  v = ((*dp++ << 1) & 0x1f); *p++ = v + (*dp >> 7);
  *p++ = ((*dp >> 2) & 0x1f);
  v = ((*dp++ << 3) & 0x1f); *p++ = v + (*dp >> 5);
  *p++ = (*dp++ & 0x1f);
  return dp;
}
static uint8_t *
pack_6(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  v = *p++ << 2;
  *rp++ = v + (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 2); v = *p++ << 6;
  *rp++ = v + *p++;
  v = *p++ << 2;
  *rp++ = v + (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 2); v = *p++ << 6;
  *rp++ = v + *p++;
  return rp;
}
static const uint8_t *
unpack_6(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  *p++ = (*dp >> 2);
  v = ((*dp++ << 4) & 0x3f); *p++ = v + (*dp >> 4);
  v = ((*dp++ << 2) & 0x3f); *p++ = v + (*dp >> 6);
  *p++ = (*dp++ & 0x3f);
  *p++ = (*dp >> 2);
  v = ((*dp++ << 4) & 0x3f); *p++ = v + (*dp >> 4);
  v = ((*dp++ << 2) & 0x3f); *p++ = v + (*dp >> 6);
  *p++ = (*dp++ & 0x3f);
  return dp;
}
static uint8_t *
pack_7(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  v = *p++ << 1;
  *rp++ = v + (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 5); v = *p++ << 3;
  *rp++ = v + (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 3); v = *p++ << 5;
  *rp++ = v + (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 1); v = *p++ << 7;
  *rp++ = v + *p++;
  return rp;
}
static const uint8_t *
unpack_7(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  *p++ = (*dp >> 1);
  v = ((*dp++ << 6) & 0x7f); *p++ = v + (*dp >> 2);
  v = ((*dp++ << 5) & 0x7f); *p++ = v + (*dp >> 3);
  v = ((*dp++ << 4) & 0x7f); *p++ = v + (*dp >> 4);
  v = ((*dp++ << 3) & 0x7f); *p++ = v + (*dp >> 5);
  v = ((*dp++ << 2) & 0x7f); *p++ = v + (*dp >> 6);
  v = ((*dp++ << 1) & 0x7f); *p++ = v + (*dp >> 7);
  *p++ = (*dp++ & 0x7f);
  return dp;
}
static uint8_t *
pack_8(uint32_t *p, uint8_t *rp)
{
  *rp++ = *p++;
  *rp++ = *p++;
  *rp++ = *p++;
  *rp++ = *p++;
  *rp++ = *p++;
  *rp++ = *p++;
  *rp++ = *p++;
  *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_8(uint32_t *p, const uint8_t *dp)
{
  *p++ = *dp++;
  *p++ = *dp++;
  *p++ = *dp++;
  *p++ = *dp++;
  *p++ = *dp++;
  *p++ = *dp++;
  *p++ = *dp++;
  *p++ = *dp++;
  return dp;
}
static uint8_t *
pack_9(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 1); v = *p++ << 7;
  *rp++ = v + (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 3); v = *p++ << 5;
  *rp++ = v + (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 5); v = *p++ << 3;
  *rp++ = v + (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 7); v = *p++ << 1;
  *rp++ = v + (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_9(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 1; *p++ = v + (*dp >> 7);
  v = ((*dp++ << 2) & 0x1ff); *p++ = v + (*dp >> 6);
  v = ((*dp++ << 3) & 0x1ff); *p++ = v + (*dp >> 5);
  v = ((*dp++ << 4) & 0x1ff); *p++ = v + (*dp >> 4);
  v = ((*dp++ << 5) & 0x1ff); *p++ = v + (*dp >> 3);
  v = ((*dp++ << 6) & 0x1ff); *p++ = v + (*dp >> 2);
  v = ((*dp++ << 7) & 0x1ff); *p++ = v + (*dp >> 1);
  v = ((*dp++ << 8) & 0x1ff); *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_10(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_10(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 4) & 0x3ff); *p++ = v + (*dp >> 4);
  v = ((*dp++ << 6) & 0x3ff); *p++ = v + (*dp >> 2);
  v = ((*dp++ << 8) & 0x3ff); *p++ = v + *dp++;
  v = *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 4) & 0x3ff); *p++ = v + (*dp >> 4);
  v = ((*dp++ << 6) & 0x3ff); *p++ = v + (*dp >> 2);
  v = ((*dp++ << 8) & 0x3ff); *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_11(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 3); v = *p++ << 5;
  *rp++ = v + (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 9); *rp++ = (*p >> 1); v = *p++ << 7;
  *rp++ = v + (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 7); v = *p++ << 1;
  *rp++ = v + (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 5); v = *p++ << 3;
  *rp++ = v + (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_11(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 3; *p++ = v + (*dp >> 5);
  v = ((*dp++ << 6) & 0x7ff); *p++ = v + (*dp >> 2);
  v = ((*dp++ << 9) & 0x7ff); v += *dp++ << 1; *p++ = v + (*dp >> 7);
  v = ((*dp++ << 4) & 0x7ff); *p++ = v + (*dp >> 4);
  v = ((*dp++ << 7) & 0x7ff); *p++ = v + (*dp >> 1);
  v = ((*dp++ << 10) & 0x7ff); v += *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 5) & 0x7ff); *p++ = v + (*dp >> 3);
  v = ((*dp++ << 8) & 0x7ff); *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_12(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_12(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 8) & 0xfff); *p++ = v + *dp++;
  v = *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 8) & 0xfff); *p++ = v + *dp++;
  v = *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 8) & 0xfff); *p++ = v + *dp++;
  v = *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 8) & 0xfff); *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_13(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 5); v = *p++ << 3;
  *rp++ = v + (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 7); v = *p++ << 1;
  *rp++ = v + (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 9); *rp++ = (*p >> 1); v = *p++ << 7;
  *rp++ = v + (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 11); *rp++ = (*p >> 3); v = *p++ << 5;
  *rp++ = v + (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_13(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 5; *p++ = v + (*dp >> 3);
  v = ((*dp++ << 10) & 0x1fff); v += *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 7) & 0x1fff); *p++ = v + (*dp >> 1);
  v = ((*dp++ << 12) & 0x1fff); v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 9) & 0x1fff); v += *dp++ << 1; *p++ = v + (*dp >> 7);
  v = ((*dp++ << 6) & 0x1fff); *p++ = v + (*dp >> 2);
  v = ((*dp++ << 11) & 0x1fff); v += *dp++ << 3; *p++ = v + (*dp >> 5);
  v = ((*dp++ << 8) & 0x1fff); *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_14(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_14(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 6; *p++ = v + (*dp >> 2);
  v = ((*dp++ << 12) & 0x3fff); v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 10) & 0x3fff); v += *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 8) & 0x3fff); *p++ = v + *dp++;
  v = *dp++ << 6; *p++ = v + (*dp >> 2);
  v = ((*dp++ << 12) & 0x3fff); v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 10) & 0x3fff); v += *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 8) & 0x3fff); *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_15(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 7); v = *p++ << 1;
  *rp++ = v + (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 13); *rp++ = (*p >> 5); v = *p++ << 3;
  *rp++ = v + (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 11); *rp++ = (*p >> 3); v = *p++ << 5;
  *rp++ = v + (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 9); *rp++ = (*p >> 1); v = *p++ << 7;
  *rp++ = v + (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_15(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 7; *p++ = v + (*dp >> 1);
  v = ((*dp++ << 14) & 0x7fff); v += *dp++ << 6; *p++ = v + (*dp >> 2);
  v = ((*dp++ << 13) & 0x7fff); v += *dp++ << 5; *p++ = v + (*dp >> 3);
  v = ((*dp++ << 12) & 0x7fff); v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 11) & 0x7fff); v += *dp++ << 3; *p++ = v + (*dp >> 5);
  v = ((*dp++ << 10) & 0x7fff); v += *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 9) & 0x7fff); v += *dp++ << 1; *p++ = v + (*dp >> 7);
  v = ((*dp++ << 8) & 0x7fff); *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_16(uint32_t *p, uint8_t *rp)
{
  *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_16(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 8; *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_17(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 9); *rp++ = (*p >> 1); v = *p++ << 7;
  *rp++ = v + (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 11); *rp++ = (*p >> 3); v = *p++ << 5;
  *rp++ = v + (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 13); *rp++ = (*p >> 5); v = *p++ << 3;
  *rp++ = v + (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 15); *rp++ = (*p >> 7); v = *p++ << 1;
  *rp++ = v + (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_17(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 9; v += *dp++ << 1; *p++ = v + (*dp >> 7);
  v = ((*dp++ << 10) & 0x1ffff); v += *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 11) & 0x1ffff); v += *dp++ << 3; *p++ = v + (*dp >> 5);
  v = ((*dp++ << 12) & 0x1ffff); v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 13) & 0x1ffff); v += *dp++ << 5; *p++ = v + (*dp >> 3);
  v = ((*dp++ << 14) & 0x1ffff); v += *dp++ << 6; *p++ = v + (*dp >> 2);
  v = ((*dp++ << 15) & 0x1ffff); v += *dp++ << 7; *p++ = v + (*dp >> 1);
  v = ((*dp++ << 16) & 0x1ffff); v += *dp++ << 8; *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_18(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_18(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 10; v += *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 12) & 0x3ffff); v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 14) & 0x3ffff); v += *dp++ << 6; *p++ = v + (*dp >> 2);
  v = ((*dp++ << 16) & 0x3ffff); v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 10; v += *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 12) & 0x3ffff); v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 14) & 0x3ffff); v += *dp++ << 6; *p++ = v + (*dp >> 2);
  v = ((*dp++ << 16) & 0x3ffff); v += *dp++ << 8; *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_19(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 11); *rp++ = (*p >> 3); v = *p++ << 5;
  *rp++ = v + (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 17); *rp++ = (*p >> 9); *rp++ = (*p >> 1); v = *p++ << 7;
  *rp++ = v + (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 15); *rp++ = (*p >> 7); v = *p++ << 1;
  *rp++ = v + (*p >> 18); *rp++ = (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 13); *rp++ = (*p >> 5); v = *p++ << 3;
  *rp++ = v + (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_19(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 11; v += *dp++ << 3; *p++ = v + (*dp >> 5);
  v = ((*dp++ << 14) & 0x7ffff); v += *dp++ << 6; *p++ = v + (*dp >> 2);
  v = ((*dp++ << 17) & 0x7ffff); v += *dp++ << 9; v += *dp++ << 1;
  *p++ = v + (*dp >> 7);
  v = ((*dp++ << 12) & 0x7ffff); v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 15) & 0x7ffff); v += *dp++ << 7; *p++ = v + (*dp >> 1);
  v = ((*dp++ << 18) & 0x7ffff); v += *dp++ << 10; v += *dp++ << 2;
  *p++ = v + (*dp >> 6);
  v = ((*dp++ << 13) & 0x7ffff); v += *dp++ << 5; *p++ = v + (*dp >> 3);
  v = ((*dp++ << 16) & 0x7ffff); v += *dp++ << 8; *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_20(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_20(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 12; v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 16) & 0xfffff); v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 12; v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 16) & 0xfffff); v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 12; v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 16) & 0xfffff); v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 12; v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 16) & 0xfffff); v += *dp++ << 8; *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_21(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 13); *rp++ = (*p >> 5); v = *p++ << 3;
  *rp++ = v + (*p >> 18); *rp++ = (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 15); *rp++ = (*p >> 7); v = *p++ << 1;
  *rp++ = v + (*p >> 20); *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 17); *rp++ = (*p >> 9); *rp++ = (*p >> 1); v = *p++ << 7;
  *rp++ = v + (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 19); *rp++ = (*p >> 11); *rp++ = (*p >> 3); v = *p++ << 5;
  *rp++ = v + (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_21(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 13; v += *dp++ << 5; *p++ = v + (*dp >> 3);
  v = ((*dp++ << 18) & 0x1fffff); v += *dp++ << 10; v += *dp++ << 2;
  *p++ = v + (*dp >> 6);
  v = ((*dp++ << 15) & 0x1fffff); v += *dp++ << 7; *p++ = v + (*dp >> 1);
  v = ((*dp++ << 20) & 0x1fffff); v += *dp++ << 12; v += *dp++ << 4;
  *p++ = v + (*dp >> 4);
  v = ((*dp++ << 17) & 0x1fffff); v += *dp++ << 9; v += *dp++ << 1;
  *p++ = v + (*dp >> 7);
  v = ((*dp++ << 14) & 0x1fffff); v += *dp++ << 6; *p++ = v + (*dp >> 2);
  v = ((*dp++ << 19) & 0x1fffff); v += *dp++ << 11; v += *dp++ << 3;
  *p++ = v + (*dp >> 5);
  v = ((*dp++ << 16) & 0x1fffff); v += *dp++ << 8; *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_22(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 20); *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 18); *rp++ = (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 20); *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 18); *rp++ = (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_22(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 14; v += *dp++ << 6; *p++ = v + (*dp >> 2);
  v = ((*dp++ << 20) & 0x3fffff); v += *dp++ << 12; v += *dp++ << 4;
  *p++ = v + (*dp >> 4);
  v = ((*dp++ << 18) & 0x3fffff); v += *dp++ << 10; v += *dp++ << 2;
  *p++ = v + (*dp >> 6);
  v = ((*dp++ << 16) & 0x3fffff); v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 14; v += *dp++ << 6; *p++ = v + (*dp >> 2);
  v = ((*dp++ << 20) & 0x3fffff); v += *dp++ << 12; v += *dp++ << 4;
  *p++ = v + (*dp >> 4);
  v = ((*dp++ << 18) & 0x3fffff); v += *dp++ << 10; v += *dp++ << 2;
  *p++ = v + (*dp >> 6);
  v = ((*dp++ << 16) & 0x3fffff); v += *dp++ << 8; *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_23(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 15); *rp++ = (*p >> 7); v = *p++ << 1;
  *rp++ = v + (*p >> 22); *rp++ = (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 21); *rp++ = (*p >> 13); *rp++ = (*p >> 5); v = *p++ << 3;
  *rp++ = v + (*p >> 20); *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 19); *rp++ = (*p >> 11); *rp++ = (*p >> 3); v = *p++ << 5;
  *rp++ = v + (*p >> 18); *rp++ = (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 17); *rp++ = (*p >> 9); *rp++ = (*p >> 1); v = *p++ << 7;
  *rp++ = v + (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_23(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 15; v += *dp++ << 7; *p++ = v + (*dp >> 1);
  v = ((*dp++ << 22) & 0x7fffff); v += *dp++ << 14; v += *dp++ << 6;
  *p++ = v + (*dp >> 2);
  v = ((*dp++ << 21) & 0x7fffff); v += *dp++ << 13; v += *dp++ << 5;
  *p++ = v + (*dp >> 3);
  v = ((*dp++ << 20) & 0x7fffff); v += *dp++ << 12; v += *dp++ << 4;
  *p++ = v + (*dp >> 4);
  v = ((*dp++ << 19) & 0x7fffff); v += *dp++ << 11; v += *dp++ << 3;
  *p++ = v + (*dp >> 5);
  v = ((*dp++ << 18) & 0x7fffff); v += *dp++ << 10; v += *dp++ << 2;
  *p++ = v + (*dp >> 6);
  v = ((*dp++ << 17) & 0x7fffff); v += *dp++ << 9; v += *dp++ << 1;
  *p++ = v + (*dp >> 7);
  v = ((*dp++ << 16) & 0x7fffff); v += *dp++ << 8; *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_24(uint32_t *p, uint8_t *rp)
{
  *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_24(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_25(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 17); *rp++ = (*p >> 9); *rp++ = (*p >> 1); v = *p++ << 7;
  *rp++ = v + (*p >> 18); *rp++ = (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 19); *rp++ = (*p >> 11); *rp++ = (*p >> 3); v = *p++ << 5;
  *rp++ = v + (*p >> 20); *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 21); *rp++ = (*p >> 13); *rp++ = (*p >> 5); v = *p++ << 3;
  *rp++ = v + (*p >> 22); *rp++ = (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 23); *rp++ = (*p >> 15); *rp++ = (*p >> 7); v = *p++ << 1;
  *rp++ = v + (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_25(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 17; v += *dp++ << 9; v += *dp++ << 1; *p++ = v + (*dp >> 7);
  v = ((*dp++ << 18) & 0x1ffffff); v += *dp++ << 10; v += *dp++ << 2;
  *p++ = v + (*dp >> 6);
  v = ((*dp++ << 19) & 0x1ffffff); v += *dp++ << 11; v += *dp++ << 3;
  *p++ = v + (*dp >> 5);
  v = ((*dp++ << 20) & 0x1ffffff); v += *dp++ << 12; v += *dp++ << 4;
  *p++ = v + (*dp >> 4);
  v = ((*dp++ << 21) & 0x1ffffff); v += *dp++ << 13; v += *dp++ << 5;
  *p++ = v + (*dp >> 3);
  v = ((*dp++ << 22) & 0x1ffffff); v += *dp++ << 14; v += *dp++ << 6;
  *p++ = v + (*dp >> 2);
  v = ((*dp++ << 23) & 0x1ffffff); v += *dp++ << 15; v += *dp++ << 7;
  *p++ = v + (*dp >> 1);
  v = ((*dp++ << 24) & 0x1ffffff); v += *dp++ << 16; v += *dp++ << 8;
  *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_26(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 18); *rp++ = (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 20); *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 22); *rp++ = (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 18); *rp++ = (*p >> 10); *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 20); *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 22); *rp++ = (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_26(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 18; v += *dp++ << 10; v += *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 20) & 0x3ffffff); v += *dp++ << 12; v += *dp++ << 4;
  *p++ = v + (*dp >> 4);
  v = ((*dp++ << 22) & 0x3ffffff); v += *dp++ << 14; v += *dp++ << 6;
  *p++ = v + (*dp >> 2);
  v = ((*dp++ << 24) & 0x3ffffff); v += *dp++ << 16; v += *dp++ << 8;
  *p++ = v + *dp++;
  v = *dp++ << 18; v += *dp++ << 10; v += *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 20) & 0x3ffffff); v += *dp++ << 12; v += *dp++ << 4;
  *p++ = v + (*dp >> 4);
  v = ((*dp++ << 22) & 0x3ffffff); v += *dp++ << 14; v += *dp++ << 6;
  *p++ = v + (*dp >> 2);
  v = ((*dp++ << 24) & 0x3ffffff); v += *dp++ << 16; v += *dp++ << 8;
  *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_27(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 19); *rp++ = (*p >> 11); *rp++ = (*p >> 3); v = *p++ << 5;
  *rp++ = v + (*p >> 22); *rp++ = (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 25); *rp++ = (*p >> 17); *rp++ = (*p >> 9);
  *rp++ = (*p >> 1); v = *p++ << 7;
  *rp++ = v + (*p >> 20); *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 23); *rp++ = (*p >> 15); *rp++ = (*p >> 7); v = *p++ << 1;
  *rp++ = v + (*p >> 26); *rp++ = (*p >> 18); *rp++ = (*p >> 10);
  *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 21); *rp++ = (*p >> 13); *rp++ = (*p >> 5); v = *p++ << 3;
  *rp++ = v + (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_27(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 19; v += *dp++ << 11; v += *dp++ << 3; *p++ = v + (*dp >> 5);
  v = ((*dp++ << 22) & 0x7ffffff); v += *dp++ << 14; v += *dp++ << 6;
  *p++ = v + (*dp >> 2);
  v = ((*dp++ << 25) & 0x7ffffff); v += *dp++ << 17; v += *dp++ << 9;
  v += *dp++ << 1; *p++ = v + (*dp >> 7);
  v = ((*dp++ << 20) & 0x7ffffff); v += *dp++ << 12; v += *dp++ << 4;
  *p++ = v + (*dp >> 4);
  v = ((*dp++ << 23) & 0x7ffffff); v += *dp++ << 15; v += *dp++ << 7;
  *p++ = v + (*dp >> 1);
  v = ((*dp++ << 26) & 0x7ffffff); v += *dp++ << 18; v += *dp++ << 10;
  v += *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 21) & 0x7ffffff); v += *dp++ << 13; v += *dp++ << 5;
  *p++ = v + (*dp >> 3);
  v = ((*dp++ << 24) & 0x7ffffff); v += *dp++ << 16; v += *dp++ << 8;
  *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_28(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 20); *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 20); *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 20); *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 20); *rp++ = (*p >> 12); *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_28(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 20; v += *dp++ << 12; v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 24) & 0xfffffff); v += *dp++ << 16; v += *dp++ << 8;
  *p++ = v + *dp++;
  v = *dp++ << 20; v += *dp++ << 12; v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 24) & 0xfffffff); v += *dp++ << 16; v += *dp++ << 8;
  *p++ = v + *dp++;
  v = *dp++ << 20; v += *dp++ << 12; v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 24) & 0xfffffff); v += *dp++ << 16; v += *dp++ << 8;
  *p++ = v + *dp++;
  v = *dp++ << 20; v += *dp++ << 12; v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 24) & 0xfffffff); v += *dp++ << 16; v += *dp++ << 8;
  *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_29(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 21); *rp++ = (*p >> 13); *rp++ = (*p >> 5); v = *p++ << 3;
  *rp++ = v + (*p >> 26); *rp++ = (*p >> 18); *rp++ = (*p >> 10);
  *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 23); *rp++ = (*p >> 15); *rp++ = (*p >> 7); v = *p++ << 1;
  *rp++ = v + (*p >> 28); *rp++ = (*p >> 20); *rp++ = (*p >> 12);
  *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 25); *rp++ = (*p >> 17); *rp++ = (*p >> 9);
  *rp++ = (*p >> 1); v = *p++ << 7;
  *rp++ = v + (*p >> 22); *rp++ = (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 27); *rp++ = (*p >> 19); *rp++ = (*p >> 11);
  *rp++ = (*p >> 3); v = *p++ << 5;
  *rp++ = v + (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_29(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 21; v += *dp++ << 13; v += *dp++ << 5; *p++ = v + (*dp >> 3);
  v = ((*dp++ << 26) & 0x1fffffff); v += *dp++ << 18; v += *dp++ << 10;
  v += *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 23) & 0x1fffffff); v += *dp++ << 15; v += *dp++ << 7;
  *p++ = v + (*dp >> 1);
  v = ((*dp++ << 28) & 0x1fffffff); v += *dp++ << 20; v += *dp++ << 12;
  v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 25) & 0x1fffffff); v += *dp++ << 17; v += *dp++ << 9;
  v += *dp++ << 1; *p++ = v + (*dp >> 7);
  v = ((*dp++ << 22) & 0x1fffffff); v += *dp++ << 14; v += *dp++ << 6;
  *p++ = v + (*dp >> 2);
  v = ((*dp++ << 27) & 0x1fffffff); v += *dp++ << 19; v += *dp++ << 11;
  v += *dp++ << 3; *p++ = v + (*dp >> 5);
  v = ((*dp++ << 24) & 0x1fffffff); v += *dp++ << 16; v += *dp++ << 8;
  *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_30(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 22); *rp++ = (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 28); *rp++ = (*p >> 20); *rp++ = (*p >> 12);
  *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 26); *rp++ = (*p >> 18); *rp++ = (*p >> 10);
  *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 22); *rp++ = (*p >> 14); *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 28); *rp++ = (*p >> 20); *rp++ = (*p >> 12);
  *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 26); *rp++ = (*p >> 18); *rp++ = (*p >> 10);
  *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8);
  *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_30(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 22; v += *dp++ << 14; v += *dp++ << 6; *p++ = v + (*dp >> 2);
  v = ((*dp++ << 28) & 0x3fffffff); v += *dp++ << 20; v += *dp++ << 12;
  v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 26) & 0x3fffffff); v += *dp++ << 18; v += *dp++ << 10;
  v += *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 24) & 0x3fffffff); v += *dp++ << 16; v += *dp++ << 8;
  *p++ = v + *dp++;
  v = *dp++ << 22; v += *dp++ << 14; v += *dp++ << 6; *p++ = v + (*dp >> 2);
  v = ((*dp++ << 28) & 0x3fffffff); v += *dp++ << 20; v += *dp++ << 12;
  v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 26) & 0x3fffffff); v += *dp++ << 18; v += *dp++ << 10;
  v += *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 24) & 0x3fffffff); v += *dp++ << 16; v += *dp++ << 8;
  *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_31(uint32_t *p, uint8_t *rp)
{
  uint8_t v;
  *rp++ = (*p >> 23); *rp++ = (*p >> 15); *rp++ = (*p >> 7); v = *p++ << 1;
  *rp++ = v + (*p >> 30); *rp++ = (*p >> 22); *rp++ = (*p >> 14);
  *rp++ = (*p >> 6); v = *p++ << 2;
  *rp++ = v + (*p >> 29); *rp++ = (*p >> 21); *rp++ = (*p >> 13);
  *rp++ = (*p >> 5); v = *p++ << 3;
  *rp++ = v + (*p >> 28); *rp++ = (*p >> 20); *rp++ = (*p >> 12);
  *rp++ = (*p >> 4); v = *p++ << 4;
  *rp++ = v + (*p >> 27); *rp++ = (*p >> 19); *rp++ = (*p >> 11);
  *rp++ = (*p >> 3); v = *p++ << 5;
  *rp++ = v + (*p >> 26); *rp++ = (*p >> 18); *rp++ = (*p >> 10);
  *rp++ = (*p >> 2); v = *p++ << 6;
  *rp++ = v + (*p >> 25); *rp++ = (*p >> 17); *rp++ = (*p >> 9);
  *rp++ = (*p >> 1); v = *p++ << 7;
  *rp++ = v + (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8);
  *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_31(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 23; v += *dp++ << 15; v += *dp++ << 7; *p++ = v + (*dp >> 1);
  v = ((*dp++ << 30) & 0x7fffffff); v += *dp++ << 22; v += *dp++ << 14;
  v += *dp++ << 6; *p++ = v + (*dp >> 2);
  v = ((*dp++ << 29) & 0x7fffffff); v += *dp++ << 21; v += *dp++ << 13;
  v += *dp++ << 5; *p++ = v + (*dp >> 3);
  v = ((*dp++ << 28) & 0x7fffffff); v += *dp++ << 20; v += *dp++ << 12;
  v += *dp++ << 4; *p++ = v + (*dp >> 4);
  v = ((*dp++ << 27) & 0x7fffffff); v += *dp++ << 19; v += *dp++ << 11;
  v += *dp++ << 3; *p++ = v + (*dp >> 5);
  v = ((*dp++ << 26) & 0x7fffffff); v += *dp++ << 18; v += *dp++ << 10;
  v += *dp++ << 2; *p++ = v + (*dp >> 6);
  v = ((*dp++ << 25) & 0x7fffffff); v += *dp++ << 17; v += *dp++ << 9;
  v += *dp++ << 1; *p++ = v + (*dp >> 7);
  v = ((*dp++ << 24) & 0x7fffffff); v += *dp++ << 16; v += *dp++ << 8;
  *p++ = v + *dp++;
  return dp;
}
static uint8_t *
pack_32(uint32_t *p, uint8_t *rp)
{
  *rp++ = (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  *rp++ = (*p >> 24); *rp++ = (*p >> 16); *rp++ = (*p >> 8); *rp++ = *p++;
  return rp;
}
static const uint8_t *
unpack_32(uint32_t *p, const uint8_t *dp)
{
  uint32_t v;
  v = *dp++ << 24; v += *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 24; v += *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 24; v += *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 24; v += *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 24; v += *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 24; v += *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 24; v += *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  v = *dp++ << 24; v += *dp++ << 16; v += *dp++ << 8; *p++ = v + *dp++;
  return dp;
}
/* </generated> */

static uint8_t *
pack_(uint32_t *p, uint32_t i, int w, uint8_t *rp)
{
  while (i >= 8) {
    switch (w) {
    case  0 : break;
    case  1 : rp = pack_1(p, rp); break;
    case  2 : rp = pack_2(p, rp); break;
    case  3 : rp = pack_3(p, rp); break;
    case  4 : rp = pack_4(p, rp); break;
    case  5 : rp = pack_5(p, rp); break;
    case  6 : rp = pack_6(p, rp); break;
    case  7 : rp = pack_7(p, rp); break;
    case  8 : rp = pack_8(p, rp); break;
    case  9 : rp = pack_9(p, rp); break;
    case 10 : rp = pack_10(p, rp); break;
    case 11 : rp = pack_11(p, rp); break;
    case 12 : rp = pack_12(p, rp); break;
    case 13 : rp = pack_13(p, rp); break;
    case 14 : rp = pack_14(p, rp); break;
    case 15 : rp = pack_15(p, rp); break;
    case 16 : rp = pack_16(p, rp); break;
    case 17 : rp = pack_17(p, rp); break;
    case 18 : rp = pack_18(p, rp); break;
    case 19 : rp = pack_19(p, rp); break;
    case 20 : rp = pack_20(p, rp); break;
    case 21 : rp = pack_21(p, rp); break;
    case 22 : rp = pack_22(p, rp); break;
    case 23 : rp = pack_23(p, rp); break;
    case 24 : rp = pack_24(p, rp); break;
    case 25 : rp = pack_25(p, rp); break;
    case 26 : rp = pack_26(p, rp); break;
    case 27 : rp = pack_27(p, rp); break;
    case 28 : rp = pack_28(p, rp); break;
    case 29 : rp = pack_29(p, rp); break;
    case 30 : rp = pack_30(p, rp); break;
    case 31 : rp = pack_31(p, rp); break;
    case 32 : rp = pack_32(p, rp); break;
    }
    p += 8;
    i -= 8;
  }
  {
    int b;
    uint8_t v;
    uint32_t *pe = p + i;
    for (b = 8 - w, v = 0; p < pe;) {
      if (b > 0) {
        v += *p++ << b;
        b -= w;
      } else if (b < 0) {
        *rp++ = v + (*p >> -b);
        b += 8;
        v = 0;
      } else {
        *rp++ = v + *p++;
        b = 8 - w;
        v = 0;
      }
    }
    if (b + w != 8) { *rp++ = v; }
    return rp;
  }
}

/* TODO: This is too rough. I hope that this is large enough. */
#define PACK_MAX_SIZE ((UNIT_SIZE / 8) * 32 + (UNIT_SIZE * GRN_B_ENC_MAX_SIZE))

/*
 * PForDelta encode: M. Zukowski , S. Heman , N. Nes , P. Boncz,
 * Super-Scalar RAM-CPU Cache Compression, Proceedings of the 22nd
 * International Conference on Data Engineering, 2006
 *
 * w: b on the paper.
 * ebuf, ep: exception values on the paper.
 */
static uint8_t *
pack(uint32_t *p, uint32_t i, uint8_t *freq, uint8_t *rp)
{
  int32_t k, w;
  uint8_t ebuf[UNIT_SIZE], *ep = ebuf;
  uint32_t s, *pe = p + i, r, th = i - (i >> 3);
  for (w = 0, s = 0; w <= 32; w++) {
    if ((s += freq[w]) >= th) { break; }
  }
  if (i == s) {
    *rp++ = w;
    return pack_(p, i, w, rp);
  }
  r = 1 << w;
  *rp++ = w + 0x80;
  *rp++ = i - s;
  if (r >= UNIT_SIZE) {
    uint32_t first, *last = &first;
    for (k = 0; p < pe; p++, k++) {
      if (*p >= r) {
        GRN_B_ENC(*p - r, ep);
        *last = k;
        last = p;
      }
    }
    *last = 0;
    *rp++ = (uint8_t) first;
  } else {
    for (k = 0; p < pe; p++, k++) {
      if (*p >= r) {
        *ep++ = k;
        GRN_B_ENC(*p - r, ep);
        *p = 0;
      }
    }
  }
  rp = pack_(p - i, i, w, rp);
  grn_memcpy(rp, ebuf, ep - ebuf);
  return rp + (ep - ebuf);
}

#define USE_P_ENC (1<<0) /* Use PForDelta */
#define ODD       (1<<2) /* Variable size data */

typedef struct {
  uint32_t *data;
  uint32_t data_size;
  uint32_t flags;
} datavec;

static grn_rc
datavec_reset(grn_ctx *ctx, datavec *dv, uint32_t dvlen,
              size_t unitsize, size_t totalsize)
{
  uint32_t i;
  if (!dv[0].data || dv[dvlen].data < dv[0].data + totalsize) {
    if (dv[0].data) { GRN_FREE(dv[0].data); }
    if (!(dv[0].data = GRN_MALLOC(totalsize * sizeof(uint32_t)))) {
      MERR("[ii][data-vector][reset] failed to allocate data: "
           "length:<%u>, "
           "unit-size:<%" GRN_FMT_SIZE ">, "
           "total-size:<%" GRN_FMT_SIZE ">",
           dvlen,
           unitsize,
           totalsize);
      return ctx->rc;
    }
    dv[dvlen].data = dv[0].data + totalsize;
  }
  for (i = 1; i < dvlen; i++) {
    dv[i].data = dv[i - 1].data + unitsize;
  }
  return GRN_SUCCESS;
}

static grn_rc
datavec_init(grn_ctx *ctx, datavec *dv, uint32_t dvlen,
             size_t unitsize, size_t totalsize)
{
  uint32_t i;
  if (!totalsize) {
    memset(dv, 0, sizeof(datavec) * (dvlen + 1));
    return GRN_SUCCESS;
  }
  if (!(dv[0].data = GRN_MALLOC(totalsize * sizeof(uint32_t)))) {
    MERR("[ii][data-vector][init] failed to allocate data: "
         "length:<%u>, "
         "unit-size:<%" GRN_FMT_SIZE ">, "
         "total-size:<%" GRN_FMT_SIZE ">",
         dvlen,
         unitsize,
         totalsize);
    return ctx->rc;
  }
  dv[dvlen].data = dv[0].data + totalsize;
  for (i = 1; i < dvlen; i++) {
    dv[i].data = dv[i - 1].data + unitsize;
  }
  return GRN_SUCCESS;
}

static void
datavec_fin(grn_ctx *ctx, datavec *dv)
{
  if (dv[0].data) { GRN_FREE(dv[0].data); }
}

/* p is for PForDelta */
static ssize_t
grn_p_encv(grn_ctx *ctx, datavec *dv, uint32_t dvlen, uint8_t *res)
{
  uint8_t *rp = res;
  ssize_t estimated = 0;
  /* f in df is for frequency */
  uint32_t pgap, usep, l, df, data_size, *dp, *dpe;
  if (!dvlen || !(df = dv[0].data_size)) { return 0; }
  for (usep = 0, data_size = 0, l = 0; l < dvlen; l++) {
    uint32_t dl = dv[l].data_size;
    if (dl < df || ((dl > df) && (l != dvlen - 1))) {
      /* invalid argument */
      return -1;
    }
    usep += (dv[l].flags & USE_P_ENC) << l;
    data_size += dl;
  }
  pgap = data_size - df * dvlen;
  if (!usep) {
    if (rp) {
      GRN_B_ENC((df << 1) + 1, rp);
    } else {
      estimated += GRN_B_ENC_MAX_SIZE;
    }
    for (l = 0; l < dvlen; l++) {
      for (dp = dv[l].data, dpe = dp + dv[l].data_size; dp < dpe; dp++) {
        if (rp) {
          GRN_B_ENC(*dp, rp);
        } else {
          estimated += GRN_B_ENC_MAX_SIZE;
        }
      }
    }
  } else {
    if (rp) {
      GRN_B_ENC((usep << 1), rp);
      GRN_B_ENC(df, rp);
    } else {
      estimated += GRN_B_ENC_MAX_SIZE * 2;
    }
    if (dv[dvlen - 1].flags & ODD) {
      if (rp) {
        GRN_B_ENC(pgap, rp);
      } else {
        estimated += GRN_B_ENC_MAX_SIZE;
      }
    } else {
      GRN_ASSERT(!pgap);
    }
    for (l = 0; l < dvlen; l++) {
      dp = dv[l].data;
      dpe = dp + dv[l].data_size;
      if ((dv[l].flags & USE_P_ENC)) {
        uint32_t buf[UNIT_SIZE];
        uint8_t freq[33];
        uint32_t j = 0, d;
        memset(freq, 0, 33);
        while (dp < dpe) {
          if (j == UNIT_SIZE) {
            if (rp) {
              rp = pack(buf, j, freq, rp);
            } else {
              estimated += PACK_MAX_SIZE;
            }
            memset(freq, 0, 33);
            j = 0;
          }
          if ((d = buf[j++] = *dp++)) {
            uint32_t w;
            GRN_BIT_SCAN_REV(d, w);
            freq[w + 1]++;
          } else {
            freq[0]++;
          }
        }
        if (j > 0) {
          if (rp) {
            rp = pack(buf, j, freq, rp);
          } else {
            estimated += PACK_MAX_SIZE;
          }
        }
      } else {
        for (; dp < dpe; dp++) {
          if (rp) {
            GRN_B_ENC(*dp, rp);
          } else {
            estimated += GRN_B_ENC_MAX_SIZE;
          }
        }
      }
    }
  }
  if (rp) {
    return rp - res;
  } else {
    return estimated;
  }
}

#define GRN_B_DEC_CHECK(v,p,pe) do { \
  uint8_t *_p = (uint8_t *)p; \
  uint32_t _v; \
  if (_p >= pe) { return 0; } \
  _v = *_p++; \
  switch (_v >> 4) { \
  case 0x08 : \
    if (_v == 0x8f) { \
      if (_p + sizeof(uint32_t) > pe) { return 0; } \
      grn_memcpy(&_v, _p, sizeof(uint32_t)); \
      _p += sizeof(uint32_t); \
    } \
    break; \
  case 0x09 : \
    if (_p + 3 > pe) { return 0; } \
    _v = (_v - 0x90) * 0x100 + *_p++; \
    _v = _v * 0x100 + *_p++; \
    _v = _v * 0x100 + *_p++ + 0x20408f; \
    break; \
  case 0x0a : \
  case 0x0b : \
    if (_p + 2 > pe) { return 0; } \
    _v = (_v - 0xa0) * 0x100 + *_p++; \
    _v = _v * 0x100 + *_p++ + 0x408f; \
    break; \
  case 0x0c : \
  case 0x0d : \
  case 0x0e : \
  case 0x0f : \
    if (_p + 1 > pe) { return 0; } \
    _v = (_v - 0xc0) * 0x100 + *_p++ + 0x8f; \
    break; \
  } \
  v = _v; \
  p = _p; \
} while (0)

/*
 * PForDelta decode: M. Zukowski , S. Heman , N. Nes , P. Boncz,
 * Super-Scalar RAM-CPU Cache Compression, Proceedings of the 22nd
 * International Conference on Data Engineering, 2006
 *
 * w: b on the paper.
 * ne: the number of exception values on the paper.
 */
static const uint8_t *
unpack(const uint8_t *dp, const uint8_t *dpe, int i, uint32_t *rp)
{
  uint8_t ne = 0, k = 0, w = *dp++;
  uint32_t m, *p = rp;
  if (w & 0x80) {
    ne = *dp++;
    w -= 0x80;
    m = (1 << w) - 1;
    if (m >= UNIT_MASK) { k = *dp++; }
  } else {
    m = (1 << w) - 1;
  }
  if (w) {
    while (i >= 8) {
      if (dp + w > dpe) { return NULL; }
      switch (w) {
      case 1 : dp = unpack_1(p, dp); break;
      case 2 : dp = unpack_2(p, dp); break;
      case 3 : dp = unpack_3(p, dp); break;
      case 4 : dp = unpack_4(p, dp); break;
      case 5 : dp = unpack_5(p, dp); break;
      case 6 : dp = unpack_6(p, dp); break;
      case 7 : dp = unpack_7(p, dp); break;
      case 8 : dp = unpack_8(p, dp); break;
      case 9 : dp = unpack_9(p, dp); break;
      case 10 : dp = unpack_10(p, dp); break;
      case 11 : dp = unpack_11(p, dp); break;
      case 12 : dp = unpack_12(p, dp); break;
      case 13 : dp = unpack_13(p, dp); break;
      case 14 : dp = unpack_14(p, dp); break;
      case 15 : dp = unpack_15(p, dp); break;
      case 16 : dp = unpack_16(p, dp); break;
      case 17 : dp = unpack_17(p, dp); break;
      case 18 : dp = unpack_18(p, dp); break;
      case 19 : dp = unpack_19(p, dp); break;
      case 20 : dp = unpack_20(p, dp); break;
      case 21 : dp = unpack_21(p, dp); break;
      case 22 : dp = unpack_22(p, dp); break;
      case 23 : dp = unpack_23(p, dp); break;
      case 24 : dp = unpack_24(p, dp); break;
      case 25 : dp = unpack_25(p, dp); break;
      case 26 : dp = unpack_26(p, dp); break;
      case 27 : dp = unpack_27(p, dp); break;
      case 28 : dp = unpack_28(p, dp); break;
      case 29 : dp = unpack_29(p, dp); break;
      case 30 : dp = unpack_30(p, dp); break;
      case 31 : dp = unpack_31(p, dp); break;
      case 32 : dp = unpack_32(p, dp); break;
      }
      i -= 8;
      p += 8;
    }
    {
      int b;
      uint32_t v, *pe;
      for (b = 8 - w, v = 0, pe = p + i; p < pe && dp < dpe;) {
        if (b > 0) {
          *p++ = v + ((*dp >> b) & m);
          b -= w;
          v = 0;
        } else if (b < 0) {
          v += (*dp++ << -b) & m;
          b += 8;
        } else {
          *p++ = v + (*dp++ & m);
          b = 8 - w;
          v = 0;
        }
      }
      if (b + w != 8) { dp++; }
    }
  } else {
    memset(p, 0, sizeof(uint32_t) * i);
  }
  if (ne) {
    if (m >= UNIT_MASK) {
      uint32_t *pp;
      while (ne--) {
        pp = &rp[k];
        k = *pp;
        GRN_B_DEC_CHECK(*pp, dp, dpe);
        *pp += (m + 1);
      }
    } else {
      while (ne--) {
        k = *dp++;
        GRN_B_DEC_CHECK(rp[k], dp, dpe);
        rp[k] += (m + 1);
      }
    }
  }
  return dp;
}

static int
grn_p_decv(grn_ctx *ctx, grn_ii *ii, grn_id id,
           const uint8_t *data, uint32_t data_size, datavec *dv, uint32_t dvlen)
{
  size_t size;
  uint32_t df, l, i, *rp;
  const uint8_t *dp = data;
  const uint8_t *dpe = data + data_size;
  if (!data_size) {
    dv[0].data_size = 0;
    return 0;
  }
  if (!dvlen) { return 0; }
  GRN_B_DEC_CHECK(df, dp, dpe);
  if ((df & 1)) {
    df >>= 1;
    size = data_size;
    if (dv[dvlen].data < dv[0].data + size) {
      if (dv[0].data) {
        GRN_FREE(dv[0].data);
        dv[0].data = NULL;
      }
      if (!(rp = GRN_MALLOC(size * sizeof(uint32_t)))) {
        grn_obj term;
        GRN_DEFINE_NAME(ii);
        GRN_TEXT_INIT(&term, 0);
        if (id != GRN_ID_NIL) {
          grn_ii_get_term(ctx, ii, id, &term);
        }
        ERR(GRN_NO_MEMORY_AVAILABLE,
            "[ii][p-decv] failed to extend buffer for data vector: "
            "<%.*s>: "
            "<%.*s>(%u): "
            "%" GRN_FMT_SIZE " -> %" GRN_FMT_SIZE ": "
            "PForDelta(nothing)",
            name_size, name,
            (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
            id,
            dv[dvlen].data - dv[0].data,
            size);
        GRN_OBJ_FIN(ctx, &term);
        return 0;
      }
      dv[dvlen].data = rp + size;
    } else {
      rp = dv[0].data;
    }
    for (l = 0; l < dvlen; l++) {
      dv[l].data = rp;
      if (l < dvlen - 1) {
        for (i = 0; i < df; i++, rp++) { GRN_B_DEC_CHECK(*rp, dp, dpe); }
      } else {
        for (i = 0; dp < dpe; i++, rp++) { GRN_B_DEC_CHECK(*rp, dp, dpe); }
      }
      dv[l].data_size = i;
    }
  } else {
    uint32_t n, rest, usep = df >> 1;
    GRN_B_DEC_CHECK(df, dp, dpe);
    if (dv[dvlen -1].flags & ODD) {
      GRN_B_DEC_CHECK(rest, dp, dpe);
    } else {
      rest = 0;
    }
    size = df * dvlen + rest;
    if (dv[dvlen].data < dv[0].data + size) {
      if (dv[0].data) {
        GRN_FREE(dv[0].data);
        dv[0].data = NULL;
      }
      if (!(rp = GRN_MALLOC(size * sizeof(uint32_t)))) {
        grn_obj term;
        GRN_DEFINE_NAME(ii);
        GRN_TEXT_INIT(&term, 0);
        if (id != GRN_ID_NIL) {
          grn_ii_get_term(ctx, ii, id, &term);
        }
        ERR(GRN_NO_MEMORY_AVAILABLE,
            "[ii][p-decv] failed to extend buffer for data vector: "
            "<%.*s>: "
            "<%.*s>(%u): "
            "%" GRN_FMT_SIZE " -> %" GRN_FMT_SIZE ": "
            "PForDelta(%s)",
            name_size, name,
            (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
            id,
            dv[dvlen].data - dv[0].data,
            size,
            usep ? "true" : "false");
        GRN_OBJ_FIN(ctx, &term);
        return 0;
      }
      dv[dvlen].data = rp + size;
    } else {
      rp = dv[0].data;
    }
    for (l = 0; l < dvlen; l++) {
      dv[l].data = rp;
      dv[l].data_size = n = (l < dvlen - 1) ? df : df + rest;
      if (usep & (USE_P_ENC << l)) {
        for (; n >= UNIT_SIZE; n -= UNIT_SIZE) {
          const uint8_t *next_dp = unpack(dp, dpe, UNIT_SIZE, rp);
          if (!next_dp) {
            grn_obj term;
            GRN_DEFINE_NAME(ii);
            GRN_TEXT_INIT(&term, 0);
            if (id != GRN_ID_NIL) {
              grn_ii_get_term(ctx, ii, id, &term);
            }
            ERR(GRN_FILE_CORRUPT,
                "[ii][p-decv] "
                "failed to unpack PForDelta encoded fixed size data: "
                "<%.*s>: "
                "<%.*s>(%u): "
                "df(%u): "
                "rest(%u): "
                "dv[%u/%u](%u/%u): "
                "data(%u/%u)",
                name_size, name,
                (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                id,
                df,
                rest,
                l,
                dvlen,
                dv[l].data_size - n,
                dv[l].data_size,
                (uint32_t)(dp - data),
                data_size);
            GRN_OBJ_FIN(ctx, &term);
            return 0;
          }
          dp = next_dp;
          rp += UNIT_SIZE;
        }
        if (n) {
          const uint8_t *next_dp = unpack(dp, dpe, n, rp);
          if (!next_dp) {
            grn_obj term;
            GRN_DEFINE_NAME(ii);
            GRN_TEXT_INIT(&term, 0);
            if (id != GRN_ID_NIL) {
              grn_ii_get_term(ctx, ii, id, &term);
            }
            ERR(GRN_FILE_CORRUPT,
                "[ii][p-decv] failed to unpack PForDelta encoded rest data: "
                "<%.*s>: "
                "<%.*s>(%u): "
                "df(%u): "
                "rest(%u): "
                "dv[%u/%u](%u/%u): "
                "data(%u/%u)",
                name_size, name,
                (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                id,
                df,
                rest,
                l,
                dvlen,
                dv[l].data_size - n,
                dv[l].data_size,
                (uint32_t)(dp - data),
                data_size);
            GRN_OBJ_FIN(ctx, &term);
            return 0;
          }
          dp = next_dp;
          rp += n;
        }
        dv[l].flags |= USE_P_ENC;
      } else {
        for (; n; n--, rp++) {
          GRN_B_DEC_CHECK(*rp, dp, dpe);
        }
      }
    }
    GRN_ASSERT(dp == dpe);
    if (dp != dpe) {
      grn_obj term;
      GRN_DEFINE_NAME(ii);
      GRN_TEXT_INIT(&term, 0);
      grn_ii_get_term(ctx, ii, id, &term);
      if (df == 0) {
        GRN_LOG(ctx, GRN_LOG_WARNING,
                "[ii][p-decv][%.*s][%*.s][%u] "
                "encoded data frequency is unexpected: <0>: data(%u/%u)",
                name_size, name,
                (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                id,
                (uint32_t)(dp - data),
                data_size);
      } else {
        GRN_LOG(ctx, GRN_LOG_DEBUG,
                "[ii][p-decv][%.*s][%*.s][%u] "
                "failed to decode: <%u>: data(%u/%u)",
                name_size, name,
                (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                id,
                df,
                (uint32_t)(dp - data),
                data_size);
      }
      GRN_OBJ_FIN(ctx, &term);
    }
  }
  return rp - dv[0].data;
}

int
grn_b_enc(grn_ctx *ctx, uint32_t *data, uint32_t data_size, uint8_t **res)
{
  uint8_t *rp;
  uint32_t *dp, i;
  *res = rp = GRN_MALLOC(data_size * sizeof(uint32_t) * 2);
  GRN_B_ENC(data_size, rp);
  for (i = data_size, dp = data; i; i--, dp++) {
    GRN_B_ENC(*dp, rp);
  }
  return rp - *res;
}

int
grn_b_dec(grn_ctx *ctx, uint8_t *data, uint32_t data_size, uint32_t **res)
{
  uint32_t i, *rp, orig_size;
  uint8_t *dp = data;
  GRN_B_DEC(orig_size, dp);
  *res = rp = GRN_MALLOC(orig_size * sizeof(uint32_t));
  for (i = orig_size; i; i--, rp++) {
    GRN_B_DEC(*rp, dp);
  }
  return orig_size;
}

/* buffer */

typedef struct {
  uint32_t tid;
  uint32_t size_in_chunk;
  uint32_t pos_in_chunk;
  uint16_t size_in_buffer;
  uint16_t pos_in_buffer;
} buffer_term;

typedef struct {
  uint16_t step;
  uint16_t jump;
} buffer_rec;

typedef struct {
  uint32_t chunk;
  uint32_t chunk_size;
  uint32_t buffer_free;
  uint16_t nterms;
  uint16_t nterms_void;
} buffer_header;

typedef struct {
  buffer_header header;
  buffer_term terms[(S_SEGMENT - sizeof(buffer_header))/sizeof(buffer_term)];
} buffer;

#define GRN_II_POS_LSEG_SHIFT_SIZE (32 - GRN_II_W_LSEG)
#define GRN_II_POS_LSEG_SHIFT_SIZE_LARGE (32 - GRN_II_W_LSEG_LARGE)
#define GRN_II_POS_LOFFSET_SHIFT_SIZE           \
  ((16 - GRN_II_W_LOFFSET) + 2)
#define GRN_II_POS_LOFFSET_SHIFT_SIZE_LARGE     \
  ((16 - GRN_II_W_LOFFSET_LARGE) + 2)

grn_inline static uint32_t
grn_ii_pos_lseg(grn_ii *ii, uint32_t pos)
{
  if (ii->header.common->flags & GRN_OBJ_INDEX_LARGE) {
    return pos >> GRN_II_POS_LSEG_SHIFT_SIZE_LARGE;
  } else {
    return pos >> GRN_II_POS_LSEG_SHIFT_SIZE;
  }
}

grn_inline static uint32_t
grn_ii_pos_loffset(grn_ii *ii, uint32_t pos)
{
  if (ii->header.common->flags & GRN_OBJ_INDEX_LARGE) {
    return
      (pos & ((1 << GRN_II_W_LOFFSET_LARGE) - 1)) <<
      GRN_II_POS_LOFFSET_SHIFT_SIZE_LARGE;
  } else {
    return
      (pos & ((1 << GRN_II_W_LOFFSET) - 1)) <<
      GRN_II_POS_LOFFSET_SHIFT_SIZE;
  }
}

grn_inline static uint32_t
grn_ii_pos_pack(grn_ii *ii, uint32_t lseg, uint32_t loffset)
{
  if (ii->header.common->flags & GRN_OBJ_INDEX_LARGE) {
    return
      (lseg << GRN_II_POS_LSEG_SHIFT_SIZE_LARGE) +
      (loffset >> GRN_II_POS_LOFFSET_SHIFT_SIZE_LARGE);
  } else {
    return
      (lseg << GRN_II_POS_LSEG_SHIFT_SIZE) +
      (loffset >> GRN_II_POS_LOFFSET_SHIFT_SIZE);
  }
}

#define POS_LOFFSET_HEADER sizeof(buffer_header)
#define POS_LOFFSET_TERM sizeof(buffer_term)

grn_inline static bool
grn_ii_pos_is_available(grn_ctx *ctx,
                        uint32_t flags,
                        const char *context)
{
  if (flags & GRN_OBJ_INDEX_LARGE) {
    if ((POS_LOFFSET_HEADER % 4) != 0) {
      ERR(GRN_OPERATION_NOT_SUPPORTED,
          "%s INDEX_LARGE requires 32bit aligned offset header: "
          "<%" GRN_FMT_SIZE ">",
          context,
          POS_LOFFSET_HEADER);
      return false;
    }
    if ((POS_LOFFSET_TERM % 4) != 0) {
      ERR(GRN_OPERATION_NOT_SUPPORTED,
          "%s INDEX_LARGE requires 32bit aligned offset term: "
          "<%" GRN_FMT_SIZE ">",
          context,
          POS_LOFFSET_TERM);
      return false;
    }
  }
  return true;
}

#define POS_IS_EMBED(pos) ((pos) & 1)
#define POS_EMBED_RID(rid) (((rid) << 1) | 1)
#define POS_EMBED_RID_SID(rid, sid) ((((rid) << 12) + ((sid) << 1)) | 1)
#define POS_RID_EXTRACT(pos) ((pos) >> 1)
#define POS_RID_SID_EXTRACT_RID(pos) BIT31_12((pos))
#define POS_RID_SID_EXTRACT_SID(pos) BIT11_01((pos))

grn_inline static uint32_t
buffer_open(grn_ctx *ctx, grn_ii *ii, uint32_t pos, buffer_term **bt, buffer **b)
{
  const uint32_t lseg = grn_ii_pos_lseg(ii, pos);
  const uint32_t pseg = grn_ii_get_buffer_pseg_inline(ii, lseg);
  if (pseg != GRN_II_PSEG_NOT_ASSIGNED) {
    byte *p = grn_io_seg_ref(ctx, ii->seg, pseg);
    if (!p) { return GRN_II_PSEG_NOT_ASSIGNED; }
    if (b) { *b = (buffer *)p; }
    if (bt) { *bt = (buffer_term *)(p + grn_ii_pos_loffset(ii, pos)); }
  }
  return pseg;
}

grn_inline static grn_rc
buffer_close(grn_ctx *ctx, grn_ii *ii, uint32_t pseg)
{
  if (pseg >= ii->seg->header->max_segment) {
    GRN_LOG(ctx, GRN_LOG_NOTICE, "invalid pseg buffer_close(%d)", pseg);
    return GRN_INVALID_ARGUMENT;
  }
  grn_io_seg_unref(ctx, ii->seg, pseg);
  return GRN_SUCCESS;
}

typedef struct {
  uint32_t rid;
  uint32_t sid;
} docid;

#define BUFFER_REC_DEL(r)     ((r)->jump = 1)
#define BUFFER_REC_DELETED(r) ((r)->jump == 1)

#define BUFFER_REC_AT(b,pos)  ((buffer_rec *)(b) + (pos))
#define BUFFER_REC_POS(b,rec) ((uint16_t)((rec) - (buffer_rec *)(b)))

grn_inline static void
buffer_term_dump(grn_ctx *ctx, grn_ii *ii, buffer *b, buffer_term *bt)
{
  int pos, rid, sid;
  uint8_t *p;
  buffer_rec *r;

  if (!grn_logger_pass(ctx, GRN_LOG_DEBUG)) {
    return;
  }

  GRN_LOG(ctx, GRN_LOG_DEBUG,
          "b=(%x %u %u %u)", b->header.chunk, b->header.chunk_size,
          b->header.buffer_free, b->header.nterms);
  GRN_LOG(ctx, GRN_LOG_DEBUG,
          "bt=(%u %u %u %u %u)", bt->tid, bt->size_in_chunk, bt->pos_in_chunk,
          bt->size_in_buffer, bt->pos_in_buffer);
  for (pos = bt->pos_in_buffer; pos; pos = r->step) {
    r = BUFFER_REC_AT(b, pos);
    p = GRN_NEXT_ADDR(r);
    GRN_B_DEC(rid, p);
    if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
      GRN_B_DEC(sid, p);
    } else {
      sid = 1;
    }
    GRN_LOG(ctx, GRN_LOG_DEBUG,
            "%d=(%d:%d),(%d:%d)", pos, r->jump, r->step, rid, sid);
  }
}

grn_inline static grn_rc
check_jump(grn_ctx *ctx, grn_ii *ii, buffer *b, buffer_rec *r, int j)
{
  uint16_t i = BUFFER_REC_POS(b, r);
  uint8_t *p;
  buffer_rec *r2;
  docid id, id2;
  if (!j) { return GRN_SUCCESS; }
  p = GRN_NEXT_ADDR(r);
  GRN_B_DEC(id.rid, p);
  if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
    GRN_B_DEC(id.sid, p);
  } else {
    id.sid = 1;
  }
  if (j == 1) {
    GRN_LOG(ctx, GRN_LOG_DEBUG, "deleting! %d(%d:%d)", i, id.rid, id.sid);
    return GRN_SUCCESS;
  }
  r2 = BUFFER_REC_AT(b, j);
  p = GRN_NEXT_ADDR(r2);
  GRN_B_DEC(id2.rid, p);
  if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
    GRN_B_DEC(id2.sid, p);
  } else {
    id2.sid = 1;
  }
  if (r2->step == i) {
    GRN_LOG(ctx, GRN_LOG_EMERG, "cycle! %d(%d:%d)<->%d(%d:%d)",
            i, id.rid, id.sid, j, id2.rid, id2.sid);
    return GRN_FILE_CORRUPT;
  }
  if (id2.rid < id.rid || (id2.rid == id.rid && id2.sid <= id.sid)) {
    GRN_LOG(ctx, GRN_LOG_CRIT,
            "invalid jump! %d(%d:%d)(%d:%d)->%d(%d:%d)(%d:%d)",
            i, r->jump, r->step, id.rid, id.sid, j, r2->jump, r2->step,
            id2.rid, id2.sid);
    return GRN_FILE_CORRUPT;
  }
  return GRN_SUCCESS;
}

grn_inline static grn_rc
set_jump_r(grn_ctx *ctx, grn_ii *ii, buffer *b, buffer_rec *from, int to)
{
  int i, j, max_jump = 100;
  buffer_rec *r, *r2;
  for (r = from, j = to; j > 1 && max_jump--; r = BUFFER_REC_AT(b, r->step)) {
    r2 = BUFFER_REC_AT(b, j);
    if (r == r2) { break; }
    if (BUFFER_REC_DELETED(r2)) { break; }
    if (j == (i = r->jump)) { break; }
    if (j == r->step) { break; }
    if (check_jump(ctx, ii, b, r, j)) {
      ERR(GRN_FILE_CORRUPT, "check_jump failed");
      return ctx->rc;
    }
    r->jump = j;
    j = i;
    if (!r->step) { return GRN_FILE_CORRUPT; }
  }
  return GRN_SUCCESS;
}

#define GET_NUM_BITS(x,n) do {\
  n = x;\
  n = (n & 0x55555555) + ((n >> 1) & 0x55555555);\
  n = (n & 0x33333333) + ((n >> 2) & 0x33333333);\
  n = (n & 0x0F0F0F0F) + ((n >> 4) & 0x0F0F0F0F);\
  n = (n & 0x00FF00FF) + ((n >> 8) & 0x00FF00FF);\
  n = (n & 0x0000FFFF) + ((n >>16) & 0x0000FFFF);\
} while (0)

grn_inline static grn_rc
buffer_put(grn_ctx *ctx, grn_ii *ii, buffer *b, buffer_term *bt,
           buffer_rec *rnew, uint8_t *bs, grn_ii_updspec *u, int size)
{
  uint8_t *p;
  docid id_curr = {0, 0}, id_start = {0, 0}, id_post = {0, 0};
  buffer_rec *r_curr, *r_start = NULL;
  uint16_t last = 0, *lastp = &bt->pos_in_buffer, pos = BUFFER_REC_POS(b, rnew);
  int vdelta = 0, delta, delta0 = 0, vhops = 0, nhops = 0, reset = 1;
  grn_memcpy(GRN_NEXT_ADDR(rnew), bs, size - sizeof(buffer_rec));
  for (;;) {
    if (!*lastp) {
      rnew->step = 0;
      rnew->jump = 0;
      // smb_wmb();
      *lastp = pos;
      if (bt->size_in_buffer++ > 1) {
        buffer_rec *rhead = BUFFER_REC_AT(b, bt->pos_in_buffer);
        rhead->jump = pos;
        if (!(bt->size_in_buffer & 1)) {
          int n;
          buffer_rec *r = BUFFER_REC_AT(b, rhead->step), *r2;
          GET_NUM_BITS(bt->size_in_buffer, n);
          while (n-- && (r->jump > 1)) {
            r2 = BUFFER_REC_AT(b, r->jump);
            if (BUFFER_REC_DELETED(r2)) { break; }
            r = r2;
          }
          if (r != rnew) { set_jump_r(ctx, ii, b, r, last); }
        }
      }
      break;
    }
    r_curr = BUFFER_REC_AT(b, *lastp);
    p = GRN_NEXT_ADDR(r_curr);
    GRN_B_DEC(id_curr.rid, p);
    if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
      GRN_B_DEC(id_curr.sid, p);
    } else {
      id_curr.sid = 1;
    }
    if (id_curr.rid < id_post.rid ||
        (id_curr.rid == id_post.rid && id_curr.sid < id_post.sid)) {
      {
        GRN_DEFINE_NAME(ii);
        CRIT(GRN_FILE_CORRUPT,
             "[ii][buffer][put] loop is found: "
             "<%.*s>: "
             "(%d:%d)->(%d:%d)",
             name_size, name,
             id_post.rid, id_post.sid, id_curr.rid, id_curr.sid);
      }
      buffer_term_dump(ctx, ii, b, bt);
      bt->pos_in_buffer = 0;
      bt->size_in_buffer = 0;
      lastp = &bt->pos_in_buffer;
      continue;
    }
    id_post.rid = id_curr.rid;
    id_post.sid = id_curr.sid;
    if (u->rid < id_curr.rid || (u->rid == id_curr.rid && u->sid <= id_curr.sid)) {
      uint16_t step = *lastp, jump = r_curr->jump;
      if (u->rid == id_curr.rid) {
        if (u->sid == 0) {
          while (id_curr.rid == u->rid) {
            BUFFER_REC_DEL(r_curr);
            if (!(step = r_curr->step)) { break; }
            r_curr = BUFFER_REC_AT(b, step);
            p = GRN_NEXT_ADDR(r_curr);
            GRN_B_DEC(id_curr.rid, p);
            if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
              GRN_B_DEC(id_curr.sid, p);
            } else {
              id_curr.sid = 1;
            }
          }
        } else if (u->sid == id_curr.sid) {
          BUFFER_REC_DEL(r_curr);
          step = r_curr->step;
        }
      }
      rnew->step = step;
      rnew->jump = check_jump(ctx, ii, b, rnew, jump) ? 0 : jump;
      // smb_wmb();
      *lastp = pos;
      break;
    }

    if (reset) {
      r_start = r_curr;
      id_start.rid = id_curr.rid;
      id_start.sid = id_curr.sid;
      if (!(delta0 = u->rid - id_start.rid)) { delta0 = u->sid - id_start.sid; }
      nhops = 0;
      vhops = 1;
      vdelta = delta0 >> 1;
    } else {
      if (!(delta = id_curr.rid - id_start.rid)) {
        delta = id_curr.sid - id_start.sid;
      }
      if (vdelta < delta) {
        vdelta += (delta0 >> ++vhops);
        r_start = r_curr;
      }
      if (nhops > vhops) {
        set_jump_r(ctx, ii, b, r_start, *lastp);
      } else {
        nhops++;
      }
    }

    last = *lastp;
    lastp = &r_curr->step;
    reset = 0;
    {
      uint16_t posj = r_curr->jump;
      if (posj > 1) {
        buffer_rec *rj = BUFFER_REC_AT(b, posj);
        if (!BUFFER_REC_DELETED(rj)) {
          docid idj;
          p = GRN_NEXT_ADDR(rj);
          GRN_B_DEC(idj.rid, p);
          if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
            GRN_B_DEC(idj.sid, p);
          } else {
            idj.sid = 1;
          }
          if (idj.rid < u->rid || (idj.rid == u->rid && idj.sid < u->sid)) {
            last = posj;
            lastp = &rj->step;
          } else {
            reset = 1;
          }
        }
      }
    }
  }
  return ctx->rc;
}

/* array */

grn_inline static uint32_t *
array_at(grn_ctx *ctx, grn_ii *ii, uint32_t id)
{
  if (id > GRN_ID_MAX) { return NULL; }
  const uint16_t seg = id >> W_ARRAY;
  const uint32_t pseg = grn_ii_get_array_pseg_inline(ii, seg);
  if (pseg == GRN_II_PSEG_NOT_ASSIGNED) {
    return NULL;
  }
  byte *p = grn_io_seg_ref(ctx, ii->seg, pseg);
  if (!p) { return NULL; }
  return (uint32_t *)(p + (id & ARRAY_MASK_IN_A_SEGMENT) * S_ARRAY_ELEMENT);
}

grn_inline static uint32_t *
array_get(grn_ctx *ctx, grn_ii *ii, uint32_t id)
{
  byte *p = NULL;
  if (id > GRN_ID_MAX) { return NULL; }
  const uint16_t seg = id >> W_ARRAY;
  uint32_t pseg = grn_ii_get_array_pseg_inline(ii, seg);
  if (pseg == GRN_II_PSEG_NOT_ASSIGNED) {
    if (segment_get_clear(ctx, ii, &pseg)) { return NULL; }
    grn_ii_set_array_pseg_inline(ii, seg, pseg);
    if (seg >= ii->header.common->amax) {
      ii->header.common->amax = seg + 1;
    }
  }
  p = grn_io_seg_ref(ctx, ii->seg, pseg);
  if (!p) { return NULL; }
  return (uint32_t *)(p + (id & ARRAY_MASK_IN_A_SEGMENT) * S_ARRAY_ELEMENT);
}

grn_inline static void
array_unref(grn_ctx *ctx, grn_ii *ii, uint32_t id)
{
  const uint32_t pseg = grn_ii_get_array_pseg_inline(ii, id >> W_ARRAY);
  grn_io_seg_unref(ctx, ii->seg, pseg);
}

/* updspec */

grn_ii_updspec *
grn_ii_updspec_open(grn_ctx *ctx, uint32_t rid, uint32_t sid)
{
  grn_ii_updspec *u;
  if (!(u = GRN_CALLOC(sizeof(grn_ii_updspec)))) { return NULL; }
  u->rid = rid;
  u->sid = sid;
  u->weight = 0;
  u->tf = 0;
  u->atf = 0;
  u->pos = NULL;
  u->tail = NULL;
  //  u->vnodes = NULL;
  return u;
}

#define GRN_II_MAX_TF 0x1ffff

grn_rc
grn_ii_updspec_add(grn_ctx *ctx, grn_ii_updspec *u, int pos, int32_t weight)
{
  struct _grn_ii_pos *p;
  u->atf++;
  if (u->tf >= GRN_II_MAX_TF) { return GRN_SUCCESS; }
  if (!(p = GRN_CALLOC(sizeof(struct _grn_ii_pos)))) {
    return GRN_NO_MEMORY_AVAILABLE;
  }
  u->weight += weight;
  p->pos = pos;
  p->next = NULL;
  if (u->tail) {
    u->tail->next = p;
  } else {
    u->pos = p;
  }
  u->tail = p;
  u->tf++;
  return GRN_SUCCESS;
}

int
grn_ii_updspec_cmp(grn_ii_updspec *a, grn_ii_updspec *b)
{
  struct _grn_ii_pos *pa, *pb;
  if (a->rid != b->rid) { return a->rid - b->rid; }
  if (a->sid != b->sid) { return a->sid - b->sid; }
  if (a->weight != b->weight) { return a->weight - b->weight; }
  if (a->tf != b->tf) { return a->tf - b->tf; }
  for (pa = a->pos, pb = b->pos; pa && pb; pa = pa->next, pb = pb->next) {
    if (pa->pos != pb->pos) { return pa->pos - pb->pos; }
  }
  if (pa) { return 1; }
  if (pb) { return -1; }
  return 0;
}

grn_rc
grn_ii_updspec_close(grn_ctx *ctx, grn_ii_updspec *u)
{
  struct _grn_ii_pos *p = u->pos, *q;
  while (p) {
    q = p->next;
    GRN_FREE(p);
    p = q;
  }
  GRN_FREE(u);
  return GRN_SUCCESS;
}

grn_inline static uint8_t *
encode_rec(grn_ctx *ctx, grn_ii *ii, grn_ii_updspec *u, unsigned int *size, int deletep)
{
  uint8_t *br, *p;
  struct _grn_ii_pos *pp;
  uint32_t lpos, tf, weight;
  if (deletep) {
    tf = 0;
    weight = 0;
  } else {
    tf = u->tf;
    weight = u->weight;
  }
  if (!(br = GRN_MALLOC((tf + 4) * 5))) {
    return NULL;
  }
  p = br;
  GRN_B_ENC(u->rid, p);
  if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
    GRN_B_ENC(u->sid, p);
  } else {
    u->sid = 1;
  }
  GRN_B_ENC(tf, p);
  if ((ii->header.common->flags & GRN_OBJ_WITH_WEIGHT)) {
    GRN_B_ENC(weight, p);
  }
  if ((ii->header.common->flags & GRN_OBJ_WITH_POSITION)) {
    for (lpos = 0, pp = u->pos; pp && tf--; lpos = pp->pos, pp = pp->next) {
      GRN_B_ENC(pp->pos - lpos, p);
    }
  }
  while (((intptr_t)p & 0x03)) { *p++ = 0; }
  *size = (unsigned int) ((p - br) + sizeof(buffer_rec));
  return br;
}

typedef struct {
  grn_ii *ii;
  grn_hash *h;
} lexicon_deletable_arg;

#ifdef CASCADE_DELETE_LEXICON
static int
lexicon_deletable(grn_ctx *ctx, grn_obj *lexicon, grn_id tid, void *arg)
{
  uint32_t *a;
  grn_hash *h = ((lexicon_deletable_arg *)arg)->h;
  grn_ii *ii = ((lexicon_deletable_arg *)arg)->ii;
  if (!h) { return 0; }
  if ((a = array_at(ctx, ii, tid))) {
    if (a[0]) {
      array_unref(ctx, ii, tid);
      return 0;
    }
    array_unref(ctx, ii, tid);
  }
  {
    grn_ii_updspec **u;
    if (!grn_hash_get(ctx, h, &tid, sizeof(grn_id), (void **) &u)) {
      return (ERRP(ctx, GRN_ERROR)) ? 0 : 1;
    }
    if (!(*u)->tf || !(*u)->sid) { return 1; }
    return 0;
  }
}
#endif /* CASCADE_DELETE_LEXICON */

grn_inline static void
lexicon_delete(grn_ctx *ctx, grn_ii *ii, uint32_t tid, grn_hash *h)
{
#ifdef CASCADE_DELETE_LEXICON
  lexicon_deletable_arg arg = {ii, h};
  grn_table_delete_optarg optarg = {0, lexicon_deletable, &arg};
  _grn_table_delete_by_id(ctx, ii->lexicon, tid, &optarg);
#endif /* CASCADE_DELETE_LEXICON */
}

typedef struct {
  grn_id rid;
  uint32_t sid;
  uint32_t tf;
  uint32_t weight;
  uint32_t flags;
} docinfo;

static docinfo null_docinfo = {0};

typedef struct {
  uint32_t segno;
  uint32_t size;
  uint32_t dgap;
} chunk_info;

typedef struct {
  grn_log_level log_level;
  const char *tag;
  grn_ii *ii;
  buffer *buffer;
  const uint8_t *chunk;
  buffer_term *term;
  uint16_t nth_term;
  uint16_t n_terms;
  uint32_t nth_chunk;
  uint32_t n_chunks;
  datavec data_vector[MAX_N_ELEMENTS + 1];
  char name[GRN_TABLE_MAX_KEY_SIZE];
  int name_size;
  grn_obj inspected_term;
  grn_obj inspected_entries;
  uint32_t n_inspected_entries;
} merge_dump_source_data;

#define MERGE_DUMP_SOURCE_BATCH_SIZE 10

typedef enum {
  MERGE_DUMP_SOURCE_ENTRY_BUFFER,
  MERGE_DUMP_SOURCE_ENTRY_CHUNK,
} merge_dump_source_entry_type;

static void
merge_dump_source_flush_entries(grn_ctx *ctx,
                                merge_dump_source_data *data)
{
  if (GRN_TEXT_LEN(&(data->inspected_entries)) == 0) {
    return;
  }

  GRN_LOG(ctx, data->log_level,
          "%.*s",
          (int)GRN_TEXT_LEN(&(data->inspected_entries)),
          GRN_TEXT_VALUE(&(data->inspected_entries)));
  GRN_BULK_REWIND(&(data->inspected_entries));
  data->n_inspected_entries = 0;
}

static void
merge_dump_source_add_entry(grn_ctx *ctx,
                            merge_dump_source_data *data,
                            merge_dump_source_entry_type type,
                            docinfo *info,
                            uint8_t *position_gaps)
{
  if (GRN_TEXT_LEN(&(data->inspected_entries)) > 0) {
    GRN_TEXT_PUTC(ctx, &(data->inspected_entries), ' ');
  }
  grn_text_printf(ctx,
                  &(data->inspected_entries),
                  "(%u:%u:%u:%u)",
                  info->rid,
                  info->sid,
                  info->tf,
                  info->weight);
  if (data->ii->header.common->flags & GRN_OBJ_WITH_POSITION) {
    uint32_t i;
    uint32_t position = 0;

    GRN_TEXT_PUTC(ctx, &(data->inspected_entries), '[');
    for (i = 0; i < info->tf; i++) {
      uint32_t position_gap;

      if (i > 0) {
        GRN_TEXT_PUTC(ctx, &(data->inspected_entries), ',');
      }
      if (type == MERGE_DUMP_SOURCE_ENTRY_BUFFER) {
        GRN_B_DEC(position_gap, position_gaps);
      } else {
        position_gap = ((uint32_t *)position_gaps)[i];
      }
      position += position_gap;
      grn_text_printf(ctx,
                      &(data->inspected_entries),
                      "%u",
                      position);
    }
    GRN_TEXT_PUTC(ctx, &(data->inspected_entries), ']');
  }
  data->n_inspected_entries++;
  if (data->n_inspected_entries == MERGE_DUMP_SOURCE_BATCH_SIZE) {
    merge_dump_source_flush_entries(ctx, data);
  }
}

static void
merge_dump_source_chunk_raw(grn_ctx *ctx,
                            merge_dump_source_data *data,
                            const uint8_t *chunk_start,
                            const uint8_t *chunk_end)
{
  const uint8_t *chunk_current = chunk_start;
  int decoded_size;

  if ((chunk_end - chunk_current) == 0) {
    GRN_LOG(ctx, data->log_level,
            "%s[%.*s][%d/%d] <%.*s>(%u): %u/%u: no data",
            data->tag,
            data->name_size, data->name,
            data->nth_term, data->n_terms,
            (int)GRN_TEXT_LEN(&(data->inspected_term)),
            GRN_TEXT_VALUE(&(data->inspected_term)),
            data->term->tid & GRN_ID_MAX,
            data->nth_chunk, data->n_chunks);
    return;
  }

  decoded_size = grn_p_decv(ctx,
                            data->ii,
                            data->term->tid & GRN_ID_MAX,
                            chunk_current,
                            chunk_end - chunk_current,
                            data->data_vector,
                            data->ii->n_elements);
  if (decoded_size == 0) {
    GRN_LOG(ctx, data->log_level,
            "%s[%.*s][%d/%d] <%.*s>(%u): %u/%u: failed to decode",
            data->tag,
            data->name_size, data->name,
            data->nth_term, data->n_terms,
            (int)GRN_TEXT_LEN(&(data->inspected_term)),
            GRN_TEXT_VALUE(&(data->inspected_term)),
            data->term->tid & GRN_ID_MAX,
            data->nth_chunk, data->n_chunks);
    return;
  }

  {
    uint32_t n_documents;
    const uint32_t *record_id_gaps;
    const uint32_t *section_id_gaps = NULL;
    const uint32_t *n_terms_list;
    const uint32_t *weights = NULL;
    const uint32_t *position_gaps = NULL;

    {
      int i = 0;
      n_documents = data->data_vector[i].data_size;
      record_id_gaps = data->data_vector[i++].data;
      if (data->ii->header.common->flags & GRN_OBJ_WITH_SECTION) {
        section_id_gaps = data->data_vector[i++].data;
      }
      n_terms_list = data->data_vector[i++].data;
      if (data->ii->header.common->flags & GRN_OBJ_WITH_WEIGHT) {
        weights = data->data_vector[i++].data;
      }
      if (data->ii->header.common->flags & GRN_OBJ_WITH_POSITION) {
        position_gaps = data->data_vector[i++].data;
      }
    }

    {
      uint32_t i;
      grn_id record_id = GRN_ID_NIL;
      uint32_t section_id = 0;

      for (i = 0; i < n_documents; i++) {
        uint32_t record_id_gap = record_id_gaps[i];
        docinfo info;

        record_id += record_id_gap;
        info.rid = record_id;
        if (data->ii->header.common->flags & GRN_OBJ_WITH_SECTION) {
          if (record_id_gap > 0) {
            section_id = 0;
          }
          section_id += 1 + section_id_gaps[i];
        } else {
          section_id = 1;
        }
        info.sid = section_id;
        info.tf = 1 + n_terms_list[i];
        if (data->ii->header.common->flags & GRN_OBJ_WITH_WEIGHT) {
          info.weight = weights[i];
        } else {
          info.weight = 0;
        }

        merge_dump_source_add_entry(ctx,
                                    data,
                                    MERGE_DUMP_SOURCE_ENTRY_CHUNK,
                                    &info,
                                    (uint8_t *)position_gaps);
      }
      merge_dump_source_flush_entries(ctx, data);
    }
  }
}

static void
merge_dump_source_chunk(grn_ctx *ctx,
                        merge_dump_source_data *data)
{
  const uint8_t *chunk_start = data->chunk + data->term->pos_in_chunk;
  const uint8_t *chunk_end = chunk_start + data->term->size_in_chunk;

  if (data->term->tid & CHUNK_SPLIT) {
    const uint8_t *chunk_current = chunk_start;

    GRN_B_DEC(data->n_chunks, chunk_current);
    GRN_LOG(ctx, data->log_level,
            "%s[%.*s][%d/%d] <%.*s>(%u): chunk: %u",
            data->tag,
            data->name_size, data->name,
            data->nth_term, data->n_terms,
            (int)GRN_TEXT_LEN(&(data->inspected_term)),
            GRN_TEXT_VALUE(&(data->inspected_term)),
            data->term->tid & GRN_ID_MAX,
            data->n_chunks);

    for (data->nth_chunk = 0;
         data->nth_chunk < data->n_chunks;
         data->nth_chunk++) {
      chunk_info info;

      if (!(chunk_current < chunk_end)) {
        GRN_LOG(ctx, data->log_level,
                "%s[%.*s][%d/%d] <%.*s>(%u): chunk: %u/%u: no data",
                data->tag,
                data->name_size, data->name,
                data->nth_term, data->n_terms,
                (int)GRN_TEXT_LEN(&(data->inspected_term)),
                GRN_TEXT_VALUE(&(data->inspected_term)),
                data->term->tid & GRN_ID_MAX,
                data->nth_chunk, data->n_chunks);
        return;
      }

      GRN_B_DEC(info.segno, chunk_current);
      GRN_B_DEC(info.size, chunk_current);
      GRN_B_DEC(info.dgap, chunk_current);

      GRN_LOG(ctx, data->log_level,
              "%s[%.*s][%d/%d] <%.*s>(%u): chunk: %u/%u: "
              "segment:<%d>, size:<%d>, gap:<%d>",
              data->tag,
              data->name_size, data->name,
              data->nth_term, data->n_terms,
              (int)GRN_TEXT_LEN(&(data->inspected_term)),
              GRN_TEXT_VALUE(&(data->inspected_term)),
              data->term->tid & GRN_ID_MAX,
              data->nth_chunk, data->n_chunks,
              info.segno,
              info.size,
              info.dgap);
      if (info.size == 0) {
        continue;
      }
      {
        grn_io_win iw;
        uint8_t *sub_chunk;
        sub_chunk = WIN_MAP(ctx,
                            data->ii->chunk,
                            &iw,
                            info.segno,
                            0,
                            info.size,
                            GRN_IO_RDONLY);
        if (!sub_chunk) {
          GRN_LOG(ctx, data->log_level,
                  "%s[%.*s][%d/%d] <%.*s>(%u): chunk: "
                  "%u/%u: failed to open sub chunk",
                  data->tag,
                  data->name_size, data->name,
                  data->nth_term, data->n_terms,
                  (int)GRN_TEXT_LEN(&(data->inspected_term)),
                  GRN_TEXT_VALUE(&(data->inspected_term)),
                  data->term->tid & GRN_ID_MAX,
                  data->nth_chunk, data->n_chunks);
          continue;
        }
        merge_dump_source_chunk_raw(ctx,
                                    data,
                                    sub_chunk,
                                    sub_chunk + info.size);
        grn_io_win_unmap(ctx, &iw);
      }
    }
    if (chunk_current < chunk_end) {
      GRN_LOG(ctx, data->log_level,
              "%s[%.*s][%d/%d] <%.*s>(%u): chunk: %u",
              data->tag,
              data->name_size, data->name,
              data->nth_term, data->n_terms,
              (int)GRN_TEXT_LEN(&(data->inspected_term)),
              GRN_TEXT_VALUE(&(data->inspected_term)),
              data->term->tid & GRN_ID_MAX,
              data->n_chunks);
      merge_dump_source_chunk_raw(ctx,
                                  data,
                                  chunk_current,
                                  chunk_end);
    }
  } else {
    data->nth_chunk = 0;
    data->n_chunks = 0;
    GRN_LOG(ctx, data->log_level,
            "%s[%.*s][%d/%d] <%.*s>(%u): chunk: %u",
            data->tag,
            data->name_size, data->name,
            data->nth_term, data->n_terms,
            (int)GRN_TEXT_LEN(&(data->inspected_term)),
            GRN_TEXT_VALUE(&(data->inspected_term)),
            data->term->tid & GRN_ID_MAX,
            data->n_chunks);
    merge_dump_source_chunk_raw(ctx,
                                data,
                                chunk_start,
                                chunk_end);
  }
}

static void
merge_dump_source(grn_ctx *ctx,
                  grn_ii *ii,
                  buffer *buffer,
                  const uint8_t *chunk,
                  grn_log_level log_level)
{
  merge_dump_source_data data;

  if (!grn_logger_pass(ctx, log_level)) {
    return;
  }

  data.log_level = log_level;
  data.tag = "[ii][merge][source]";
  data.ii = ii;
  data.buffer = buffer;
  data.chunk = chunk;
  data.term = NULL;
  data.nth_term = 0;
  data.n_terms = buffer->header.nterms;
  data.nth_chunk = 0;
  data.n_chunks = 0;
  datavec_init(ctx, data.data_vector, ii->n_elements, 0, 0);
  if (ii->header.common->flags & GRN_OBJ_WITH_POSITION) {
    data.data_vector[ii->n_elements - 1].flags = ODD;
  }
  {
    GRN_DEFINE_NAME(ii);
    grn_memcpy(data.name, name, name_size);
    data.name_size = name_size;
  }
  GRN_TEXT_INIT(&(data.inspected_term), 0);
  GRN_TEXT_INIT(&(data.inspected_entries), 0);
  data.n_inspected_entries = 0;

  GRN_LOG(ctx, data.log_level,
          "%s[%.*s] %u",
          data.tag,
          data.name_size, data.name,
          data.n_terms);
  for (data.nth_term = 0; data.nth_term < data.n_terms; data.nth_term++) {
    uint16_t position;

    data.term = buffer->terms + data.nth_term;
    if (data.term->tid == 0) {
      GRN_LOG(ctx, data.log_level,
              "%s[%.*s][%d] void",
              data.tag,
              data.name_size, data.name,
              data.nth_term);
      continue;
    }

    GRN_BULK_REWIND(&(data.inspected_term));
    grn_ii_get_term(ctx,
                    ii,
                    data.term->tid & GRN_ID_MAX,
                    &(data.inspected_term));
    GRN_LOG(ctx, data.log_level,
            "%s[%.*s][%d/%d] <%.*s>(%u): chunk:<%u:%u>, buffer:<%u:%u>",
            data.tag,
            data.name_size, data.name,
            data.nth_term, data.n_terms,
            (int)GRN_TEXT_LEN(&(data.inspected_term)),
            GRN_TEXT_VALUE(&(data.inspected_term)),
            data.term->tid & GRN_ID_MAX,
            data.term->pos_in_chunk, data.term->size_in_chunk,
            data.term->pos_in_buffer, data.term->size_in_buffer);

    position = data.term->pos_in_buffer;
    while (position > 0) {
      buffer_rec *record = BUFFER_REC_AT(buffer, position);
      uint8_t *record_data = GRN_NEXT_ADDR(record);
      docinfo info;

      grn_text_printf(ctx,
                      &(data.inspected_entries),
                      "record: %u: <%u:%u%s>",
                      position,
                      record->step,
                      record->jump,
                      BUFFER_REC_DELETED(record) ? ":deleted" : "");

      position = record->step;

      if (BUFFER_REC_DELETED(record)) {
        merge_dump_source_flush_entries(ctx, &data);
        continue;
      }

      GRN_TEXT_PUTC(ctx,
                    &(data.inspected_entries),
                    ':');

      GRN_B_DEC(info.rid, record_data);
      if (ii->header.common->flags & GRN_OBJ_WITH_SECTION) {
        GRN_B_DEC(info.sid, record_data);
      } else {
        info.sid = 1;
      }
      GRN_B_DEC(info.tf, record_data);
      if (ii->header.common->flags & GRN_OBJ_WITH_WEIGHT) {
        GRN_B_DEC(info.weight, record_data);
      } else {
        info.weight = 0;
      }
      merge_dump_source_add_entry(ctx,
                                  &data,
                                  MERGE_DUMP_SOURCE_ENTRY_BUFFER,
                                  &info,
                                  record_data);
      merge_dump_source_flush_entries(ctx, &data);
    }

    if (chunk && data.term->size_in_chunk > 0) {
      merge_dump_source_chunk(ctx, &data);
    }
  }

  datavec_fin(ctx, data.data_vector);
  GRN_OBJ_FIN(ctx, &(data.inspected_term));
  GRN_OBJ_FIN(ctx, &(data.inspected_entries));
}

typedef struct {
  grn_ii *ii;
  bool succeeded;
  grn_obj source_chunks;
  grn_obj dest_chunks;
} grn_merging_data;

static void
grn_merging_data_init(grn_ctx *ctx,
                      grn_merging_data *data,
                      grn_ii *ii)
{
  data->ii = ii;
  data->succeeded = false;
  GRN_UINT32_INIT(&(data->source_chunks), GRN_OBJ_VECTOR);
  GRN_UINT32_INIT(&(data->dest_chunks), GRN_OBJ_VECTOR);
}

static void
grn_merging_data_fin(grn_ctx *ctx,
                     grn_merging_data *data)
{
  grn_obj *target_chunks;
  if (data->succeeded) {
    target_chunks = &(data->source_chunks);
  } else {
    target_chunks = &(data->dest_chunks);
  }
  const size_t n_target_chunks = GRN_UINT32_VECTOR_SIZE(target_chunks) / 2;
  size_t i;
  for (i = 0; i < n_target_chunks; i++) {
    const uint32_t segno = GRN_UINT32_VALUE_AT(target_chunks, i * 2);
    const uint32_t size = GRN_UINT32_VALUE_AT(target_chunks, i * 2 + 1);
    chunk_free(ctx, data->ii, segno, size);
  }
  GRN_OBJ_FIN(ctx, &(data->source_chunks));
  GRN_OBJ_FIN(ctx, &(data->dest_chunks));
}

static void
grn_merging_data_add_source_chunk(grn_ctx *ctx,
                                  grn_merging_data *data,
                                  uint32_t segno,
                                  uint32_t size)
{
  GRN_UINT32_PUT(ctx, &(data->source_chunks), segno);
  GRN_UINT32_PUT(ctx, &(data->source_chunks), size);
}

static void
grn_merging_data_add_dest_chunk(grn_ctx *ctx,
                                grn_merging_data *data,
                                uint32_t segno,
                                uint32_t size)
{
  GRN_UINT32_PUT(ctx, &(data->dest_chunks), segno);
  GRN_UINT32_PUT(ctx, &(data->dest_chunks), size);
}


typedef struct {
  buffer *buffer;
  const uint8_t *data;
  docinfo id;
  uint16_t next_position;
} merger_buffer_data;

typedef struct {
  const uint8_t *data_start;
  const uint8_t *data_end;
  const uint8_t *data;
  docinfo id;
  uint32_t n_documents;
  const uint32_t *record_id_gaps;
  const uint32_t *section_id_gaps;
  const uint32_t *tfs;
  const uint32_t *weights;
  const uint32_t *position_gaps;
  const uint32_t *position_gaps_end;
} merger_chunk_data;

typedef struct {
  grn_ii *ii;
  grn_id term_id;
  docinfo last_id;
  uint64_t position;
  grn_merging_data *merging_data;
  struct {
    merger_buffer_data buffer;
    merger_chunk_data chunk;
  } source;
  struct {
    uint32_t *record_id_gaps;
    uint32_t *section_id_gaps;
    uint32_t *tfs;
    uint32_t *weights;
    uint32_t *position_gaps;
    uint32_t *position_gaps_end;
  } dest;
} merger_data;

grn_inline static void
merger_init_chunk_data(grn_ctx *ctx,
                       merger_data *data,
                       datavec *rdv)
{
  merger_chunk_data *chunk_data = &(data->source.chunk);
  grn_ii *ii = data->ii;
  int j = 0;
  memset(&(chunk_data->id), 0, sizeof(docinfo));
  chunk_data->n_documents = rdv[j].data_size;
  chunk_data->record_id_gaps = rdv[j++].data;
  if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
    chunk_data->section_id_gaps = rdv[j++].data;
  }
  chunk_data->tfs = rdv[j++].data;
  if ((ii->header.common->flags & GRN_OBJ_WITH_WEIGHT)) {
    chunk_data->weights = rdv[j++].data;
  }
  chunk_data->position_gaps = rdv[j].data;
  chunk_data->position_gaps_end = chunk_data->position_gaps + rdv[j].data_size;
}

grn_inline static void
merger_report_error(grn_ctx *ctx,
                    merger_data *data,
                    const char *message,
                    docinfo *posting1,
                    docinfo *posting2)
{
  merger_buffer_data *buffer_data = &(data->source.buffer);
  merger_chunk_data *chunk_data = &(data->source.chunk);
  grn_obj term;
  GRN_DEFINE_NAME(data->ii);
  GRN_TEXT_INIT(&term, 0);
  grn_ii_get_term(ctx, data->ii, data->term_id & GRN_ID_MAX, &term);
  if (posting1 && posting2) {
    CRIT(GRN_FILE_CORRUPT,
         "[ii][broken] %s: <%.*s>: <%.*s>(%u): (%u:%u) -> (%u:%u)",
         message,
         name_size, name,
         (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
         data->term_id,
         posting1->rid, posting1->sid,
         posting2->rid, posting2->sid);
  } else {
    CRIT(GRN_FILE_CORRUPT,
         "[ii][broken] %s: <%.*s>: <%.*s>(%u): (%u:%u)",
         message,
         name_size, name,
         (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
         data->term_id,
         posting1->rid, posting1->sid);
  }
  GRN_OBJ_FIN(ctx, &term);
  merge_dump_source(ctx,
                    data->ii,
                    buffer_data->buffer,
                    chunk_data->data_start,
                    GRN_LOG_CRIT);
}

grn_inline static void
merger_get_next_chunk(grn_ctx *ctx, merger_data *data)
{
  merger_chunk_data *chunk_data = &(data->source.chunk);
  if (chunk_data->n_documents == 0) {
    chunk_data->id.rid = 0;
  } else {
    uint32_t record_id_gap = *chunk_data->record_id_gaps;
    chunk_data->record_id_gaps++;
    chunk_data->id.rid += record_id_gap;
    if (record_id_gap > 0) {
      chunk_data->id.sid = 0;
    }
    chunk_data->position_gaps += chunk_data->id.tf;
    chunk_data->id.tf = 1 + *chunk_data->tfs;
    chunk_data->tfs++;
    if ((data->ii->header.common->flags & GRN_OBJ_WITH_WEIGHT)) {
      chunk_data->id.weight = *chunk_data->weights;
      chunk_data->weights++;
    }
    if ((data->ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
      chunk_data->id.sid += 1 + *chunk_data->section_id_gaps;
      chunk_data->section_id_gaps++;
    } else {
      chunk_data->id.sid = 1;
    }
    chunk_data->n_documents--;
  }
}

grn_inline static void
merger_put_next_id(grn_ctx *ctx, merger_data *data, docinfo *id)
{
  uint32_t record_id_gap = id->rid - data->last_id.rid;
  *(data->dest.record_id_gaps) = record_id_gap;
  data->dest.record_id_gaps++;
  if ((data->ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
    uint32_t section_id_gap;
    if (record_id_gap > 0) {
      section_id_gap = id->sid - 1;
    } else {
      section_id_gap = id->sid - data->last_id.sid - 1;
    }
    *(data->dest.section_id_gaps) = section_id_gap;
    data->dest.section_id_gaps++;
  }
  *(data->dest.tfs) = id->tf - 1;
  data->dest.tfs++;
  if ((data->ii->header.common->flags & GRN_OBJ_WITH_WEIGHT)) {
    *(data->dest.weights) = id->weight;
    data->dest.weights++;
  }
  data->last_id.rid = id->rid;
  data->last_id.sid = id->sid;
}

grn_inline static void
merger_put_next_chunk(grn_ctx *ctx, merger_data *data)
{
  merger_chunk_data *chunk_data = &(data->source.chunk);
  if (chunk_data->id.rid > 0) {
    if (chunk_data->id.tf > 0) {
      if (data->last_id.rid > chunk_data->id.rid ||
          (data->last_id.rid == chunk_data->id.rid &&
           data->last_id.sid >= chunk_data->id.sid)) {
        merger_report_error(ctx,
                            data,
                            "the last posting is larger than "
                            "the next posting in chunk",
                            &(data->last_id),
                            &(chunk_data->id));
        return;
      }
      merger_put_next_id(ctx, data, &(chunk_data->id));
      if ((data->ii->header.common->flags & GRN_OBJ_WITH_POSITION)) {
        uint32_t i;
        uint32_t rest_n_positions =
          (uint32_t)(chunk_data->position_gaps_end -
                     chunk_data->position_gaps);
        uint32_t rest_n_dest_positions =
          (uint32_t)(data->dest.position_gaps_end -
                     data->dest.position_gaps);
        if (chunk_data->id.tf > rest_n_positions) {
          grn_obj term;
          GRN_DEFINE_NAME(data->ii);
          GRN_TEXT_INIT(&term, 0);
          grn_ii_get_term(ctx,
                          data->ii,
                          data->term_id & GRN_ID_MAX,
                          &term);
          GRN_LOG(ctx,
                  GRN_LOG_WARNING,
                  "[ii][merge][put][chunk] "
                  "the number of terms are larger than the number of positions: "
                  "<%.*s>: <%.*s>(%u): (%u:%u): (%u:%u)",
                  name_size, name,
                  (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                  data->term_id,
                  chunk_data->id.rid, chunk_data->id.sid,
                  chunk_data->id.tf,
                  rest_n_positions);
          GRN_OBJ_FIN(ctx, &term);
        }
        if (chunk_data->id.tf > rest_n_dest_positions) {
          /* TODO: Make this case error. */
          grn_obj term;
          GRN_DEFINE_NAME(data->ii);
          GRN_TEXT_INIT(&term, 0);
          grn_ii_get_term(ctx,
                          data->ii,
                          data->term_id & GRN_ID_MAX,
                          &term);
          GRN_LOG(ctx,
                  GRN_LOG_WARNING,
                  "[ii][merge][put][chunk] "
                  "the number of terms are larger than "
                  "the rest destination number of positions: "
                  "<%.*s>: <%.*s>(%u): (%u:%u): (%u:%u)",
                  name_size, name,
                  (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                  data->term_id,
                  chunk_data->id.rid, chunk_data->id.sid,
                  chunk_data->id.tf,
                  rest_n_dest_positions);
          GRN_OBJ_FIN(ctx, &term);
        }
        for (i = 0; i < chunk_data->id.tf; i++) {
          *(data->dest.position_gaps) = chunk_data->position_gaps[i];
          data->dest.position_gaps++;
          data->position += chunk_data->position_gaps[i];
        }
      }
    } else {
      merger_report_error(ctx,
                          data,
                          "invalid posting in chunk",
                          &(chunk_data->id),
                          NULL);
      return;
    }
  }
  merger_get_next_chunk(ctx, data);
}

grn_inline static void
merger_get_next_buffer(grn_ctx *ctx, merger_data *data)
{
  merger_buffer_data *buffer_data = &(data->source.buffer);
  if (buffer_data->next_position == 0) {
    buffer_data->id.rid = 0;
  } else {
    docinfo last_id = {
      buffer_data->id.rid,
      buffer_data->id.sid,
      0,
      0,
      0
    };
    buffer_rec *record = BUFFER_REC_AT(buffer_data->buffer,
                                       buffer_data->next_position);
    buffer_data->data = GRN_NEXT_ADDR(record);
    GRN_B_DEC(buffer_data->id.rid, buffer_data->data);
    if ((data->ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
      GRN_B_DEC(buffer_data->id.sid, buffer_data->data);
    } else {
      buffer_data->id.sid = 1;
    }
    if (last_id.rid > buffer_data->id.rid ||
        (last_id.rid == buffer_data->id.rid &&
         last_id.sid >= buffer_data->id.sid)) {
      merger_report_error(ctx,
                          data,
                          "postings in block aren't sorted",
                          &last_id,
                          &(buffer_data->id));
      return;
    }
    buffer_data->next_position = record->step;
  }
}

grn_inline static void
merger_put_next_buffer(grn_ctx *ctx, merger_data *data)
{
  merger_buffer_data *buffer_data = &(data->source.buffer);
  if (buffer_data->id.rid > 0 && buffer_data->id.sid > 0) {
    GRN_B_DEC(buffer_data->id.tf, buffer_data->data);
    if (buffer_data->id.tf > 0) {
      if (data->last_id.rid > buffer_data->id.rid ||
          (data->last_id.rid == buffer_data->id.rid &&
           data->last_id.sid >= buffer_data->id.sid)) {
        merger_report_error(ctx,
                            data,
                            "the last posting is larger than "
                            "the next posting in buffer",
                            &(data->last_id),
                            &(buffer_data->id));
        return;
      }
      if ((data->ii->header.common->flags & GRN_OBJ_WITH_WEIGHT)) {
        GRN_B_DEC(buffer_data->id.weight, buffer_data->data);
      }
      merger_put_next_id(ctx, data, &(buffer_data->id));
      if ((data->ii->header.common->flags & GRN_OBJ_WITH_POSITION)) {
         uint32_t rest_n_dest_positiongs =
          (uint32_t)(data->dest.position_gaps_end -
                     data->dest.position_gaps);
       if (buffer_data->id.tf > rest_n_dest_positiongs) {
          /* TODO: Make this case error. */
          merger_buffer_data *buffer_data = &(data->source.buffer);
          grn_obj term;
          GRN_DEFINE_NAME(data->ii);
          GRN_TEXT_INIT(&term, 0);
          grn_ii_get_term(ctx,
                          data->ii,
                          data->term_id & GRN_ID_MAX,
                          &term);
          GRN_LOG(ctx,
                  GRN_LOG_WARNING,
                  "[ii][merge][put][buffer] "
                  "the number of terms are larger than "
                  "the rest destination number of positions: "
                  "<%.*s>: <%.*s>(%u): (%u:%u): (%u:%u)",
                  name_size, name,
                  (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                  data->term_id,
                  buffer_data->id.rid, buffer_data->id.sid,
                  buffer_data->id.tf,
                  rest_n_dest_positiongs);
          GRN_OBJ_FIN(ctx, &term);
        }
        while (buffer_data->id.tf--) {
          GRN_B_DEC(*(data->dest.position_gaps), buffer_data->data);
          data->position += *(data->dest.position_gaps);
          data->dest.position_gaps++;
        }
      }
    }
  }
  merger_get_next_buffer(ctx, data);
}

grn_inline static grn_bool
merger_merge(grn_ctx *ctx, merger_data *data)
{
  merger_buffer_data *buffer_data = &(data->source.buffer);
  merger_chunk_data *chunk_data = &(data->source.chunk);
  if (buffer_data->id.rid > 0) {
    if (chunk_data->id.rid > 0) {
      if (chunk_data->id.rid < buffer_data->id.rid) {
        merger_put_next_chunk(ctx, data);
        if (ctx->rc != GRN_SUCCESS) { return GRN_FALSE; }
      } else {
        if (buffer_data->id.rid < chunk_data->id.rid) {
          merger_put_next_buffer(ctx, data);
          if (ctx->rc != GRN_SUCCESS) { return GRN_FALSE; }
        } else {
          if (buffer_data->id.sid > 0) {
            if (chunk_data->id.sid < buffer_data->id.sid) {
              merger_put_next_chunk(ctx, data);
              if (ctx->rc != GRN_SUCCESS) { return GRN_FALSE; }
            } else {
              if (buffer_data->id.sid == chunk_data->id.sid) {
                merger_get_next_chunk(ctx, data);
                if (ctx->rc != GRN_SUCCESS) { return GRN_FALSE; }
              }
              merger_put_next_buffer(ctx, data);
              if (ctx->rc != GRN_SUCCESS) { return GRN_FALSE; }
            }
          } else {
            merger_get_next_chunk(ctx, data);
            if (ctx->rc != GRN_SUCCESS) { return GRN_FALSE; }
          }
        }
      }
    } else {
      merger_put_next_buffer(ctx, data);
      if (ctx->rc != GRN_SUCCESS) { return GRN_FALSE; }
    }
  } else {
    if (chunk_data->id.rid > 0) {
      merger_put_next_chunk(ctx, data);
      if (ctx->rc != GRN_SUCCESS) { return GRN_FALSE; }
    } else {
      return GRN_FALSE;
    }
  }
  return GRN_TRUE;
}

static grn_rc
chunk_flush(grn_ctx *ctx, grn_ii *ii, chunk_info *cinfo, uint8_t *enc, uint32_t encsize)
{
  uint8_t *dc;
  uint32_t dcn;
  grn_io_win dw;
  if (encsize) {
    chunk_new(ctx, ii, &dcn, encsize);
    if (ctx->rc == GRN_SUCCESS) {
      if ((dc = WIN_MAP(ctx, ii->chunk, &dw, dcn, 0, encsize, GRN_IO_WRONLY))) {
        grn_memcpy(dc, enc, encsize);
        grn_io_win_unmap(ctx, &dw);
        cinfo->segno = dcn;
        cinfo->size = encsize;
      } else {
        chunk_free(ctx, ii, dcn, encsize);
        {
          GRN_DEFINE_NAME(ii);
          MERR("[ii][chunk][flush] failed to allocate a destination chunk: "
               "<%.*s>:"
               "segment:<%u>, size:<%u>",
               name_size, name,
               dcn, encsize);
        }
      }
    }
  } else {
    cinfo->segno = 0;
    cinfo->size = 0;
  }
  return ctx->rc;
}

static grn_rc
chunk_merge(grn_ctx *ctx,
            merger_data *data,
            chunk_info *cinfo,
            grn_id rid,
            datavec *dv,
            int32_t *balance)
{
  merger_buffer_data *buffer_data = &(data->source.buffer);
  merger_chunk_data *chunk_data = &(data->source.chunk);
  grn_ii *ii = data->ii;
  grn_io_win sw;
  uint32_t segno = cinfo->segno;
  uint32_t size = cinfo->size;
  uint32_t ndf = 0;
  const uint8_t *scp =
    WIN_MAP(ctx, ii->chunk, &sw, segno, 0, size, GRN_IO_RDONLY);
  datavec rdv[MAX_N_ELEMENTS + 1];
  size_t bufsize = S_SEGMENT * ii->n_elements;

  if (!scp) {
    grn_obj term;
    GRN_DEFINE_NAME(ii);
    GRN_TEXT_INIT(&term, 0);
    grn_ii_get_term(ctx, ii, data->term_id & GRN_ID_MAX, &term);
    MERR("[ii][chunk][merge] failed to allocate a source chunk: "
         "<%.*s>: "
         "<%.*s>(%u): "
         "record:<%u>, segment:<%u>, size:<%u>",
         name_size, name,
         (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
         data->term_id,
         rid,
         segno,
         size);
    GRN_OBJ_FIN(ctx, &term);
    return ctx->rc;
  }

  data->last_id = null_docinfo;
  chunk_data->section_id_gaps = NULL;
  chunk_data->weights = NULL;

  datavec_init(ctx, rdv, ii->n_elements, 0, 0);
  if (ctx->rc != GRN_SUCCESS) {
    grn_io_win_unmap(ctx, &sw);
    {
      GRN_DEFINE_NAME(ii);
      ERR(ctx->rc,
          "[ii][chunk][merge] failed to initialize data vector: <%.*s>",
          name_size, name);
    }
    return ctx->rc;
  }

  if ((ii->header.common->flags & GRN_OBJ_WITH_POSITION)) {
    rdv[ii->n_elements - 1].flags = ODD;
  }
  {
    int decoded_size;
    decoded_size = grn_p_decv(ctx, ii,
                              data->term_id & GRN_ID_MAX,
                              scp, cinfo->size, rdv, ii->n_elements);
    if (decoded_size == 0) {
      grn_obj term;
      grn_rc rc = ctx->rc;
      GRN_DEFINE_NAME(ii);
      GRN_TEXT_INIT(&term, 0);
      grn_ii_get_term(ctx, ii, data->term_id & GRN_ID_MAX, &term);
      if (rc == GRN_SUCCESS) {
        rc = GRN_UNKNOWN_ERROR;
      }
      ERR(rc,
          "[ii][chunk][merge] failed to decode: "
          "<%.*s>: "
          "<%.*s>(%u): "
          "<%u>: "
          "<%u>",
          name_size, name,
          (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
          data->term_id,
          rid,
          cinfo->size);
      GRN_OBJ_FIN(ctx, &term);
      goto exit;
    }
    bufsize += decoded_size;
  }
  merger_init_chunk_data(ctx, data, rdv);
  /* (df in chunk list) = a[1] - chunk_data->n_documents; */
  datavec_reset(ctx,
                dv,
                ii->n_elements,
                chunk_data->n_documents + S_SEGMENT,
                bufsize);
  if (ctx->rc != GRN_SUCCESS) {
    grn_obj term;
    GRN_DEFINE_NAME(ii);
    GRN_TEXT_INIT(&term, 0);
    grn_ii_get_term(ctx, ii, data->term_id & GRN_ID_MAX, &term);
    ERR(ctx->rc,
        "[ii][chunk][merge] failed to reset data vector: "
        "<%.*s>: "
        "<%.*s>(%u)",
        name_size, name,
        (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
        data->term_id);
    GRN_OBJ_FIN(ctx, &term);
    goto exit;
  }
  {
    int j = 0;
    data->dest.record_id_gaps = dv[j++].data;
    if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
      data->dest.section_id_gaps = dv[j++].data;
    }
    data->dest.tfs = dv[j++].data;
    if ((ii->header.common->flags & GRN_OBJ_WITH_WEIGHT)) {
      data->dest.weights = dv[j++].data;
    }
    data->dest.position_gaps = dv[j++].data;
    data->dest.position_gaps_end = dv[j].data;
  }
  merger_get_next_chunk(ctx, data);
  if (ctx->rc != GRN_SUCCESS) {
    grn_obj term;
    GRN_DEFINE_NAME(ii);
    GRN_TEXT_INIT(&term, 0);
    grn_ii_get_term(ctx, ii, data->term_id & GRN_ID_MAX, &term);
    ERR(ctx->rc,
        "[ii][chunk][merge] failed to get the next chunk posting: "
        "<%.*s>: "
        "<%.*s>(%u)",
        name_size, name,
        (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
        data->term_id);
    GRN_OBJ_FIN(ctx, &term);
    goto exit;
  }
  data->position = 0;
  do {
    if (!merger_merge(ctx, data)) {
      break;
    }
  } while (buffer_data->id.rid <= rid || chunk_data->id.rid);
  if (ctx->rc != GRN_SUCCESS) {
    grn_obj term;
    GRN_DEFINE_NAME(ii);
    GRN_TEXT_INIT(&term, 0);
    grn_ii_get_term(ctx, ii, data->term_id & GRN_ID_MAX, &term);
    ERR(ctx->rc,
        "[ii][chunk][merge] failed to merge: "
        "<%.*s>: "
        "<%.*s>(%u)",
        name_size, name,
        (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
        data->term_id);
    GRN_OBJ_FIN(ctx, &term);
    goto exit;
  }
  ndf = data->dest.record_id_gaps - dv[0].data;
  {
    int j = 0;
    uint8_t *enc;
    uint32_t f_s = (ndf < 3) ? 0 : USE_P_ENC;
    uint32_t f_d = ((ndf < 16) || (ndf <= (data->last_id.rid >> 8))) ? 0 : USE_P_ENC;
    dv[j].data_size = ndf; dv[j++].flags = f_d;
    if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
      dv[j].data_size = ndf; dv[j++].flags = f_s;
    }
    dv[j].data_size = ndf; dv[j++].flags = f_s;
    if ((ii->header.common->flags & GRN_OBJ_WITH_WEIGHT)) {
      dv[j].data_size = ndf; dv[j++].flags = f_s;
    }
    if ((ii->header.common->flags & GRN_OBJ_WITH_POSITION)) {
      const uint32_t n_positions =
        data->dest.position_gaps - dv[j].data;
      uint32_t f_p;
      if ((n_positions < 32) || (n_positions <= (data->position >> 13))) {
        f_p = 0;
      } else {
        f_p = USE_P_ENC;
      }
      dv[j].data_size = n_positions; dv[j].flags = f_p|ODD;
    }
    const ssize_t encsize_estimated = grn_p_encv(ctx, dv, ii->n_elements, NULL);
    if (encsize_estimated == -1) {
      grn_obj term;
      GRN_DEFINE_NAME(ii);
      GRN_TEXT_INIT(&term, 0);
      grn_ii_get_term(ctx, ii, data->term_id & GRN_ID_MAX, &term);
      MERR("[ii][chunk][merge] failed to estimate encode buffer size: "
           "<%.*s>: "
           "<%.*s>(%u): "
           "record:<%u>, "
           "segment:<%u>, "
           "size:<%u>, "
           "estimated-buffer-size: <%" GRN_FMT_SSIZE ">",
           name_size, name,
           (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
           data->term_id,
           rid,
           segno,
           size,
           encsize_estimated);
      GRN_OBJ_FIN(ctx, &term);
      goto exit;
    }
    if (encsize_estimated == 0) {
      chunk_flush(ctx, ii, cinfo, NULL, 0);
    } else {
      enc = GRN_MALLOC(encsize_estimated);
      if (!enc) {
        grn_obj term;
        GRN_DEFINE_NAME(ii);
        GRN_TEXT_INIT(&term, 0);
        grn_ii_get_term(ctx, ii, data->term_id & GRN_ID_MAX, &term);
        MERR("[ii][chunk][merge] failed to allocate a encode buffer: "
             "<%.*s>: "
             "<%.*s>(%u): "
             "record:<%u>, "
             "segment:<%u>, "
             "size:<%u>, "
             "estimated-buffer-size: <%" GRN_FMT_SSIZE ">",
             name_size, name,
             (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
             data->term_id,
             rid,
             segno,
             size,
             encsize_estimated);
        GRN_OBJ_FIN(ctx, &term);
        goto exit;
      }
      const ssize_t encsize = grn_p_encv(ctx, dv, ii->n_elements, enc);
      if (encsize == -1) {
        grn_obj term;
        GRN_DEFINE_NAME(ii);
        GRN_TEXT_INIT(&term, 0);
        grn_ii_get_term(ctx, ii, data->term_id & GRN_ID_MAX, &term);
        MERR("[ii][chunk][merge] failed to encode: "
             "<%.*s>: "
             "<%.*s>(%u): "
             "record:<%u>, "
             "segment:<%u>, "
             "size:<%u>, "
             "estimated-buffer-size: <%" GRN_FMT_SSIZE ">",
             name_size, name,
             (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
             data->term_id,
             rid,
             segno,
             size,
             encsize_estimated);
        GRN_OBJ_FIN(ctx, &term);
        GRN_FREE(enc);
        goto exit;
      }
      chunk_flush(ctx, ii, cinfo, enc, encsize);
      if (ctx->rc == GRN_SUCCESS) {
        grn_merging_data_add_dest_chunk(ctx,
                                        data->merging_data,
                                        cinfo->segno,
                                        cinfo->size);
      }
      GRN_FREE(enc);
    }
    if (ctx->rc != GRN_SUCCESS) {
      goto exit;
    }
    grn_merging_data_add_source_chunk(ctx, data->merging_data, segno, size);
  }
  *balance += (ndf - chunk_data->n_documents);

exit :
  datavec_fin(ctx, rdv);
  grn_io_win_unmap(ctx, &sw);

  return ctx->rc;
}

static void
buffer_merge_dump_datavec(grn_ctx *ctx,
                          grn_ii *ii,
                          datavec *dv,
                          datavec *rdv)
{
  uint32_t i, j;
  grn_obj buffer;

  GRN_TEXT_INIT(&buffer, 0);
  for (i = 0; i < ii->n_elements; i++) {
    GRN_LOG(ctx, GRN_LOG_DEBUG, "rdv[%d] data_size=%d, flags=%d",
            i, rdv[i].data_size, rdv[i].flags);
    GRN_BULK_REWIND(&buffer);
    for (j = 0; j < rdv[i].data_size;) {
      grn_text_printf(ctx, &buffer, " %d", rdv[i].data[j]);
      j++;
      if (!(j % 32) || j == rdv[i].data_size) {
        GRN_LOG(ctx, GRN_LOG_DEBUG,
                "rdv[%d].data[%d]%.*s",
                i, j,
                (int)GRN_TEXT_LEN(&buffer),
                GRN_TEXT_VALUE(&buffer));
        GRN_BULK_REWIND(&buffer);
      }
    }
  }

  for (i = 0; i < ii->n_elements; i++) {
    GRN_LOG(ctx, GRN_LOG_DEBUG, "dv[%d] data_size=%d, flags=%d",
            i, dv[i].data_size, dv[i].flags);
    GRN_BULK_REWIND(&buffer);
    for (j = 0; j < dv[i].data_size;) {
      grn_text_printf(ctx, &buffer, " %d", dv[i].data[j]);
      j++;
      if (!(j % 32) || j == dv[i].data_size) {
        GRN_LOG(ctx, GRN_LOG_DEBUG,
                "dv[%d].data[%d]%.*s",
                i, j,
                (int)GRN_TEXT_LEN(&buffer),
                GRN_TEXT_VALUE(&buffer));
        GRN_BULK_REWIND(&buffer);
      }
    }
  }

  GRN_OBJ_FIN(ctx, &buffer);
}

static void
buffer_merge_ensure_dc(grn_ctx *ctx,
                       grn_ii *ii,
                       uint8_t **dc,
                       uint8_t **dcp,
                       size_t *dc_size,
                       size_t required_size,
                       const char *tag)
{
  size_t dc_used_size = *dcp - *dc;
  if (required_size <= (*dc_size - dc_used_size)) {
    return;
  }

  size_t new_dc_size = *dc_size * 2;
  while (required_size > (new_dc_size - dc_used_size)) {
    new_dc_size *= 2;
  }
  uint8_t *new_dc = GRN_REALLOC(*dc, new_dc_size);
  if (new_dc) {
    GRN_DEFINE_NAME(ii);
    GRN_LOG(ctx,
            GRN_LOG_INFO,
            "[ii][buffer][merge]%s destination chunk is expanded: "
            "<%.*s>: "
            "<%" GRN_FMT_SIZE "> -> <%" GRN_FMT_SIZE ">",
            tag,
            name_size, name,
            *dc_size,
            new_dc_size);
    *dcp = new_dc + dc_used_size;
    *dc = new_dc;
    *dc_size = new_dc_size;
  } else {
    grn_rc rc = ctx->rc;
    if (rc == GRN_SUCCESS) {
      rc = GRN_NO_MEMORY_AVAILABLE;
    }
    GRN_DEFINE_NAME(ii);
    ERR(rc,
        "[ii][buffer][merge]%s failed to expand destination chunk: "
        "<%.*s>: "
        "<%" GRN_FMT_SIZE "> -> <%" GRN_FMT_SIZE ">",
        tag,
        name_size, name,
        *dc_size,
        new_dc_size);
  }
}

static grn_rc
buffer_merge(grn_ctx *ctx,
             grn_ii *ii,
             uint32_t seg,
             grn_hash *h,
             buffer *sb,
             const uint8_t *sc,
             buffer *db,
             uint8_t **dc_output,
             grn_merging_data *merging_data)
{
  buffer_term *bt;
  uint8_t *dc = NULL;
  uint8_t *dcp = NULL;
  datavec dv[MAX_N_ELEMENTS + 1];
  datavec rdv[MAX_N_ELEMENTS + 1];
  uint16_t n = db->header.nterms, nterms_void = 0;
  size_t unitsize = (S_SEGMENT + sb->header.chunk_size / sb->header.nterms) * 2;
  // size_t unitsize = (S_SEGMENT + sb->header.chunk_size) * 2 + (1<<24);
  size_t totalsize = unitsize * ii->n_elements;

  //todo : realloc
  datavec_init(ctx, dv, ii->n_elements, unitsize, totalsize);
  if (ctx->rc != GRN_SUCCESS) {
    GRN_DEFINE_NAME(ii);
    ERR(ctx->rc,
        "[ii][buffer][merge] failed to initialize data vector: "
        "<%.*s>: "
        "unit-size:<%" GRN_FMT_SIZE ">, "
        "total-size:<%" GRN_FMT_SIZE ">",
        name_size, name,
        unitsize,
        totalsize);
    return ctx->rc;
  }
  datavec_init(ctx, rdv, ii->n_elements, 0, 0);
  if (ctx->rc != GRN_SUCCESS) {
    datavec_fin(ctx, dv);
    GRN_DEFINE_NAME(ii);
    ERR(ctx->rc,
        "[ii][buffer][merge] failed to initialize data vector for read: "
        "<%.*s>",
        name_size, name);
    return ctx->rc;
  }
  if ((ii->header.common->flags & GRN_OBJ_WITH_POSITION)) {
    rdv[ii->n_elements - 1].flags = ODD;
  }

  size_t dc_size = (sb->header.chunk_size + S_SEGMENT) * 2;
  dc = GRN_MALLOC(dc_size);
  if (!dc) {
    grn_rc rc = ctx->rc;
    if (rc == GRN_SUCCESS) {
      rc = GRN_NO_MEMORY_AVAILABLE;
    }
    GRN_DEFINE_NAME(ii);
    ERR(rc,
        "[ii][buffer][merge] failed to allocate destination chunk: "
        "<%.*s>: <%" GRN_FMT_SIZE ">",
        name_size, name,
        dc_size);
    goto exit;
  }
  dcp = dc;

  for (bt = db->terms; n; n--, bt++) {
    merger_data data = {0};
    merger_buffer_data *buffer_data = &(data.source.buffer);
    merger_chunk_data *chunk_data = &(data.source.chunk);
    int32_t balance = 0;
    uint32_t nchunks = 0;
    uint32_t nvchunks = 0;
    chunk_info *cinfo = NULL;
    grn_id crid = GRN_ID_NIL;

    if (!bt->tid) {
      nterms_void++;
      continue;
    }

    data.ii = ii;
    data.term_id = bt->tid;
    data.merging_data = merging_data;
    buffer_data->buffer = sb;
    chunk_data->data_start = sc;

    if (bt->pos_in_buffer == 0) {
      if (bt->size_in_buffer > 0) {
        grn_obj term;
        GRN_DEFINE_NAME(ii);
        GRN_TEXT_INIT(&term, 0);
        grn_ii_get_term(ctx, ii, bt->tid & GRN_ID_MAX, &term);
        GRN_LOG(ctx,
                GRN_WARN,
                "[ii][buffer][merge] invalid size for buffer term: "
                "<%.*s>: "
                "<%.*s>(%u): "
                "size:<%u>",
                name_size, name,
                (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                bt->tid,
                bt->size_in_buffer);
        GRN_OBJ_FIN(ctx, &term);
        goto exit;
      }
      if (bt->size_in_chunk > 0) {
        buffer_merge_ensure_dc(ctx,
                               ii,
                               &dc,
                               &dcp,
                               &dc_size,
                               bt->size_in_chunk,
                               "[copy-chunk]");
        if (ctx->rc != GRN_SUCCESS) {
          goto exit;
        }
        grn_memcpy(dcp,
                   chunk_data->data_start + bt->pos_in_chunk,
                   bt->size_in_chunk);
        bt->pos_in_chunk = (uint32_t)(dcp - dc);
        dcp += bt->size_in_chunk;
      }
      continue;
    }

    buffer_data->next_position = bt->pos_in_buffer;
    merger_get_next_buffer(ctx, &data);
    if (ctx->rc != GRN_SUCCESS) {
      goto exit;
    }
    if (chunk_data->data_start && bt->size_in_chunk > 0) {
      size_t size = S_SEGMENT * ii->n_elements;
      chunk_data->data = chunk_data->data_start + bt->pos_in_chunk;
      chunk_data->data_end = chunk_data->data + bt->size_in_chunk;
      if ((bt->tid & CHUNK_SPLIT)) {
        uint32_t i;
        GRN_B_DEC(nchunks, chunk_data->data);
        if (!(cinfo = GRN_MALLOCN(chunk_info, nchunks + 1))) {
          grn_obj term;
          GRN_DEFINE_NAME(ii);
          GRN_TEXT_INIT(&term, 0);
          grn_ii_get_term(ctx, ii, bt->tid & GRN_ID_MAX, &term);
          MERR("[ii][buffer][merge] failed to allocate chunk info: "
               "<%.*s>: "
               "<%.*s>(%u): "
               "segment:<%u>, "
               "n-chunks:<%u>, "
               "unit-size:<%" GRN_FMT_SIZE ">, "
               "total-size:<%" GRN_FMT_SIZE ">",
               name_size, name,
               (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
               bt->tid,
               seg,
               nchunks,
               unitsize,
               totalsize);
          GRN_OBJ_FIN(ctx, &term);
          goto exit;
        }
        grn_id dgap_keep = GRN_ID_NIL;
        for (i = 0; i < nchunks; i++) {
          GRN_B_DEC(cinfo[i].segno, chunk_data->data);
          GRN_B_DEC(cinfo[i].size, chunk_data->data);
          GRN_B_DEC(cinfo[i].dgap, chunk_data->data);
          crid += cinfo[i].dgap;
          if (buffer_data->id.rid <= crid) {
            chunk_merge(ctx, &data, &cinfo[i], crid, dv, &balance);
            if (ctx->rc != GRN_SUCCESS) {
              if (cinfo) { GRN_FREE(cinfo); }
              {
                grn_obj term;
                GRN_DEFINE_NAME(ii);
                GRN_TEXT_INIT(&term, 0);
                grn_ii_get_term(ctx, ii, bt->tid & GRN_ID_MAX, &term);
                ERR(ctx->rc,
                    "[ii][buffer][merge] failed to merge chunk: "
                    "<%.*s>: "
                    "<%.*s>(%u): "
                    "chunk:<%u>, "
                    "n-chunks:<%u>",
                    name_size, name,
                    (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                    bt->tid,
                    i,
                    nchunks);
                GRN_OBJ_FIN(ctx, &term);
              }
              goto exit;
            }
          }
          if (cinfo[i].size == 0) {
            dgap_keep += cinfo[i].dgap;
          } else {
            cinfo[i].dgap += dgap_keep;
            dgap_keep = GRN_ID_NIL;
            nvchunks++;
          }
        }
      }
      if (chunk_data->data_end > chunk_data->data) {
        int decoded_size;
        decoded_size = grn_p_decv(ctx,
                                  ii,
                                  bt->tid & GRN_ID_MAX,
                                  chunk_data->data,
                                  chunk_data->data_end - chunk_data->data,
                                  rdv,
                                  ii->n_elements);
        if (decoded_size == 0) {
          if (cinfo) { GRN_FREE(cinfo); }
          {
            grn_obj term;
            grn_rc rc = ctx->rc;
            GRN_DEFINE_NAME(ii);
            GRN_TEXT_INIT(&term, 0);
            grn_ii_get_term(ctx, ii, bt->tid & GRN_ID_MAX, &term);
            if (rc == GRN_SUCCESS) {
              rc = GRN_UNKNOWN_ERROR;
            }
            ERR(rc,
                "[ii][buffer][merge] failed to decode: "
                "<%.*s>: "
                "<%.*s>(%u): "
                "n-chunks:<%u>",
                name_size, name,
                (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                bt->tid,
                nvchunks);
            GRN_OBJ_FIN(ctx, &term);
          }
          goto exit;
        }
        size += decoded_size;
        merger_init_chunk_data(ctx, &data, rdv);
        datavec_reset(ctx,
                      dv,
                      ii->n_elements,
                      chunk_data->n_documents + S_SEGMENT,
                      size);
        if (ctx->rc != GRN_SUCCESS) {
          if (cinfo) { GRN_FREE(cinfo); }
          {
            grn_obj term;
            GRN_DEFINE_NAME(ii);
            GRN_TEXT_INIT(&term, 0);
            grn_ii_get_term(ctx, ii, bt->tid & GRN_ID_MAX, &term);
            ERR(ctx->rc,
                "[ii][buffer][merge] failed to reset data vector: "
                "<%.*s>: "
                "<%.*s>(%u): "
                "unit-size:<%" GRN_FMT_SIZE ">, "
                "total-size:<%" GRN_FMT_SIZE ">",
                name_size, name,
                (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                bt->tid,
                (size_t)(chunk_data->n_documents + S_SEGMENT),
                size);
            GRN_OBJ_FIN(ctx, &term);
          }
          goto exit;
        }
      }
    }
    {
      int j = 0;
      data.dest.record_id_gaps = dv[j++].data;
      if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
        data.dest.section_id_gaps = dv[j++].data;
      }
      data.dest.tfs = dv[j++].data;
      if ((ii->header.common->flags & GRN_OBJ_WITH_WEIGHT)) {
        data.dest.weights = dv[j++].data;
      }
      data.dest.position_gaps = dv[j++].data;
      data.dest.position_gaps_end = dv[j].data;
    }
    data.last_id = null_docinfo;
    merger_get_next_chunk(ctx, &data);
    if (ctx->rc != GRN_SUCCESS) {
      if (cinfo) { GRN_FREE(cinfo); }
      goto exit;
    }
    data.position = 0;
    while (merger_merge(ctx, &data)) {
    }
    if (ctx->rc != GRN_SUCCESS) {
      if (cinfo) { GRN_FREE(cinfo); }
      {
        grn_obj term;
        GRN_DEFINE_NAME(ii);
        GRN_TEXT_INIT(&term, 0);
        grn_ii_get_term(ctx, ii, bt->tid & GRN_ID_MAX, &term);
        ERR(ctx->rc,
            "[ii][buffer][merge] failed to merge chunk: "
            "<%.*s>: "
            "<%.*s>(%u)",
            name_size, name,
            (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
            bt->tid);
        GRN_OBJ_FIN(ctx, &term);
      }
      goto exit;
    }
    {
      /* TODO: Is n_documents better? */
      uint32_t ndf = data.dest.record_id_gaps - dv[0].data;
      grn_id tid = bt->tid & GRN_ID_MAX;
      uint32_t *a = array_at(ctx, ii, tid);
      if (!a) {
        /* TODO: warning */
        GRN_LOG(ctx, GRN_LOG_DEBUG, "array_entry not found tid=%d", tid);
        memset(bt, 0, sizeof(buffer_term));
        nterms_void++;
      } else {
        if (!ndf && !nvchunks) {
          a[0] = 0;
          a[1] = 0;
          lexicon_delete(ctx, ii, tid, h);
          memset(bt, 0, sizeof(buffer_term));
          nterms_void++;
        } else if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION) &&
                   !nvchunks &&
                   ndf == 1 &&
                   data.last_id.rid < 0x100000 &&
                   data.last_id.sid < 0x800 &&
                   data.last_id.tf == 1 &&
                   data.last_id.weight == 0) {
          a[0] = POS_EMBED_RID_SID(data.last_id.rid, data.last_id.sid);
          if (ii->header.common->flags & GRN_OBJ_WITH_POSITION) {
            a[1] = data.dest.position_gaps[-1];
          } else {
            a[1] = 0;
          }
          memset(bt, 0, sizeof(buffer_term));
          nterms_void++;
        } else if (!(ii->header.common->flags & GRN_OBJ_WITH_SECTION) &&
                   !nvchunks &&
                   ndf == 1 &&
                   data.last_id.tf == 1 &&
                   data.last_id.weight == 0) {
          a[0] = POS_EMBED_RID(data.last_id.rid);
          if (ii->header.common->flags & GRN_OBJ_WITH_POSITION) {
            a[1] = data.dest.position_gaps[-1];
          } else {
            a[1] = 0;
          }
          memset(bt, 0, sizeof(buffer_term));
          nterms_void++;
        } else {
          int j = 0;
          uint32_t f_s = (ndf < 3) ? 0 : USE_P_ENC;
          uint32_t f_d = ((ndf < 16) || (ndf <= (data.last_id.rid >> 8))) ? 0 : USE_P_ENC;
          dv[j].data_size = ndf; dv[j++].flags = f_d;
          if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
            dv[j].data_size = ndf; dv[j++].flags = f_s;
          }
          dv[j].data_size = ndf; dv[j++].flags = f_s;
          if ((ii->header.common->flags & GRN_OBJ_WITH_WEIGHT)) {
            dv[j].data_size = ndf; dv[j++].flags = f_s;
          }
          if ((ii->header.common->flags & GRN_OBJ_WITH_POSITION)) {
            const uint32_t n_positions = data.dest.position_gaps - dv[j].data;
            uint32_t f_p;
            if ((n_positions < 32) || (n_positions <= (data.position >> 13))) {
              f_p = 0;
            } else {
              f_p = USE_P_ENC;
            }
            dv[j].data_size = n_positions; dv[j].flags = f_p|ODD;
          }

          const size_t dc_offset = dcp - dc;
          a[1] =
            (bt->size_in_chunk ? a[1] : 0) +
            (ndf - chunk_data->n_documents) +
            balance;
          if (nvchunks) {
            buffer_merge_ensure_dc(ctx,
                                   ii,
                                   &dc,
                                   &dcp,
                                   &dc_size,
                                   GRN_B_ENC_MAX_SIZE * (1 + 3 * nchunks),
                                   "[encode-chunk-metadata]");
            if (ctx->rc != GRN_SUCCESS) {
              if (cinfo) { GRN_FREE(cinfo); }
              array_unref(ctx, ii, tid);
              goto exit;
            }
            GRN_B_ENC(nvchunks, dcp);
            for (uint32_t i = 0; i < nchunks; i++) {
              if (cinfo[i].size) {
                GRN_B_ENC(cinfo[i].segno, dcp);
                GRN_B_ENC(cinfo[i].size, dcp);
                GRN_B_ENC(cinfo[i].dgap, dcp);
              }
            }
          }
          const ssize_t estimated_encsize = grn_p_encv(ctx,
                                                       dv,
                                                       ii->n_elements,
                                                       NULL);
          if (estimated_encsize == -1) {
            grn_obj term;
            GRN_DEFINE_NAME(ii);
            GRN_TEXT_INIT(&term, 0);
            grn_ii_get_term(ctx, ii, bt->tid & GRN_ID_MAX, &term);
            ERR(ctx->rc,
                "[ii][buffer][merge] failed to estimate encode buffer size: "
                "<%.*s>: "
                "<%.*s>(%u)",
                name_size, name,
                (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                bt->tid);
            GRN_OBJ_FIN(ctx, &term);
            buffer_merge_dump_datavec(ctx, ii, dv, rdv);
            if (cinfo) { GRN_FREE(cinfo); }
            array_unref(ctx, ii, tid);
            goto exit;
          }
          buffer_merge_ensure_dc(ctx,
                                 ii,
                                 &dc,
                                 &dcp,
                                 &dc_size,
                                 estimated_encsize,
                                 "[encode-data-vector]");
          if (ctx->rc != GRN_SUCCESS) {
            buffer_merge_dump_datavec(ctx, ii, dv, rdv);
            if (cinfo) { GRN_FREE(cinfo); }
            array_unref(ctx, ii, tid);
            goto exit;
          }

          const ssize_t encsize = grn_p_encv(ctx, dv, ii->n_elements, dcp);
          if (encsize == -1) {
            grn_obj term;
            GRN_DEFINE_NAME(ii);
            GRN_TEXT_INIT(&term, 0);
            grn_ii_get_term(ctx, ii, bt->tid & GRN_ID_MAX, &term);
            ERR(ctx->rc,
                "[ii][buffer][merge] failed to encode: "
                "<%.*s>: "
                "<%.*s>(%u): "
                "<%" GRN_FMT_SSIZE ">",
                name_size, name,
                (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                bt->tid,
                estimated_encsize);
            GRN_OBJ_FIN(ctx, &term);
            buffer_merge_dump_datavec(ctx, ii, dv, rdv);
            if (cinfo) { GRN_FREE(cinfo); }
            array_unref(ctx, ii, tid);
            goto exit;
          }

          if (encsize > CHUNK_SPLIT_THRESHOLD &&
              (cinfo || (cinfo = GRN_MALLOCN(chunk_info, nchunks + 1))) &&
              !chunk_flush(ctx, ii, &cinfo[nchunks], dcp, encsize)) {
            uint32_t i;
            cinfo[nchunks].dgap = data.last_id.rid - crid;
            nvchunks++;
            dcp = dc + dc_offset;
            GRN_B_ENC(nvchunks, dcp);
            for (i = 0; i <= nchunks; i++) {
              if (cinfo[i].size) {
                GRN_B_ENC(cinfo[i].segno, dcp);
                GRN_B_ENC(cinfo[i].size, dcp);
                GRN_B_ENC(cinfo[i].dgap, dcp);
              }
            }
            /* TODO: format */
            GRN_LOG(ctx,
                    GRN_LOG_DEBUG,
                    "split (%d) encsize=%" GRN_FMT_SSIZE,
                    tid, encsize);
            bt->tid |= CHUNK_SPLIT;
          } else {
            dcp += encsize;
            if (!nvchunks) {
              bt->tid &= ~CHUNK_SPLIT;
            }
          }
          bt->pos_in_chunk = (uint32_t)dc_offset;
          bt->size_in_chunk = (uint32_t)(dcp - (dc + dc_offset));
          bt->size_in_buffer = 0;
          bt->pos_in_buffer = 0;
        }
        array_unref(ctx, ii, tid);
      }
    }
    if (cinfo) { GRN_FREE(cinfo); }
  }
  db->header.chunk_size = (uint32_t)(dcp - dc);
  db->header.buffer_free =
    S_SEGMENT - sizeof(buffer_header) - db->header.nterms * sizeof(buffer_term);
  db->header.nterms_void = nterms_void;

  if (grn_ii_dump_index_source_on_merge) {
    merge_dump_source(ctx, ii, sb, sc, GRN_LOG_DEBUG);
  }

exit :
  if (ctx->rc == GRN_SUCCESS) {
    *dc_output = dc;
  } else {
    if (dc) {
      GRN_FREE(dc);
    }
  }
  datavec_fin(ctx, dv);
  datavec_fin(ctx, rdv);
  return ctx->rc;
}

static void
fake_map(grn_ctx *ctx, grn_io *io, grn_io_win *iw, void *addr, uint32_t seg, uint32_t size)
{
  iw->ctx = ctx;
  iw->diff = 0;
  iw->io = io;
  iw->mode = GRN_IO_WRONLY;
  iw->segment = ((seg) >> GRN_II_N_CHUNK_VARIATION);
  iw->offset = (((seg) & ((1 << GRN_II_N_CHUNK_VARIATION) - 1)) << GRN_II_W_LEAST_CHUNK);
  iw->size = size;
  iw->cached = 0;
  iw->addr = addr;
}

static grn_rc
buffer_flush(grn_ctx *ctx, grn_ii *ii, uint32_t lseg, grn_hash *h)
{
  grn_io_win sw, dw;
  buffer *sb, *db = NULL;
  uint32_t ds, pseg, scn, dcn = 0;
  if (grn_ii_get_buffer_pseg_inline(ii, lseg) == GRN_II_PSEG_NOT_ASSIGNED) {
    GRN_DEFINE_NAME(ii);
    CRIT(GRN_FILE_CORRUPT,
         "[ii][buffer][flush] invalid segment: "
         "<%.*s>: "
         "request:<%u>, max:<%u>",
         name_size, name,
         lseg, ii->seg->header->max_segment);
    return ctx->rc;
  }
  if ((ds = segment_get(ctx, ii)) == ii->seg->header->max_segment) {
    GRN_DEFINE_NAME(ii);
    MERR("[ii][buffer][flush] segment is full: "
         "<%.*s>: "
         "request:<%u>, max:<%u>",
         name_size, name,
         lseg, ii->seg->header->max_segment);
    return ctx->rc;
  }
  pseg = buffer_open(ctx, ii, grn_ii_pos_pack(ii, lseg, 0), NULL, &sb);
  if (pseg == GRN_II_PSEG_NOT_ASSIGNED) {
    GRN_DEFINE_NAME(ii);
    MERR("[ii][buffer][flush] failed to open buffer: "
         "<%.*s>: "
         "segment:<%u>, position:<%u>, max:<%u>",
         name_size, name,
         lseg,
         grn_ii_pos_pack(ii, lseg, 0),
         ii->seg->header->max_segment);
    return ctx->rc;
  }
  {
    db = grn_io_seg_ref(ctx, ii->seg, ds);
    if (db) {
      const uint8_t *sc = NULL;
      if ((scn = sb->header.chunk) == GRN_II_PSEG_NOT_ASSIGNED ||
          (sc = WIN_MAP(ctx, ii->chunk, &sw, scn, 0,
                        sb->header.chunk_size, GRN_IO_RDONLY))) {
        uint16_t n = sb->header.nterms;
        memset(db, 0, S_SEGMENT);
        grn_memcpy(db->terms, sb->terms, n * sizeof(buffer_term));
        db->header.nterms = n;
        uint8_t *dc = NULL;
        grn_merging_data merging_data;
        grn_merging_data_init(ctx, &merging_data, ii);
        buffer_merge(ctx, ii, lseg, h, sb, sc, db, &dc, &merging_data);
        if (ctx->rc == GRN_SUCCESS) {
          const uint32_t actual_chunk_size = db->header.chunk_size;
          bool need_chunk_free = true;
          if (actual_chunk_size > 0) {
            chunk_new(ctx, ii, &dcn, actual_chunk_size);
            if (ctx->rc == GRN_SUCCESS) {
              need_chunk_free = true;
            }
          }
          if (ctx->rc == GRN_SUCCESS) {
            grn_rc rc;
            db->header.chunk =
              (actual_chunk_size > 0) ? dcn : GRN_II_PSEG_NOT_ASSIGNED;
            fake_map(ctx, ii->chunk, &dw, dc, dcn, actual_chunk_size);
            rc = grn_io_win_unmap(ctx, &dw);
            if (rc == GRN_SUCCESS) {
              dc = NULL;
              buffer_segment_update(ii, lseg, ds);
              ii->header.common->total_chunk_size += actual_chunk_size;
              need_chunk_free = false;
              merging_data.succeeded = true;
              if (scn != GRN_II_PSEG_NOT_ASSIGNED) {
                chunk_free(ctx, ii, scn, sb->header.chunk_size);
                ii->header.common->total_chunk_size -= sb->header.chunk_size;
              }
            } else {
              GRN_DEFINE_NAME(ii);
              ERR(rc,
                  "[ii][buffer][flush] failed to unmap a destination chunk: "
                  "<%.*s> : "
                  "segment:<%u>, destination-segment:<%u>, actual-size:<%u>",
                  name_size, name,
                  lseg,
                  dcn,
                  actual_chunk_size);
            }
          }
          if (need_chunk_free) {
            chunk_free(ctx, ii, dcn, actual_chunk_size);
          }
          if (dc) {
            GRN_FREE(dc);
          }
        }
        grn_merging_data_fin(ctx, &merging_data);
        if (scn != GRN_II_PSEG_NOT_ASSIGNED) { grn_io_win_unmap(ctx, &sw); }
      } else {
        GRN_DEFINE_NAME(ii);
        MERR("[ii][buffer][flush] failed to map a source chunk: "
             "<%.*s>: "
             "segment:<%u>, source-segment:<%u>, chunk-size:<%u>",
             name_size, name,
             lseg,
             scn,
             sb->header.chunk_size);
      }
      grn_io_seg_unref(ctx, ii->seg, ds);
    } else {
      GRN_DEFINE_NAME(ii);
      MERR("[ii][buffer][flush] failed to allocate a destination segment: "
           "<%.*s>: "
           "segment:<%u>, destination-segment:<%u>",
           name_size, name,
           lseg,
           ds);
    }
    buffer_close(ctx, ii, pseg);
  }
  return ctx->rc;
}

void
grn_ii_buffer_check(grn_ctx *ctx, grn_ii *ii, uint32_t lseg)
{
  grn_io_win sw;
  buffer *sb;
  uint8_t *sc = NULL;
  uint32_t pseg, scn, nterms_with_corrupt_chunk = 0, nterm_with_chunk = 0;
  uint32_t ndeleted_terms_with_value = 0;
  buffer_term *bt;
  datavec rdv[MAX_N_ELEMENTS + 1];
  uint16_t n;
  int nterms_void = 0;
  int size_in_buffer = 0;
  grn_obj buf;
  size_t lower_bound;
  int64_t nloops = 0, nviolations = 0;
  if (grn_ii_get_buffer_pseg_inline(ii, lseg) == GRN_II_PSEG_NOT_ASSIGNED) {
    GRN_OUTPUT_BOOL(GRN_FALSE);
    return;
  }
  pseg = buffer_open(ctx, ii, grn_ii_pos_pack(ii, lseg, 0), NULL, &sb);
  if (pseg == GRN_II_PSEG_NOT_ASSIGNED) {
    GRN_OUTPUT_BOOL(GRN_FALSE);
    return;
  }
  lower_bound =
    (sb->header.buffer_free + sizeof(buffer_term) * sb->header.nterms)
    / sizeof(buffer_rec);
  datavec_init(ctx, rdv, ii->n_elements, 0, 0);
  if ((ii->header.common->flags & GRN_OBJ_WITH_POSITION)) {
    rdv[ii->n_elements - 1].flags = ODD;
  }
  GRN_OUTPUT_MAP_OPEN("BUFFER", -1);
  GRN_OUTPUT_CSTR("buffer id");
  GRN_OUTPUT_INT64(lseg);
  if ((scn = sb->header.chunk) == GRN_II_PSEG_NOT_ASSIGNED) {
    GRN_OUTPUT_CSTR("void chunk size");
    GRN_OUTPUT_INT64(sb->header.chunk_size);
  } else {
    if ((sc = WIN_MAP(ctx, ii->chunk, &sw, scn, 0, sb->header.chunk_size,
                      GRN_IO_RDONLY))) {
      GRN_OUTPUT_CSTR("chunk size");
      GRN_OUTPUT_INT64(sb->header.chunk_size);
    } else {
      GRN_OUTPUT_CSTR("unmappable chunk size");
      GRN_OUTPUT_INT64(sb->header.chunk_size);
    }
  }
  GRN_OUTPUT_CSTR("buffer term");
  GRN_OUTPUT_ARRAY_OPEN("TERMS", sb->header.nterms);

  GRN_OBJ_INIT(&buf, GRN_BULK, 0, ii->lexicon->header.domain);
  for (bt = sb->terms, n = sb->header.nterms; n; n--, bt++) {
    grn_id tid, tid_;
    char key[GRN_TABLE_MAX_KEY_SIZE];
    int key_size;
    uint32_t nchunks = 0;
    chunk_info *cinfo = NULL;
    grn_id crid = GRN_ID_NIL;
    merger_data data = {0};
    merger_chunk_data *chunk_data = &(data.source.chunk);

    if (!bt->tid && !bt->pos_in_buffer && !bt->size_in_buffer) {
      nterms_void++;
      continue;
    }
    GRN_OUTPUT_ARRAY_OPEN("TERM", -1);
    tid = (bt->tid & GRN_ID_MAX);
    key_size = grn_table_get_key(ctx, ii->lexicon, tid, key,
                                 GRN_TABLE_MAX_KEY_SIZE);
    tid_ = grn_table_get(ctx, ii->lexicon, key, key_size);
    GRN_TEXT_SET(ctx, &buf, key, key_size);
    GRN_OUTPUT_OBJ(&buf, NULL);
    GRN_OUTPUT_INT64(bt->tid);
    GRN_OUTPUT_INT64(tid_);

    size_in_buffer += bt->size_in_buffer;
    if (tid != tid_ && (bt->size_in_buffer || bt->size_in_chunk)) {
      ndeleted_terms_with_value++;
    }
    GRN_OUTPUT_INT64(bt->size_in_buffer);
    GRN_OUTPUT_INT64(bt->size_in_chunk);

    data.ii = ii;
    data.term_id = bt->tid;
    data.source.buffer.buffer = sb;
    data.source.buffer.next_position = bt->pos_in_buffer;
    chunk_data->data_start = sc;
    merger_get_next_buffer(ctx, &data);
    if (sc && bt->size_in_chunk) {
      size_t size = S_SEGMENT * ii->n_elements;
      chunk_data->data = chunk_data->data_start + bt->pos_in_chunk;
      chunk_data->data_end = chunk_data->data + bt->size_in_chunk;
      if ((bt->tid & CHUNK_SPLIT)) {
        uint32_t i;
        GRN_B_DEC(nchunks, chunk_data->data);
        if (!(cinfo = GRN_MALLOCN(chunk_info, nchunks + 1))) {
          datavec_fin(ctx, rdv);
          GRN_OBJ_FIN(ctx, &buf);
          return;
        }
        for (i = 0; i < nchunks; i++) {
          GRN_B_DEC(cinfo[i].segno, chunk_data->data);
          GRN_B_DEC(cinfo[i].size, chunk_data->data);
          GRN_B_DEC(cinfo[i].dgap, chunk_data->data);
          crid += cinfo[i].dgap;
        }
      }
      if (chunk_data->data_end > chunk_data->data) {
        size += grn_p_decv(ctx,
                           ii,
                           crid,
                           chunk_data->data,
                           chunk_data->data_end - chunk_data->data,
                           rdv,
                           ii->n_elements);
        merger_init_chunk_data(ctx, &data, rdv);
        GRN_OUTPUT_INT64(chunk_data->n_documents);
        GRN_OUTPUT_INT64(chunk_data->position_gaps_end -
                         chunk_data->position_gaps);
        {
          int j = 0;
          j++;
          if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
            j++;
          }
          if (chunk_data->n_documents != rdv[j].data_size) {
            nterms_with_corrupt_chunk++;
          }
          j++;
          if ((ii->header.common->flags & GRN_OBJ_WITH_WEIGHT)) {
            j++;
          }
        }
        nterm_with_chunk++;
      }
    }
    {
      uint16_t pos;
      grn_id rid, sid, rid_ = 0, sid_ = 0;
      uint8_t *p;
      buffer_rec *r;
      for (pos = bt->pos_in_buffer; pos; pos = r->step) {
        if (pos < lower_bound) {
          nviolations++;
        }
        r = BUFFER_REC_AT(sb, pos);
        p = GRN_NEXT_ADDR(r);
        GRN_B_DEC(rid, p);
        if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
          GRN_B_DEC(sid, p);
        } else {
          sid = 1;
        }
        if (rid < rid_ || (rid == rid_ && sid < sid_)) {
          nloops++;
        }
        rid_ = rid;
        sid_ = sid;
      }
    }
    GRN_OUTPUT_ARRAY_CLOSE();
    if (cinfo) { GRN_FREE(cinfo); }
  }
  GRN_OBJ_FIN(ctx, &buf);

  GRN_OUTPUT_ARRAY_CLOSE();
  GRN_OUTPUT_CSTR("buffer free");
  GRN_OUTPUT_INT64(sb->header.buffer_free);
  GRN_OUTPUT_CSTR("size in buffer");
  GRN_OUTPUT_INT64(size_in_buffer);
  GRN_OUTPUT_CSTR("nterms");
  GRN_OUTPUT_INT64(sb->header.nterms);
  if (nterms_void != sb->header.nterms_void) {
    GRN_OUTPUT_CSTR("nterms void gap");
    GRN_OUTPUT_INT64(nterms_void - sb->header.nterms_void);
  }
  GRN_OUTPUT_CSTR("nterms with chunk");
  GRN_OUTPUT_INT64(nterm_with_chunk);
  if (nterms_with_corrupt_chunk) {
    GRN_OUTPUT_CSTR("nterms with corrupt chunk");
    GRN_OUTPUT_INT64(nterms_with_corrupt_chunk);
  }
  if (ndeleted_terms_with_value) {
    GRN_OUTPUT_CSTR("number of deleted terms with value");
    GRN_OUTPUT_INT64(ndeleted_terms_with_value);
  }
  if (nloops) {
    GRN_OUTPUT_CSTR("number of loops");
    GRN_OUTPUT_INT64(nloops);
  }
  if (nviolations) {
    GRN_OUTPUT_CSTR("number of violations");
    GRN_OUTPUT_INT64(nviolations);
  }
  GRN_OUTPUT_MAP_CLOSE();
  datavec_fin(ctx, rdv);
  if (sc) { grn_io_win_unmap(ctx, &sw); }
  buffer_close(ctx, ii, pseg);
}

typedef struct {
  buffer_term *bt;
  const char *key;
  uint32_t key_size;
} term_sort;

static int
term_compar(const void *t1, const void *t2)
{
  int r;
  const term_sort *x = (term_sort *)t1, *y = (term_sort *)t2;
  if (x->key_size > y->key_size) {
    r = memcmp(x->key, y->key, y->key_size);
    return r ? r : (int)(x->key_size - y->key_size);
  } else {
    r = memcmp(x->key, y->key, x->key_size);
    return r ? r : (int)(x->key_size - y->key_size);
  }
}

static grn_rc
term_split(grn_ctx *ctx, grn_obj *lexicon, buffer *sb, buffer *db0, buffer *db1)
{
  uint16_t i, n, *nt;
  buffer_term *bt;
  uint32_t s, th = (sb->header.chunk_size + sb->header.nterms) >> 1;
  term_sort *ts = GRN_MALLOC(sb->header.nterms * sizeof(term_sort));
  if (!ts) { return GRN_NO_MEMORY_AVAILABLE; }
  for (i = 0, n = sb->header.nterms, bt = sb->terms; n; bt++, n--) {
    if (bt->tid) {
      grn_id tid = bt->tid & GRN_ID_MAX;
      ts[i].key = _grn_table_key(ctx, lexicon, tid, &ts[i].key_size);
      ts[i].bt = bt;
      i++;
    }
  }
  qsort(ts, i, sizeof(term_sort), term_compar);
  memset(db0, 0, S_SEGMENT);
  bt = db0->terms;
  nt = &db0->header.nterms;
  for (s = 0; n + 1 < i && s <= th; n++, bt++) {
    grn_memcpy(bt, ts[n].bt, sizeof(buffer_term));
    (*nt)++;
    s += ts[n].bt->size_in_chunk + 1;
  }
  memset(db1, 0, S_SEGMENT);
  bt = db1->terms;
  nt = &db1->header.nterms;
  for (; n < i; n++, bt++) {
    grn_memcpy(bt, ts[n].bt, sizeof(buffer_term));
    (*nt)++;
  }
  GRN_FREE(ts);
  GRN_LOG(ctx, GRN_LOG_DEBUG, "d0=%d d1=%d",
          db0->header.nterms, db1->header.nterms);
  return GRN_SUCCESS;
}

static void
array_update(grn_ctx *ctx, grn_ii *ii, uint32_t dls, buffer *db)
{
  uint16_t n;
  buffer_term *bt;
  uint32_t loffset = POS_LOFFSET_HEADER;
  uint32_t *a;
  for (n = db->header.nterms, bt = db->terms; n; n--, bt++) {
    if (bt->tid) {
      grn_id tid = bt->tid & GRN_ID_MAX;
      if ((a = array_at(ctx, ii, tid))) {
        a[0] = grn_ii_pos_pack(ii, dls, loffset);
        array_unref(ctx, ii, tid);
      } else {
        GRN_LOG(ctx, GRN_LOG_WARNING, "array_at failed (%d)", tid);
      }
    }
    loffset += POS_LOFFSET_HEADER;
  }
}

static grn_rc
buffer_split(grn_ctx *ctx, grn_ii *ii, uint32_t lseg, grn_hash *h)
{
  grn_io_win sw, dw0, dw1;
  buffer *sb, *db0 = NULL, *db1 = NULL;
  uint32_t dps0 = 0, dps1 = 0, dls0 = 0, dls1 = 0, sps, scn, dcn0 = 0, dcn1 = 0;
  if (grn_ii_get_buffer_pseg_inline(ii, lseg) == GRN_II_PSEG_NOT_ASSIGNED) {
    GRN_DEFINE_NAME(ii);
    CRIT(GRN_FILE_CORRUPT,
         "[ii][buffer][split] invalid segment: "
         "<%.*s> :"
         "request:<%u>, max:<%u>",
         name_size, name,
         lseg, ii->seg->header->max_segment);
    return ctx->rc;
  }
  buffer_segment_reserve(ctx, ii, &dls0, &dps0, &dls1, &dps1);
  if (ctx->rc != GRN_SUCCESS) {
    GRN_DEFINE_NAME(ii);
    ERR(ctx->rc,
        "[ii][buffer][split] failed to reserve buffer segments: "
        "<%.*s> :"
        "request:<%u>, max:<%u>",
        name_size, name,
        lseg, ii->seg->header->max_segment);
    return ctx->rc;
  }
  sps = buffer_open(ctx, ii, grn_ii_pos_pack(ii, lseg, 0), NULL, &sb);
  if (sps == GRN_II_PSEG_NOT_ASSIGNED) {
    GRN_DEFINE_NAME(ii);
    MERR("[ii][buffer][split] failed to open buffer: "
         "<%.*s> :"
         "segment:<%u>, position:<%u>, max-segment:<%u>",
         name_size, name,
         lseg,
         grn_ii_pos_pack(ii, lseg, 0),
         ii->seg->header->max_segment);
  } else {
    db0 = grn_io_seg_ref(ctx, ii->seg, dps0);
    if (db0) {
      db1 = grn_io_seg_ref(ctx, ii->seg, dps1);
      if (db1) {
        const uint8_t *sc = NULL;
        if ((scn = sb->header.chunk) == GRN_II_PSEG_NOT_ASSIGNED ||
            (sc = WIN_MAP(ctx, ii->chunk, &sw, scn, 0,
                          sb->header.chunk_size, GRN_IO_RDONLY))) {
          term_split(ctx, ii->lexicon, sb, db0, db1);
          uint8_t *dc0 = NULL;
          grn_merging_data merging_data;
          grn_merging_data_init(ctx, &merging_data, ii);
          buffer_merge(ctx, ii, lseg, h, sb, sc, db0, &dc0, &merging_data);
          if (ctx->rc == GRN_SUCCESS) {
            const uint32_t actual_db0_chunk_size = db0->header.chunk_size;
            bool need_db0_chunk_free = false;
            if (actual_db0_chunk_size > 0) {
              chunk_new(ctx, ii, &dcn0, actual_db0_chunk_size);
              if (ctx->rc == GRN_SUCCESS) {
                need_db0_chunk_free = true;
              }
            }
            if (ctx->rc == GRN_SUCCESS) {
              grn_rc rc;
              db0->header.chunk =
                actual_db0_chunk_size ? dcn0 : GRN_II_PSEG_NOT_ASSIGNED;
              fake_map(ctx, ii->chunk, &dw0, dc0, dcn0, actual_db0_chunk_size);
              rc = grn_io_win_unmap(ctx, &dw0);
              if (rc == GRN_SUCCESS) {
                dc0 = NULL;
                uint8_t *dc1 = NULL;
                buffer_merge(ctx, ii, lseg, h, sb, sc, db1, &dc1, &merging_data);
                if (ctx->rc == GRN_SUCCESS) {
                  const uint32_t actual_db1_chunk_size = db1->header.chunk_size;
                  bool need_db1_chunk_free = false;
                  if (actual_db1_chunk_size > 0) {
                    chunk_new(ctx, ii, &dcn1, actual_db1_chunk_size);
                    if (ctx->rc == GRN_SUCCESS) {
                      need_db1_chunk_free = true;
                    }
                  }
                  if (ctx->rc == GRN_SUCCESS) {
                    fake_map(ctx, ii->chunk, &dw1, dc1, dcn1,
                             actual_db1_chunk_size);
                    rc = grn_io_win_unmap(ctx, &dw1);
                    if (rc == GRN_SUCCESS) {
                      dc1 = NULL;
                      db1->header.chunk =
                        (actual_db1_chunk_size > 0) ?
                        dcn1 :
                        GRN_II_PSEG_NOT_ASSIGNED;
                      buffer_segment_update(ii, dls0, dps0);
                      buffer_segment_update(ii, dls1, dps1);
                      array_update(ctx, ii, dls0, db0);
                      array_update(ctx, ii, dls1, db1);
                      buffer_segment_clear(ii, lseg);
                      ii->header.common->total_chunk_size +=
                        actual_db0_chunk_size +
                        actual_db1_chunk_size;
                      need_db0_chunk_free = false;
                      need_db1_chunk_free = false;
                      merging_data.succeeded = true;
                      if (scn != GRN_II_PSEG_NOT_ASSIGNED) {
                        chunk_free(ctx, ii, scn, sb->header.chunk_size);
                        ii->header.common->total_chunk_size -=
                          sb->header.chunk_size;
                      }
                    } else {
                      GRN_DEFINE_NAME(ii);
                      ERR(rc,
                          "[ii][buffer][merge] "
                          "failed to unmap a destination chunk2: "
                          "<%.*s>: "
                          "segment:<%u>, "
                          "destination-chunk1:<%u>, "
                          "destination-chunk2:<%u>, "
                          "actual-size1:<%u>, "
                          "actual-size2:<%u>",
                          name_size, name,
                          lseg,
                          dcn0,
                          dcn1,
                          actual_db0_chunk_size,
                          actual_db1_chunk_size);
                    }
                  }
                  if (need_db1_chunk_free) {
                    chunk_free(ctx, ii, dcn1, actual_db1_chunk_size);
                  }
                  if (dc1) {
                    GRN_FREE(dc1);
                  }
                }
              } else {
                GRN_DEFINE_NAME(ii);
                ERR(rc,
                    "[ii][buffer][merge] "
                    "failed to unmap a destination chunk1: "
                    "<%.*s> :"
                    "segment:<%u>, "
                    "destination-chunk1:<%u>, "
                    "actual-size1:<%u>",
                    name_size, name,
                    lseg,
                    dcn0,
                    actual_db0_chunk_size);
              }
            }
            if (need_db0_chunk_free) {
              chunk_free(ctx, ii, dcn0, actual_db0_chunk_size);
            }
            if (dc0) {
              GRN_FREE(dc0);
            }
          }
          grn_merging_data_fin(ctx, &merging_data);
          if (scn != GRN_II_PSEG_NOT_ASSIGNED) {
            grn_io_win_unmap(ctx, &sw);
          }
        } else {
          GRN_DEFINE_NAME(ii);
          MERR("[ii][buffer][split] failed to map a source chunk: "
               "<%.*s> :"
               "segment:<%u>, "
               "source-segment:<%u>, "
               "chunk-size:<%u>",
               name_size, name,
               lseg,
               scn,
               sb->header.chunk_size);
        }
        grn_io_seg_unref(ctx, ii->seg, dps1);
      } else {
        GRN_DEFINE_NAME(ii);
        MERR("[ii][buffer][split] failed to allocate a destination segment2: "
             "<%.*s>: "
             "segment:<%u>, "
             "destination-segment1:<%u>, "
             "destination-segment2:<%u>",
             name_size, name,
             lseg,
             dps0,
             dps1);
      }
      grn_io_seg_unref(ctx, ii->seg, dps0);
    } else {
      GRN_DEFINE_NAME(ii);
      MERR("[ii][buffer][split] failed to allocate a destination segment1: "
           "<%.*s>: "
           "segment:<%u>, "
           "destination-segment1:<%u>, "
           "destination-segment2:<%u>",
           name_size, name,
           lseg,
           dps0,
           dps1);
    }
    buffer_close(ctx, ii, sps);
  }
  return ctx->rc;
}

#define SCALE_FACTOR 2048
#define MAX_NTERMS   8192
#define SPLIT_COND(ii, buffer)\
  ((buffer)->header.nterms > 1024 ||\
   ((buffer)->header.nterms > 1 &&\
    (buffer)->header.chunk_size * 100 > (ii)->header.common->total_chunk_size))

grn_inline static void
buffer_new_find_segment(grn_ctx *ctx,
                        grn_ii *ii,
                        int size,
                        grn_id tid,
                        grn_hash *h,
                        buffer **b,
                        uint32_t *lseg,
                        uint32_t *pseg)
{
  uint32_t *a;

  a = array_at(ctx, ii, tid);
  if (!a) {
    return;
  }

  for (;;) {
    uint32_t pos = a[0];
    if (!pos || POS_IS_EMBED(pos)) { break; }
    *pseg = buffer_open(ctx, ii, pos, NULL, b);
    if (*pseg == GRN_II_PSEG_NOT_ASSIGNED) { break; }
    if ((*b)->header.buffer_free >= size + sizeof(buffer_term)) {
      *lseg = grn_ii_pos_lseg(ii, pos);
      break;
    }
    buffer_close(ctx, ii, *pseg);
    if (SPLIT_COND(ii, (*b))) {
      /* ((S_SEGMENT - sizeof(buffer_header) + ii->header.common->bmax -
         (*b)->header.nterms * sizeof(buffer_term)) * 4 <
         (*b)->header.chunk_size) */
      GRN_LOG(ctx, GRN_LOG_DEBUG,
              "nterms=%d chunk=%d total=%" GRN_FMT_INT64U,
              (*b)->header.nterms,
              (*b)->header.chunk_size,
              ii->header.common->total_chunk_size >> 10);
      if (buffer_split(ctx, ii, grn_ii_pos_lseg(ii, pos), h)) { break; }
    } else {
      if (S_SEGMENT - sizeof(buffer_header)
          - (*b)->header.nterms * sizeof(buffer_term)
          < size + sizeof(buffer_term)) {
        break;
      }
      if (buffer_flush(ctx, ii, grn_ii_pos_lseg(ii, pos), h)) { break; }
    }
  }

  array_unref(ctx, ii, tid);
}

grn_inline static void
buffer_new_lexicon_pat(grn_ctx *ctx,
                       grn_ii *ii,
                       int size,
                       grn_id id,
                       grn_hash *h,
                       buffer **b,
                       uint32_t *lseg,
                       uint32_t *pseg)
{
  grn_pat_cursor *cursor;
  char key[GRN_TABLE_MAX_KEY_SIZE];
  int key_size;

  key_size = grn_table_get_key(ctx, ii->lexicon, id, key,
                               GRN_TABLE_MAX_KEY_SIZE);
  if (ii->lexicon->header.flags & GRN_OBJ_KEY_VAR_SIZE) {
    grn_obj *tokenizer = NULL;

    grn_table_get_info(ctx, ii->lexicon, NULL, NULL, &tokenizer, NULL, NULL);
    if (tokenizer) {
      /* For natural language */
      cursor = grn_pat_cursor_open(ctx,
                                   (grn_pat *)(ii->lexicon),
                                   key,
                                   key_size,
                                   NULL,
                                   0,
                                   0,
                                   -1,
                                   GRN_CURSOR_ASCENDING|GRN_CURSOR_GT);
      if (cursor) {
        grn_id tid;
        while (ctx->rc == GRN_SUCCESS &&
               *lseg == GRN_II_PSEG_NOT_ASSIGNED &&
               (tid = grn_pat_cursor_next(ctx, cursor))) {
          buffer_new_find_segment(ctx, ii, size, tid, h, b, lseg, pseg);
        }
        grn_pat_cursor_close(ctx, cursor);
      }
    } else {
      /* For binary data or text data */
      grn_bool is_binary_data;
      int target_key_size = key_size;
      int reduced_key_size = 0;

      is_binary_data = (ctx->encoding == GRN_ENC_NONE);

      while (*lseg == GRN_II_PSEG_NOT_ASSIGNED && target_key_size > 0) {
        grn_id tid;

        cursor = grn_pat_cursor_open(ctx,
                                     (grn_pat *)(ii->lexicon),
                                     key, target_key_size,
                                     NULL, 0, 0, -1,
                                     GRN_CURSOR_PREFIX);
        if (!cursor) {
          break;
        }

        if (reduced_key_size == 0) {
          while (ctx->rc == GRN_SUCCESS &&
                 *lseg == GRN_II_PSEG_NOT_ASSIGNED &&
                 (tid = grn_pat_cursor_next(ctx, cursor))) {
            buffer_new_find_segment(ctx, ii, size, tid, h, b, lseg, pseg);
          }
        } else {
          while (ctx->rc == GRN_SUCCESS &&
                 *lseg == GRN_II_PSEG_NOT_ASSIGNED &&
                 (tid = grn_pat_cursor_next(ctx, cursor))) {
            void *current_key;
            int current_key_size;

            current_key_size = grn_pat_cursor_get_key(ctx, cursor, &current_key);
            if (memcmp(((char *)current_key) + target_key_size,
                       key + target_key_size,
                       reduced_key_size) == 0) {
              continue;
            }
            buffer_new_find_segment(ctx, ii, size, tid, h, b, lseg, pseg);
          }
        }
        grn_pat_cursor_close(ctx, cursor);

        if (reduced_key_size == 0) {
          reduced_key_size = 1;
        } else {
          if (is_binary_data) {
            reduced_key_size *= 2;
          }
        }
        target_key_size -= reduced_key_size;
      }
    }
  } else {
    /* For other data */
    cursor = grn_pat_cursor_open(ctx,
                                 (grn_pat *)(ii->lexicon),
                                 NULL, 0, key, key_size, 0, -1,
                                 GRN_CURSOR_PREFIX);
    if (cursor) {
      grn_id tid;
      while (ctx->rc == GRN_SUCCESS &&
             *lseg == GRN_II_PSEG_NOT_ASSIGNED &&
             (tid = grn_pat_cursor_next(ctx, cursor))) {
        buffer_new_find_segment(ctx, ii, size, tid, h, b, lseg, pseg);
      }
      grn_pat_cursor_close(ctx, cursor);
    }
  }
}

grn_inline static void
buffer_new_lexicon_other(grn_ctx *ctx,
                         grn_ii *ii,
                         int size,
                         grn_id id,
                         grn_hash *h,
                         buffer **b,
                         uint32_t *lseg,
                         uint32_t *pseg)
{
  GRN_TABLE_EACH_BEGIN(ctx, ii->lexicon, cursor, tid) {
    if (ctx->rc != GRN_SUCCESS || *lseg != GRN_II_PSEG_NOT_ASSIGNED) {
      break;
    }
    buffer_new_find_segment(ctx, ii, size, tid, h, b, lseg, pseg);
  } GRN_TABLE_EACH_END(ctx, cursor);
}


grn_inline static uint32_t
buffer_new(grn_ctx *ctx, grn_ii *ii, int size, uint32_t *pos,
           buffer_term **bt, buffer_rec **br, buffer **bp, grn_id id, grn_hash *h)
{
  buffer *b = NULL;
  uint16_t offset;
  uint32_t lseg = GRN_II_PSEG_NOT_ASSIGNED, pseg = GRN_II_PSEG_NOT_ASSIGNED;
  if (S_SEGMENT - sizeof(buffer_header) < size + sizeof(buffer_term)) {
    GRN_DEFINE_NAME(ii);
    MERR("[ii][buffer][new] requested size is too large: "
         "<%.*s> :"
         "requested:<%" GRN_FMT_SIZE ">, max:<%" GRN_FMT_SIZE ">",
         name_size, name,
         (size_t)(size + sizeof(buffer_term)),
         (size_t)(S_SEGMENT - sizeof(buffer_header)));
    return GRN_II_PSEG_NOT_ASSIGNED;
  }
  if (ii->lexicon->header.type == GRN_TABLE_PAT_KEY) {
    buffer_new_lexicon_pat(ctx, ii, size, id, h, &b, &lseg, &pseg);
  } else {
    buffer_new_lexicon_other(ctx, ii, size, id, h, &b, &lseg, &pseg);
  }
  if (lseg == GRN_II_PSEG_NOT_ASSIGNED) {
    if (buffer_segment_new(ctx, ii, &lseg) ||
        (pseg = buffer_open(ctx,
                            ii,
                            grn_ii_pos_pack(ii, lseg, 0),
                            NULL,
                            &b)) == GRN_II_PSEG_NOT_ASSIGNED) {
      return GRN_II_PSEG_NOT_ASSIGNED;
    }
    memset(b, 0, S_SEGMENT);
    b->header.buffer_free = S_SEGMENT - sizeof(buffer_header);
    b->header.chunk = GRN_II_PSEG_NOT_ASSIGNED;
  }
  if (b->header.nterms_void) {
    for (offset = 0; offset < b->header.nterms; offset++) {
      if (!b->terms[offset].tid) { break; }
    }
    if (offset == b->header.nterms) {
      GRN_LOG(ctx, GRN_LOG_DEBUG, "inconsistent buffer(%d)", lseg);
      b->header.nterms_void = 0;
      b->header.nterms++;
      b->header.buffer_free -= size + sizeof(buffer_term);
    } else {
      b->header.nterms_void--;
      b->header.buffer_free -= size;
    }
  } else {
    offset = b->header.nterms++;
    b->header.buffer_free -= size + sizeof(buffer_term);
  }
  *pos = grn_ii_pos_pack(ii,
                         lseg,
                         POS_LOFFSET_HEADER + POS_LOFFSET_TERM * offset);
  *bt = &b->terms[offset];
  *br = (buffer_rec *)(((byte *)&b->terms[b->header.nterms]) + b->header.buffer_free);
  *bp = b;
  return pseg;
}

/* ii */

static grn_ii *
_grn_ii_create(grn_ctx *ctx, grn_ii *ii, const char *path, grn_obj *lexicon, uint32_t flags)
{
  int i;
  uint32_t header_size;
  uint32_t max_n_segments;
  uint32_t max_n_chunks;
  grn_io *seg, *chunk;
  char path2[PATH_MAX];
  grn_ii_header_common *header;
  grn_table_flags lflags;
  grn_encoding encoding;
  grn_obj *tokenizer;
  /*
  for (i = 0; i < 32; i++) {
    new_histogram[i] = 0;
    free_histogram[i] = 0;
  }
  */
  if (grn_table_get_info(ctx, lexicon, &lflags, &encoding, &tokenizer,
                         NULL, NULL)) {
    return NULL;
  }
  if (path && strlen(path) + 6 >= PATH_MAX) { return NULL; }

  if (!grn_ii_pos_is_available(ctx, flags, "[ii][create]")) {
    return NULL;
  }

  if (flags & GRN_OBJ_INDEX_SMALL) {
    header_size = sizeof(grn_ii_header_normal);
    max_n_segments = grn_ii_max_n_segments_small;
    max_n_chunks = grn_ii_max_n_chunks_small;
  } else if (flags & GRN_OBJ_INDEX_MEDIUM) {
    header_size = sizeof(grn_ii_header_normal);
    max_n_segments = MAX_PSEG_MEDIUM;
    max_n_chunks = GRN_II_MAX_CHUNK_MEDIUM;
  } else if (flags & GRN_OBJ_INDEX_LARGE) {
    header_size = sizeof(grn_ii_header_large);
    max_n_segments = MAX_PSEG_LARGE;
    max_n_chunks = GRN_II_MAX_CHUNK;
  } else {
    header_size = sizeof(grn_ii_header_normal);
    max_n_segments = MAX_PSEG;
    max_n_chunks = GRN_II_MAX_CHUNK;
  }

  seg = grn_io_create(ctx,
                      path,
                      header_size,
                      S_SEGMENT,
                      max_n_segments,
                      GRN_IO_AUTO,
                      GRN_IO_EXPIRE_SEGMENT);
  if (!seg) { return NULL; }
  if (path) {
    grn_strcpy(path2, PATH_MAX, path);
    grn_strcat(path2, PATH_MAX, ".c");
    chunk = grn_io_create(ctx, path2, 0, S_CHUNK, max_n_chunks, GRN_IO_AUTO,
                          GRN_IO_EXPIRE_SEGMENT);
  } else {
    chunk = grn_io_create(ctx, NULL, 0, S_CHUNK, max_n_chunks, GRN_IO_AUTO, 0);
  }
  if (!chunk) {
    grn_io_close(ctx, seg);
    grn_io_remove(ctx, path);
    return NULL;
  }
  header = grn_io_header(seg);
  grn_io_set_type(seg, GRN_COLUMN_INDEX);
  for (i = 0; i < GRN_II_MAX_LSEG; i++) {
    header->ainfo[i] = GRN_II_PSEG_NOT_ASSIGNED;
    header->binfo[i] = GRN_II_PSEG_NOT_ASSIGNED;
  }
  if (flags & GRN_OBJ_INDEX_LARGE) {
    grn_ii_header_large *header_large = (grn_ii_header_large *)header;
    for (i = 0; i < GRN_II_MAX_LSEG_EXTEND; i++) {
      header_large->ainfo_extend[i] = GRN_II_PSEG_NOT_ASSIGNED;
      header_large->binfo_extend[i] = GRN_II_PSEG_NOT_ASSIGNED;
    }
  }
  for (i = 0; i <= GRN_II_N_CHUNK_VARIATION; i++) {
    header->free_chunks[i] = GRN_II_PSEG_NOT_ASSIGNED;
    header->garbages[i] = GRN_II_PSEG_NOT_ASSIGNED;
  }
  header->flags = flags;
  ii->seg = seg;
  ii->chunk = chunk;
  ii->lexicon = grn_ctx_at(ctx, DB_OBJ(lexicon)->id);
  ii->lflags = lflags;
  ii->encoding = encoding;
  ii->header.common = header;
  ii->n_elements = 2;
  if ((flags & GRN_OBJ_WITH_SECTION)) { ii->n_elements++; }
  if ((flags & GRN_OBJ_WITH_WEIGHT)) { ii->n_elements++; }
  if ((flags & GRN_OBJ_WITH_POSITION)) { ii->n_elements++; }
  ii->wal_touched = false;
  return ii;
}

grn_ii *
grn_ii_create(grn_ctx *ctx, const char *path, grn_obj *lexicon, uint32_t flags)
{
  grn_ii *ii = NULL;
  if (!(ii = GRN_CALLOC(sizeof(grn_ii)))) {
    return NULL;
  }
  GRN_DB_OBJ_SET_TYPE(ii, GRN_COLUMN_INDEX);
  if (!_grn_ii_create(ctx, ii, path, lexicon, flags)) {
    GRN_FREE(ii);
    return NULL;
  }
  return ii;
}

grn_rc
grn_ii_remove(grn_ctx *ctx, const char *path)
{
  grn_rc rc;
  char buffer[PATH_MAX];
  if (!path || strlen(path) > PATH_MAX - 4) { return GRN_INVALID_ARGUMENT; }
  grn_rc wal_rc = grn_wal_remove(ctx, path, "[ii]");
  if ((rc = grn_io_remove(ctx, path))) { goto exit; }
  grn_snprintf(buffer, PATH_MAX, PATH_MAX,
               "%s.c", path);
  rc = grn_io_remove(ctx, buffer);
  if (rc == GRN_SUCCESS) {
    rc = wal_rc;
  }
exit :
  return rc;
}

grn_rc
grn_ii_truncate(grn_ctx *ctx, grn_ii *ii)
{
  grn_rc rc;
  const char *io_segpath;
  char *segpath = NULL;
  grn_obj *lexicon;
  uint32_t flags;
  if ((io_segpath = grn_io_path(ii->seg)) && *io_segpath != '\0') {
    if (!(segpath = GRN_STRDUP(io_segpath))) {
      ERR(GRN_NO_MEMORY_AVAILABLE, "cannot duplicate path: <%s>", io_segpath);
      return GRN_NO_MEMORY_AVAILABLE;
    }
  } else {
    segpath = NULL;
  }
  lexicon = ii->lexicon;
  flags = ii->header.common->flags;
  if ((rc = grn_io_close(ctx, ii->seg))) { goto exit; }
  if ((rc = grn_io_close(ctx, ii->chunk))) { goto exit; }
  ii->seg = NULL;
  ii->chunk = NULL;
  if (segpath && (rc = grn_ii_remove(ctx, segpath))) { goto exit; }
  if (!_grn_ii_create(ctx, ii, segpath, lexicon, flags)) {
    rc = GRN_UNKNOWN_ERROR;
    goto exit;
  }
  grn_obj_unref(ctx, lexicon);
exit:
  if (segpath) { GRN_FREE(segpath); }
  return rc;
}

grn_ii *
grn_ii_open(grn_ctx *ctx, const char *path, grn_obj *lexicon)
{
  grn_io *seg, *chunk;
  grn_ii *ii;
  char path2[PATH_MAX];
  grn_ii_header_common *header;
  uint32_t io_type;
  grn_table_flags lflags;
  grn_encoding encoding;
  grn_obj *tokenizer;
  if (grn_table_get_info(ctx, lexicon, &lflags, &encoding, &tokenizer,
                         NULL, NULL)) {
    return NULL;
  }
  if (strlen(path) + 6 >= PATH_MAX) { return NULL; }
  grn_strcpy(path2, PATH_MAX, path);
  grn_strcat(path2, PATH_MAX, ".c");
  seg = grn_io_open(ctx, path, GRN_IO_AUTO);
  if (!seg) { return NULL; }
  chunk = grn_io_open(ctx, path2, GRN_IO_AUTO);
  if (!chunk) {
    grn_io_close(ctx, seg);
    return NULL;
  }
  header = grn_io_header(seg);
  io_type = grn_io_get_type(seg);
  if (io_type != GRN_COLUMN_INDEX) {
    ERR(GRN_INVALID_FORMAT,
        "[column][index] file type must be %#04x: <%#04x>",
        GRN_COLUMN_INDEX, io_type);
    grn_io_close(ctx, seg);
    grn_io_close(ctx, chunk);
    return NULL;
  }
  if (!(ii = GRN_CALLOC(sizeof(grn_ii)))) {
    grn_io_close(ctx, seg);
    grn_io_close(ctx, chunk);
    return NULL;
  }
  GRN_DB_OBJ_SET_TYPE(ii, GRN_COLUMN_INDEX);
  ii->seg = seg;
  ii->chunk = chunk;
  ii->lexicon = grn_ctx_at(ctx, DB_OBJ(lexicon)->id);
  ii->lflags = lflags;
  ii->encoding = encoding;
  ii->header.common = header;
  ii->n_elements = 2;
  if ((header->flags & GRN_OBJ_WITH_SECTION)) { ii->n_elements++; }
  if ((header->flags & GRN_OBJ_WITH_WEIGHT)) { ii->n_elements++; }
  if ((header->flags & GRN_OBJ_WITH_POSITION)) { ii->n_elements++; }
  ii->wal_touched = false;
  return ii;
}

grn_rc
grn_ii_close(grn_ctx *ctx, grn_ii *ii)
{
  grn_rc rc = GRN_SUCCESS;
  if (!ii) { return GRN_INVALID_ARGUMENT; }
  if (ii->seg->path[0] != '\0' &&
      GRN_CTX_GET_WAL_ROLE(ctx) == GRN_WAL_ROLE_PRIMARY) {
    grn_obj_flush(ctx, (grn_obj *)ii);
  }
  {
    grn_rc sub_rc = grn_io_close(ctx, ii->seg);
    if (rc == GRN_SUCCESS) {
      rc = sub_rc;
    }
  }
  {
    grn_rc sub_rc = grn_io_close(ctx, ii->chunk);
    if (rc == GRN_SUCCESS) {
      rc = sub_rc;
    }
  }
  if (grn_enable_reference_count) {
    grn_obj_unlink(ctx, ii->lexicon);
  }
  GRN_FREE(ii);
  /*
  {
    int i;
    for (i = 0; i < 32; i++) {
      GRN_LOG(ctx, GRN_LOG_DEBUG, "new[%d]=%d free[%d]=%d",
              i, new_histogram[i],
              i, free_histogram[i]);
    }
  }
  */
  return rc;
}

grn_rc
grn_ii_info(grn_ctx *ctx, grn_ii *ii, uint64_t *seg_size, uint64_t *chunk_size)
{
  grn_rc rc;

  if (seg_size) {
    if ((rc = grn_io_size(ctx, ii->seg, seg_size))) {
      return rc;
    }
  }

  if (chunk_size) {
    if ((rc = grn_io_size(ctx, ii->chunk, chunk_size))) {
      return rc;
    }
  }

  return GRN_SUCCESS;
}

grn_column_flags
grn_ii_get_flags(grn_ctx *ctx, grn_ii *ii)
{
  if (!ii) {
    return 0;
  }

  return ii->header.common->flags;
}

uint32_t
grn_ii_get_n_elements(grn_ctx *ctx, grn_ii *ii)
{
  if (!ii) {
    return 0;
  }

  return ii->n_elements;
}

void
grn_ii_expire(grn_ctx *ctx, grn_ii *ii)
{
  int64_t threshold = ii->chunk->max_map_seg / 2;
  /*
  grn_io_expire(ctx, ii->seg, 128, 1000000);
  */
  if (0 <= grn_ii_reduce_expire_threshold &&
      grn_ii_reduce_expire_threshold < threshold) {
    threshold = grn_ii_reduce_expire_threshold;
  }
  if (ii->chunk->nmaps > threshold) {
    grn_io_expire(ctx, ii->chunk, 0, 1000000);
  }
}

grn_rc
grn_ii_flush(grn_ctx *ctx, grn_ii *ii)
{
  grn_rc rc;

  rc = grn_io_flush(ctx, ii->seg);
  if (rc == GRN_SUCCESS) {
    rc = grn_io_flush(ctx, ii->chunk);
  }

  if (rc == GRN_SUCCESS) {
    ii->wal_touched = false;
  }

  return rc;
}

size_t
grn_ii_get_disk_usage(grn_ctx *ctx, grn_ii *ii)
{
  size_t usage;

  usage = grn_io_get_disk_usage(ctx, ii->seg);
  usage += grn_io_get_disk_usage(ctx, ii->chunk);

  return usage;
}

void
grn_ii_set_visibility(grn_ctx *ctx, grn_ii *ii, bool is_visible)
{
  if (is_visible) {
    ii->header.common->flags &= ~GRN_OBJ_INVISIBLE;
  } else {
    ii->header.common->flags |= GRN_OBJ_INVISIBLE;
  }
}

#define BIT11_01(x) ((x >> 1) & 0x7ff)
#define BIT31_12(x) (x >> 12)

grn_inline static grn_rc
grn_ii_wal_touch(grn_ctx *ctx, grn_ii *ii, const char *tag)
{
  if (ii->wal_touched) {
    return GRN_SUCCESS;
  }

  if (GRN_CTX_GET_WAL_ROLE(ctx) == GRN_WAL_ROLE_NONE) {
    return GRN_SUCCESS;
  }

  grn_rc rc = grn_wal_touch(ctx, (grn_obj *)ii, false, tag);
  if (rc == GRN_SUCCESS) {
    ii->wal_touched = true;
  }
  return rc;
}

grn_rc
grn_ii_update_one(grn_ctx *ctx, grn_ii *ii, grn_id tid, grn_ii_updspec *u, grn_hash *h)
{
  const char *tag = "[ii][update][one]";
  buffer *b;
  uint8_t *bs;
  buffer_rec *br = NULL;
  buffer_term *bt;
  uint32_t pseg = 0, pos = 0, size, *a;
  if (!tid) { return ctx->rc; }
  if (!u->tf || !u->sid) { return grn_ii_delete_one(ctx, ii, tid, u, h); }
  if (u->sid > ii->header.common->smax) { ii->header.common->smax = u->sid; }
  if (!(a = array_get(ctx, ii, tid))) {
    grn_obj term;
    GRN_DEFINE_NAME(ii);
    GRN_TEXT_INIT(&term, 0);
    grn_ii_get_term(ctx, ii, tid, &term);
    MERR("%s failed to allocate an array: "
         "<%.*s>: "
         "<%.*s>(%u): "
         "(%u:%u)",
         tag,
         name_size, name,
         (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
         tid,
         u->rid, u->sid);
    GRN_OBJ_FIN(ctx, &term);
    return ctx->rc;
  }
  if (!(bs = encode_rec(ctx, ii, u, &size, 0))) {
    grn_obj term;
    GRN_DEFINE_NAME(ii);
    GRN_TEXT_INIT(&term, 0);
    grn_ii_get_term(ctx, ii, tid, &term);
    MERR("%s failed to encode a record: "
         "<%.*s>: "
         "<%.*s>(%u): "
         "(%u:%u)",
         tag,
         name_size, name,
         (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
         tid,
         u->rid, u->sid);
    GRN_OBJ_FIN(ctx, &term);
    goto exit;
  }
  if (grn_ii_wal_touch(ctx, ii, tag) != GRN_SUCCESS) {
    goto exit;
  }
  for (;;) {
    if (a[0]) {
      if (!POS_IS_EMBED(a[0])) {
        pos = a[0];
        if ((pseg = buffer_open(ctx, ii, pos, &bt, &b)) == GRN_II_PSEG_NOT_ASSIGNED) {
          grn_obj term;
          GRN_DEFINE_NAME(ii);
          GRN_TEXT_INIT(&term, 0);
          grn_ii_get_term(ctx, ii, tid, &term);
          MERR("%s failed to allocate a buffer: "
               "<%.*s>: "
               "<%.*s>(%u): "
               "(%u:%u): "
               "segment:<%u>, "
               "free:<%u>, "
               "required:<%u>",
               tag,
               name_size, name,
               (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
               tid,
               u->rid, u->sid,
               pos,
               b->header.buffer_free,
               size);
          GRN_OBJ_FIN(ctx, &term);
          goto exit;
        }
        if (b->header.buffer_free < size) {
          int bfb = b->header.buffer_free;
          GRN_LOG(ctx, GRN_LOG_DEBUG, "flushing a[0]=%d seg=%d(%p) free=%d",
                  a[0], grn_ii_pos_lseg(ii, a[0]), b, b->header.buffer_free);
          buffer_close(ctx, ii, pseg);
          if (SPLIT_COND(ii, b)) {
            /*((S_SEGMENT - sizeof(buffer_header) + ii->header.common->bmax -
               b->header.nterms * sizeof(buffer_term)) * 4 <
               b->header.chunk_size)*/
            GRN_LOG(ctx, GRN_LOG_DEBUG,
                    "nterms=%d chunk=%d total=%" GRN_FMT_INT64U,
                    b->header.nterms,
                    b->header.chunk_size,
                    ii->header.common->total_chunk_size >> 10);
            buffer_split(ctx, ii, grn_ii_pos_lseg(ii, pos), h);
            if (ctx->rc != GRN_SUCCESS) {
              grn_obj term;
              char errbuf[GRN_CTX_MSGSIZE];
              GRN_DEFINE_NAME(ii);
              GRN_TEXT_INIT(&term, 0);
              grn_ii_get_term(ctx, ii, tid, &term);
              grn_strcpy(errbuf, GRN_CTX_MSGSIZE, ctx->errbuf);
              ERR(ctx->rc,
                  "%s failed to split a buffer: "
                  "<%.*s>: "
                  "<%.*s>(%u): "
                  "(%u:%u): "
                  "segment:<%u>, "
                  "free:<%u>, "
                  "required:<%u>, "
                  "%s",
                  tag,
                  name_size, name,
                  (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                  tid,
                  u->rid, u->sid,
                  pos,
                  b->header.buffer_free,
                  size,
                  errbuf);
              GRN_OBJ_FIN(ctx, &term);
              goto exit;
            }
            continue;
          }
          buffer_flush(ctx, ii, grn_ii_pos_lseg(ii, pos), h);
          if (ctx->rc != GRN_SUCCESS) {
            grn_obj term;
            char errbuf[GRN_CTX_MSGSIZE];
            GRN_DEFINE_NAME(ii);
            GRN_TEXT_INIT(&term, 0);
            grn_ii_get_term(ctx, ii, tid, &term);
            grn_strcpy(errbuf, GRN_CTX_MSGSIZE, ctx->errbuf);
            ERR(ctx->rc,
                "%s failed to flush a buffer: "
                "<%.*s>: "
                "<%u>:<%u>:<%u>: "
                "term:<%.*s>, "
                "segment:<%u>, "
                "free:<%u>, "
                "required:<%u>: "
                "%s",
                tag,
                name_size, name,
                u->rid, u->sid, tid,
                (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                pos,
                b->header.buffer_free,
                size,
                errbuf);
            GRN_OBJ_FIN(ctx, &term);
            goto exit;
          }
          if (a[0] != pos) {
            GRN_LOG(ctx, GRN_LOG_DEBUG,
                    "grn_ii_update_one: a[0] changed %d->%d", a[0], pos);
            continue;
          }
          if ((pseg = buffer_open(ctx, ii, pos, &bt, &b)) == GRN_II_PSEG_NOT_ASSIGNED) {
            GRN_LOG(ctx, GRN_LOG_CRIT, "buffer not found a[0]=%d", a[0]);
            {
              grn_obj term;
              GRN_DEFINE_NAME(ii);
              GRN_TEXT_INIT(&term, 0);
              grn_ii_get_term(ctx, ii, tid, &term);
              MERR("%s failed to reallocate a buffer: "
                   "<%.*s>: "
                   "<%.*s>(%u): "
                   "(%u:%u): "
                   "segment:<%u>, "
                   "new-segment:<%u>, "
                   "free:<%u>, "
                   "required:<%u>",
                   tag,
                   name_size, name,
                   (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                   tid,
                   u->rid, u->sid,
                   pos,
                   a[0],
                   b->header.buffer_free,
                   size);
              GRN_OBJ_FIN(ctx, &term);
            }
            goto exit;
          }
          GRN_LOG(ctx, GRN_LOG_DEBUG,
                  "flushed  a[0]=%d seg=%d(%p) free=%d->%d nterms=%d v=%d",
                  a[0], grn_ii_pos_lseg(ii, a[0]), b, bfb, b->header.buffer_free,
                  b->header.nterms, b->header.nterms_void);
          if (b->header.buffer_free < size) {
            grn_obj term;
            GRN_DEFINE_NAME(ii);
            GRN_TEXT_INIT(&term, 0);
            grn_ii_get_term(ctx, ii, tid, &term);
            MERR("%s buffer is full: "
                 "<%.*s>: "
                 "<%.*s>(%u): "
                 "(%u:%u): "
                 "segment:<%u>, "
                 "new-segment:<%u>, "
                 "free:<%u>, "
                 "required:<%u>",
                 tag,
                 name_size, name,
                 (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                 tid,
                 u->rid, u->sid,
                 pos, a[0], b->header.buffer_free, size);
            GRN_OBJ_FIN(ctx, &term);
            buffer_close(ctx, ii, pseg);
            /* todo: direct merge */
            goto exit;
          }
        }
        b->header.buffer_free -= size;
        br = (buffer_rec *)(((byte *)&b->terms[b->header.nterms])
                            + b->header.buffer_free);
      } else {
        grn_ii_updspec u2;
        uint32_t size2 = 0, v = a[0];
        struct _grn_ii_pos pos2;
        pos2.pos = a[1];
        pos2.next = NULL;
        u2.pos = &pos2;
        if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
          u2.rid = POS_RID_SID_EXTRACT_RID(v);
          u2.sid = POS_RID_SID_EXTRACT_SID(v);
        } else {
          u2.rid = POS_RID_EXTRACT(v);
          u2.sid = 1;
        }
        u2.tf = 1;
        u2.weight = 0;
        if (u2.rid != u->rid || u2.sid != u->sid) {
          uint8_t *bs2 = encode_rec(ctx, ii, &u2, &size2, 0);
          if (!bs2) {
            grn_obj term;
            GRN_DEFINE_NAME(ii);
            GRN_TEXT_INIT(&term, 0);
            grn_ii_get_term(ctx, ii, tid, &term);
            MERR("%s failed to encode a record2: "
                 "<%.*s>: "
                 "<%.*s>(%u): "
                 "(%u:%u)",
                 tag,
                 name_size, name,
                 (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                 tid,
                 u2.rid, u2.sid);
            GRN_OBJ_FIN(ctx, &term);
            goto exit;
          }
          pseg = buffer_new(ctx, ii, size + size2, &pos, &bt, &br, &b, tid, h);
          if (pseg == GRN_II_PSEG_NOT_ASSIGNED) {
            GRN_FREE(bs2);
            {
              grn_obj term;
              GRN_DEFINE_NAME(ii);
              GRN_TEXT_INIT(&term, 0);
              grn_ii_get_term(ctx, ii, tid, &term);
              MERR("%s failed to create a buffer2: "
                   "<%.*s>: "
                   "<%.*s>(%u): "
                   "(%u:%u): "
                   "size:<%u>",
                   tag,
                   name_size, name,
                   (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                   tid,
                   u2.rid, u2.sid,
                   size + size2);
              GRN_OBJ_FIN(ctx, &term);
            }
            goto exit;
          }
          bt->tid = tid;
          bt->size_in_chunk = 0;
          bt->pos_in_chunk = 0;
          bt->size_in_buffer = 0;
          bt->pos_in_buffer = 0;
          buffer_put(ctx, ii, b, bt, br, bs2, &u2, size2);
          if (ctx->rc != GRN_SUCCESS) {
            GRN_FREE(bs2);
            buffer_close(ctx, ii, pseg);
            {
              grn_obj term;
              char errbuf[GRN_CTX_MSGSIZE];
              GRN_DEFINE_NAME(ii);
              GRN_TEXT_INIT(&term, 0);
              grn_ii_get_term(ctx, ii, tid, &term);
              grn_strcpy(errbuf, GRN_CTX_MSGSIZE, ctx->errbuf);
              MERR("%s failed to put to buffer: "
                   "<%.*s>: "
                   "<%.*s>(%u): "
                   "(%u:%u): "
                   "%s",
                   tag,
                   name_size, name,
                   (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                   tid,
                   u2.rid, u2.sid,
                   errbuf);
              GRN_OBJ_FIN(ctx, &term);
            }
            goto exit;
          }
          br = (buffer_rec *)(((byte *)br) + size2);
          GRN_FREE(bs2);
        }
      }
    }
    break;
  }
  if (!br) {
    if (u->tf == 1 && u->weight == 0) {
      if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
        if (u->rid < 0x100000 && u->sid < 0x800) {
          a[0] = (u->rid << 12) + (u->sid << 1) + 1;
          a[1] = u->pos->pos;
          goto exit;
        }
      } else {
        a[0] = (u->rid << 1) + 1;
        a[1] = u->pos->pos;
        goto exit;
      }
    }
    pseg = buffer_new(ctx, ii, size, &pos, &bt, &br, &b, tid, h);
    if (pseg == GRN_II_PSEG_NOT_ASSIGNED) {
      grn_obj term;
      GRN_DEFINE_NAME(ii);
      GRN_TEXT_INIT(&term, 0);
      grn_ii_get_term(ctx, ii, tid, &term);
      MERR("%s failed to create a buffer: "
           "<%.*s>: "
           "<%.*s>(%u): "
           "(%u:%u): "
           "size:<%u>",
           tag,
           name_size, name,
           (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
           tid,
           u->rid, u->sid,
           size);
      GRN_OBJ_FIN(ctx, &term);
      goto exit;
    }
    bt->tid = tid;
    bt->size_in_chunk = 0;
    bt->pos_in_chunk = 0;
    bt->size_in_buffer = 0;
    bt->pos_in_buffer = 0;
  }
  buffer_put(ctx, ii, b, bt, br, bs, u, size);
  buffer_close(ctx, ii, pseg);
  if (!a[0] || POS_IS_EMBED(a[0])) { a[0] = pos; }
exit :
  array_unref(ctx, ii, tid);
  if (bs) { GRN_FREE(bs); }
  if (u->tf != u->atf) {
    grn_obj *source_table;
    char source_table_name[GRN_TABLE_MAX_KEY_SIZE];
    int source_table_name_size;

    source_table = grn_ctx_at(ctx, DB_OBJ(ii)->range);
    if (source_table) {
      source_table_name_size = grn_obj_name(ctx,
                                            source_table,
                                            source_table_name,
                                            GRN_TABLE_MAX_KEY_SIZE);
    } else {
      grn_strcpy(source_table_name, GRN_TABLE_MAX_KEY_SIZE, "(null)");
      source_table_name_size = strlen(source_table_name);
    }
    {
      grn_obj term;
      GRN_DEFINE_NAME(ii);
      GRN_TEXT_INIT(&term, 0);
      grn_ii_get_term(ctx, ii, tid, &term);
      GRN_LOG(ctx, GRN_LOG_WARNING,
              "%s too many postings: "
              "<%.*s>: "
              "<%.*s>(%u): "
              "record:<%.*s>(%d), "
              "n-postings:<%d>, "
              "n-discarded-postings:<%d>",
              tag,
              name_size, name,
              (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
              tid,
              source_table_name_size, source_table_name,
              u->rid,
              u->atf,
              u->atf - u->tf);
      GRN_OBJ_FIN(ctx, &term);
    }
  }
  grn_ii_expire(ctx, ii);
  return ctx->rc;
}

grn_rc
grn_ii_delete_one(grn_ctx *ctx, grn_ii *ii, grn_id tid, grn_ii_updspec *u, grn_hash *h)
{
  const char *tag = "[ii][delete][one]";
  buffer *b;
  uint8_t *bs = NULL;
  buffer_rec *br;
  buffer_term *bt;
  uint32_t pseg, size, *a;
  if (!tid) { return ctx->rc; }
  if (!(a = array_at(ctx, ii, tid))) {
    return ctx->rc;
  }
  if (grn_ii_wal_touch(ctx, ii, tag) != GRN_SUCCESS) {
    return ctx->rc;
  }
  for (;;) {
    const uint32_t pos = a[0];
    if (pos == 0) { goto exit; }
    if (POS_IS_EMBED(pos)) {
      if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
        const uint32_t rid = POS_RID_SID_EXTRACT_RID(pos);
        const uint32_t sid = POS_RID_SID_EXTRACT_SID(pos);
        if (u->rid == rid && (!u->sid || u->sid == sid)) {
          a[0] = 0;
          lexicon_delete(ctx, ii, tid, h);
        }
      } else {
        const uint32_t rid = POS_RID_EXTRACT(pos);
        if (u->rid == rid) {
          a[0] = 0;
          lexicon_delete(ctx, ii, tid, h);
        }
      }
      goto exit;
    }
    if (!(bs = encode_rec(ctx, ii, u, &size, 1))) {
      grn_obj term;
      GRN_DEFINE_NAME(ii);
      GRN_TEXT_INIT(&term, 0);
      grn_ii_get_term(ctx, ii, tid, &term);
      MERR("%s failed to encode a record: "
           "<%.*s>: "
           "<%.*s>(%u): "
           "(%u:%u)",
           tag,
           name_size, name,
           (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
           tid,
           u->rid, u->sid);
      GRN_OBJ_FIN(ctx, &term);
      goto exit;
    }
    if ((pseg = buffer_open(ctx, ii, pos, &bt, &b)) == GRN_II_PSEG_NOT_ASSIGNED) {
      grn_obj term;
      GRN_DEFINE_NAME(ii);
      GRN_TEXT_INIT(&term, 0);
      grn_ii_get_term(ctx, ii, tid, &term);
      MERR("%s failed to allocate a buffer: "
           "<%.*s>: "
           "<%.*s>(%u): "
           "(%u:%u): "
           "position:<%u>",
           tag,
           name_size, name,
           (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
           tid,
           u->rid, u->sid,
           pos);
      GRN_OBJ_FIN(ctx, &term);
      goto exit;
    }
    if (b->header.buffer_free < size) {
      const uint32_t pos_keep = pos;
      GRN_LOG(ctx, GRN_LOG_DEBUG, "flushing! b=%p free=%d, seg(%d)",
              b, b->header.buffer_free, grn_ii_pos_lseg(ii, pos));
      buffer_close(ctx, ii, pseg);
      buffer_flush(ctx, ii, grn_ii_pos_lseg(ii, pos), h);
      if (ctx->rc != GRN_SUCCESS) {
        grn_obj term;
        char errbuf[GRN_CTX_MSGSIZE];
        GRN_DEFINE_NAME(ii);
        GRN_TEXT_INIT(&term, 0);
        grn_ii_get_term(ctx, ii, tid, &term);
        grn_strcpy(errbuf, GRN_CTX_MSGSIZE, ctx->errbuf);
        ERR(ctx->rc,
            "%s failed to flush a buffer: "
            "<%.*s>: "
            "<%.*s>(%u): "
            "(%u:%u): "
            "position:<%u>: "
            "%s",
            tag,
            name_size, name,
            (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
            tid,
            u->rid, u->sid,
            pos,
            errbuf);
        GRN_OBJ_FIN(ctx, &term);
        goto exit;
      }
      if (a[0] != pos_keep) {
        GRN_LOG(ctx, GRN_LOG_DEBUG, "grn_ii_delete_one: a[0] changed %d->%d)",
                a[0], pos_keep);
        continue;
      }
      if ((pseg = buffer_open(ctx, ii, a[0], &bt, &b)) == GRN_II_PSEG_NOT_ASSIGNED) {
        grn_obj term;
        GRN_DEFINE_NAME(ii);
        GRN_TEXT_INIT(&term, 0);
        grn_ii_get_term(ctx, ii, tid, &term);
        MERR("%s failed to reallocate a buffer: "
             "<%.*s>: "
             "<%.*s>(%u): "
             "(%u:%u): "
             "position:<%u>",
             tag,
             name_size, name,
             (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
             tid,
             u->rid, u->sid,
             a[0]);
        GRN_OBJ_FIN(ctx, &term);
        goto exit;
      }
      GRN_LOG(ctx, GRN_LOG_DEBUG, "flushed!  b=%p free=%d, seg(%d)",
              b, b->header.buffer_free, grn_ii_pos_lseg(ii, a[0]));
      if (b->header.buffer_free < size) {
        grn_obj term;
        GRN_DEFINE_NAME(ii);
        GRN_TEXT_INIT(&term, 0);
        grn_ii_get_term(ctx, ii, tid, &term);
        MERR("%s buffer is full: "
             "<%.*s>: "
             "<%.*s>(%u): "
             "(%u:%u): "
             "segment:<%u>, free:<%u>, required:<%u>",
             tag,
             name_size, name,
             (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
             tid,
             u->rid, u->sid,
             a[0], b->header.buffer_free, size);
        GRN_OBJ_FIN(ctx, &term);
        buffer_close(ctx, ii, pseg);
        goto exit;
      }
    }

    b->header.buffer_free -= size;
    br = (buffer_rec *)(((byte *)&b->terms[b->header.nterms]) + b->header.buffer_free);
    buffer_put(ctx, ii, b, bt, br, bs, u, size);
    buffer_close(ctx, ii, pseg);
    break;
  }
exit :
  array_unref(ctx, ii, tid);
  if (bs) { GRN_FREE(bs); }
  return ctx->rc;
}

#define CHUNK_USED    1
#define BUFFER_USED   2
#define SOLE_DOC_USED 4
#define SOLE_POS_USED 8

struct _grn_ii_cursor {
  grn_db_obj obj;
  grn_ctx *ctx;
  grn_ii *ii;
  grn_id id;
  grn_posting *post;

  grn_id min; /* Minimum record ID */
  grn_id max;
  grn_posting_internal pc;
  grn_posting_internal pb;

  uint32_t cdf;  /* Document frequency */
  uint32_t *cdp;
  uint32_t *crp; /* Record ID */
  uint32_t *csp; /* Section ID */
  uint32_t *ctp; /* Term frequency */
  uint32_t *cwp; /* Weight */
  uint32_t *cpp; /* Position */

  uint8_t *bp;

  uint32_t nelements;
  uint32_t nchunks;
  uint32_t curr_chunk;
  chunk_info *cinfo;
  grn_io_win iw;
  uint8_t *cp;
  uint8_t *cpe;
  datavec rdv[MAX_N_ELEMENTS + 1];

  buffer *buf;
  uint16_t stat;
  uint16_t nextb;
  uint32_t buffer_pseg;
  int flags;
  uint32_t *ppseg;

  int weight;

  uint32_t prev_chunk_rid;

  float scale;
  float *scales;
  size_t n_scales;
};

static grn_bool
buffer_is_reused(grn_ctx *ctx, grn_ii *ii, grn_ii_cursor *c)
{
  if (*c->ppseg != c->buffer_pseg) {
    uint32_t i;
    for (i = ii->header.common->bgqtail; i != ii->header.common->bgqhead;
         i = (i + 1) & (GRN_II_BGQSIZE - 1)) {
      if (ii->header.common->bgqbody[i] == c->buffer_pseg) { return GRN_FALSE; }
    }
    return GRN_TRUE;
  }
  return GRN_FALSE;
}

static int
chunk_is_reused(grn_ctx *ctx, grn_ii *ii, grn_ii_cursor *c, uint32_t offset, uint32_t size)
{
  if (*c->ppseg != c->buffer_pseg) {
    uint32_t i, m, gseg;
    if (size > S_CHUNK) { return 1; }
    if (size > (1 << GRN_II_W_LEAST_CHUNK)) {
      int es = size - 1;
      GRN_BIT_SCAN_REV(es, m);
      m++;
    } else {
      m = GRN_II_W_LEAST_CHUNK;
    }
    gseg = ii->header.common->garbages[m - GRN_II_W_LEAST_CHUNK];
    while (gseg != GRN_II_PSEG_NOT_ASSIGNED) {
      grn_io_win iw;
      grn_ii_ginfo *ginfo = WIN_MAP(ctx, ii->chunk, &iw, gseg, 0, S_GARBAGE,
                                    GRN_IO_RDWR);
      if (!ginfo) { break; }
      for (i = 0; i < ginfo->nrecs; i++) {
        if (ginfo->recs[i] == offset) {
          grn_io_win_unmap(ctx, &iw);
          return 0;
        }
      }
      gseg = ginfo->next;
      grn_io_win_unmap(ctx, &iw);
    }
    return 1;
  }
  return 0;
}

#define GRN_II_CURSOR_CMP(c1,c2) \
  (((c1)->post->rid > (c2)->post->rid) || \
   (((c1)->post->rid == (c2)->post->rid) && \
    (((c1)->post->sid > (c2)->post->sid) || \
     (((c1)->post->sid == (c2)->post->sid) && \
      ((c1)->post->pos > (c2)->post->pos)))))

grn_ii_cursor *
grn_ii_cursor_open(grn_ctx *ctx, grn_ii *ii, grn_id tid,
                   grn_id min, grn_id max, int nelements, int flags)
{
  grn_ii_cursor *c  = NULL;
  uint32_t pos, *a;
  if (!(a = array_at(ctx, ii, tid))) { return NULL; }
  for (;;) {
    c = NULL;
    if (!(pos = a[0])) { goto exit; }
    if (!(c = GRN_CALLOC(sizeof(grn_ii_cursor)))) { goto exit; }
    c->ctx = ctx;
    c->ii = ii;
    c->id = tid;
    c->min = min;
    c->max = max;
    c->nelements = nelements;
    c->flags = flags;
    c->weight = 0;
    c->scale = 1.0;
    c->scales = NULL;
    c->n_scales = 0;
    if (POS_IS_EMBED(pos)) {
      c->stat = 0;
      if ((ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
        c->pb.rid = POS_RID_SID_EXTRACT_RID(pos);
        c->pb.sid = POS_RID_SID_EXTRACT_SID(pos);
      } else {
        c->pb.rid = POS_RID_EXTRACT(pos);
        c->pb.sid = 1;
      }
      c->pb.tf = 1;
      c->pb.weight = 0;
      c->pb.weight_float = c->pb.weight;
      c->pb.pos = a[1];
      c->pb.scale = c->scale;
    } else {
      uint32_t chunk;
      buffer_term *bt;
      c->buffer_pseg = buffer_open(ctx, ii, pos, &bt, &c->buf);
      if (c->buffer_pseg == GRN_II_PSEG_NOT_ASSIGNED) {
        GRN_FREE(c);
        c = NULL;
        goto exit;
      }
      const uint32_t lseg = grn_ii_pos_lseg(ii, pos);
      c->ppseg = grn_ii_get_buffer_pseg_address_inline(ii, lseg);
      if (bt->size_in_chunk && (chunk = c->buf->header.chunk) != GRN_II_PSEG_NOT_ASSIGNED) {
        if (!(c->cp = WIN_MAP(ctx, ii->chunk, &c->iw, chunk, bt->pos_in_chunk,
                              bt->size_in_chunk, GRN_IO_RDONLY))) {
          buffer_close(ctx, ii, c->buffer_pseg);
          GRN_FREE(c);
          c = NULL;
          goto exit;
        }
        if (buffer_is_reused(ctx, ii, c)) {
          grn_ii_cursor_close(ctx, c);
          continue;
        }
        c->cpe = c->cp + bt->size_in_chunk;
        if ((bt->tid & CHUNK_SPLIT)) {
          uint32_t i;
          grn_id crid;
          GRN_B_DEC(c->nchunks, c->cp);
          if (chunk_is_reused(ctx, ii, c, chunk, c->buf->header.chunk_size)) {
            grn_ii_cursor_close(ctx, c);
            continue;
          }
          if (!(c->cinfo = GRN_MALLOCN(chunk_info, c->nchunks))) {
            buffer_close(ctx, ii, c->buffer_pseg);
            grn_io_win_unmap(ctx, &c->iw);
            GRN_FREE(c);
            c = NULL;
            goto exit;
          }
          for (i = 0, crid = GRN_ID_NIL; i < c->nchunks; i++) {
            GRN_B_DEC(c->cinfo[i].segno, c->cp);
            GRN_B_DEC(c->cinfo[i].size, c->cp);
            GRN_B_DEC(c->cinfo[i].dgap, c->cp);
            crid += c->cinfo[i].dgap;
            if (crid < min) {
              c->pc.rid = crid;
              c->curr_chunk = i + 1;
            }
          }
          if (chunk_is_reused(ctx, ii, c, chunk, c->buf->header.chunk_size)) {
            grn_ii_cursor_close(ctx, c);
            continue;
          }
        }
        if ((ii->header.common->flags & GRN_OBJ_WITH_POSITION)) {
          c->rdv[ii->n_elements - 1].flags = ODD;
        }
      }
      c->nextb = bt->pos_in_buffer;
      c->stat = CHUNK_USED|BUFFER_USED;
    }
    if (pos == a[0]) { break; }
    grn_ii_cursor_close(ctx, c);
  }
exit :
  array_unref(ctx, ii, tid);
  return c;
}

grn_ii *
grn_ii_cursor_get_ii(grn_ctx *ctx, grn_ii_cursor *cursor)
{
  return cursor->ii;
}

static grn_inline float
grn_ii_cursor_resolve_scale(grn_ctx *ctx,
                            grn_ii_cursor *cursor,
                            uint32_t section_id)
{
  if (cursor->n_scales > 0) {
    if (section_id <= cursor->n_scales) {
      return cursor->scales[section_id - 1];
    } else {
      return 0.0;
    }
  } else {
    return cursor->scale;
  }
}

grn_rc
grn_ii_cursor_set_scale(grn_ctx *ctx,
                        grn_ii_cursor *cursor,
                        float scale)
{
  cursor->scale = scale;
  cursor->scales = NULL;
  cursor->n_scales = 0;
  if (!cursor->buf) {
    cursor->pb.scale = grn_ii_cursor_resolve_scale(ctx, cursor, cursor->pb.sid);
  }
  return ctx->rc;
}

grn_rc
grn_ii_cursor_set_scales(grn_ctx *ctx,
                         grn_ii_cursor *cursor,
                         float *scales,
                         size_t n_scales)
{
  cursor->scale = 0.0;
  cursor->scales = scales;
  cursor->n_scales = n_scales;
  if (!cursor->buf) {
    cursor->pb.scale = grn_ii_cursor_resolve_scale(ctx, cursor, cursor->pb.sid);
  }
  return ctx->rc;
}

static grn_inline void
grn_ii_cursor_set_min(grn_ctx *ctx, grn_ii_cursor *c, grn_id min)
{
  if (c->min >= min) {
    return;
  }

  if (grn_ii_cursor_set_min_enable) {
    grn_id old_min = c->min;
    c->min = min;
    if (c->buf &&
        c->pc.rid != GRN_ID_NIL &&
        c->pc.rid < c->min &&
        c->prev_chunk_rid < c->min &&
        c->curr_chunk < c->nchunks) {
      uint32_t i;
      uint32_t skip_chunk = 0;
      grn_id rid = c->prev_chunk_rid;

      if (c->curr_chunk > 0) {
        i = c->curr_chunk - 1;
      } else {
        i = 0;
      }
      for (; i < c->nchunks; i++) {
        rid += c->cinfo[i].dgap;
        if (rid < c->min) {
          skip_chunk = i + 1;
        } else {
          rid -= c->cinfo[i].dgap;
          break;
        }
      }
      if (skip_chunk > c->curr_chunk) {
        grn_id old_rid = c->pc.rid;
        grn_id old_prev_chunk_rid = c->prev_chunk_rid;
        uint32_t old_chunk = c->curr_chunk;
        grn_bool old_chunk_used = (c->stat & CHUNK_USED);
        c->pc.rid = rid;
        c->pc.rest = 0;
        c->prev_chunk_rid = rid - c->cinfo[skip_chunk - 1].dgap;
        c->curr_chunk = skip_chunk;
        c->crp = c->cdp + c->cdf;
        c->stat |= CHUNK_USED;
        if (grn_logger_pass(ctx, GRN_LOG_DEBUG)) {
          GRN_DEFINE_NAME(c->ii);
          grn_obj term;
          GRN_TEXT_INIT(&term, 0);
          grn_ii_get_term(ctx, c->ii, c->id, &term);
          GRN_LOG(ctx, GRN_LOG_DEBUG,
                  "[ii][cursor][min][%.*s][%.*s][%u] skip: "
                  "<%p>: "
                  "rid(%u->%u): "
                  "prev-chunk-rid(%u->%u): "
                  "min(%u->%u): "
                  "chunk(%u->%u): "
                  "chunk-used(%s->%s)",
                  name_size, name,
                  (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                  c->id,
                  c,
                  old_rid, rid,
                  old_prev_chunk_rid, c->prev_chunk_rid,
                  old_min, min,
                  old_chunk, c->curr_chunk,
                  old_chunk_used ? "true" : "false",
                  (c->stat & CHUNK_USED) ? "true" : "false");
          GRN_OBJ_FIN(ctx, &term);
        }
      }
    }
  }
}

typedef struct {
  grn_bool include_garbage;
} grn_ii_cursor_next_options;

static grn_inline grn_posting *
grn_ii_cursor_next_internal(grn_ctx *ctx, grn_ii_cursor *c,
                            grn_ii_cursor_next_options *options)
{
  const grn_bool include_garbage = options->include_garbage;
  if (c->buf) {
    for (;;) {
      if (c->stat & CHUNK_USED) {
        for (;;) {
          if (c->crp < c->cdp + c->cdf) {
            uint32_t dgap = *c->crp++;
            c->pc.rid += dgap;
            if (dgap) { c->pc.sid = 0; }
            if ((c->ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
              c->pc.sid += 1 + *c->csp++;
            } else {
              c->pc.sid = 1;
            }
            c->cpp += c->pc.rest;
            c->pc.rest = c->pc.tf = 1 + *c->ctp++;
            if ((c->ii->header.common->flags & GRN_OBJ_WITH_WEIGHT)) {
              c->pc.weight = *c->cwp++;
            } else {
              c->pc.weight = 0;
            }
            c->pc.weight_float = c->pc.weight;
            c->pc.pos = 0;
            c->pc.scale = grn_ii_cursor_resolve_scale(ctx, c, c->pc.sid);
            /*
            {
              static int count = 0;
              int tf = c->pc.tf, pos = 0, *pp = (int *)c->cpp;
              grn_obj buf;
              GRN_TEXT_INIT(&buf, 0);
              grn_text_itoa(ctx, &buf, c->pc.rid);
              GRN_TEXT_PUTC(ctx, &buf, ':');
              grn_text_itoa(ctx, &buf, c->pc.sid);
              GRN_TEXT_PUTC(ctx, &buf, ':');
              grn_text_itoa(ctx, &buf, c->pc.tf);
              GRN_TEXT_PUTC(ctx, &buf, '(');
              while (tf--) {
                pos += *pp++;
                count++;
                grn_text_itoa(ctx, &buf, pos);
                if (tf) { GRN_TEXT_PUTC(ctx, &buf, ':'); }
              }
              GRN_TEXT_PUTC(ctx, &buf, ')');
              GRN_TEXT_PUTC(ctx, &buf, '\0');
              GRN_LOG(ctx, GRN_LOG_DEBUG, "posting(%d):%s", count, GRN_TEXT_VALUE(&buf));
              GRN_OBJ_FIN(ctx, &buf);
            }
            */
            if (c->pc.rid < c->min ||
                c->pc.scale <= 0.0) {
              continue;
            }
          } else {
            if (c->curr_chunk <= c->nchunks) {
              if (c->curr_chunk == c->nchunks) {
                if (c->cp < c->cpe) {
                  int decoded_size;
                  decoded_size =
                    grn_p_decv(ctx, c->ii, c->id,
                               c->cp, c->cpe - c->cp,
                               c->rdv, c->ii->n_elements);
                  if (decoded_size == 0) {
                    GRN_DEFINE_NAME(c->ii);
                    grn_obj term;
                    GRN_TEXT_INIT(&term, 0);
                    grn_ii_get_term(ctx, c->ii, c->id, &term);
                    GRN_LOG(ctx, GRN_LOG_WARNING,
                            "[ii][cursor][next][chunk][last][%.*s][%*.s][%u] "
                            "failed to decode the last chunk. "
                            "Another thread might change "
                            "the chunk while decoding: "
                            "<%p>: <%d>: <%" GRN_FMT_INT64D ">",
                            name_size, name,
                            (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                            c->id,
                            c,
                            c->curr_chunk,
                            c->cinfo ?
                            (int64_t)(c->cinfo[c->curr_chunk].segno) :
                            -1);
                    GRN_OBJ_FIN(ctx, &term);
                    c->pc.rid = GRN_ID_NIL;
                    break;
                  }
                  if (buffer_is_reused(ctx, c->ii, c)) {
                    GRN_DEFINE_NAME(c->ii);
                    grn_obj term;
                    GRN_TEXT_INIT(&term, 0);
                    grn_ii_get_term(ctx, c->ii, c->id, &term);
                    GRN_LOG(ctx, GRN_LOG_WARNING,
                            "[ii][cursor][next][chunk][last][%.*s][%*.s][%u] "
                            "buffer is reused by another thread: <%p>",
                            name_size, name,
                            (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                            c->id,
                            c);
                    GRN_OBJ_FIN(ctx, &term);
                    c->pc.rid = GRN_ID_NIL;
                    break;
                  }
                  if (chunk_is_reused(ctx, c->ii, c,
                                      c->buf->header.chunk,
                                      c->buf->header.chunk_size)) {
                    GRN_DEFINE_NAME(c->ii);
                    grn_obj term;
                    GRN_TEXT_INIT(&term, 0);
                    grn_ii_get_term(ctx, c->ii, c->id, &term);
                    GRN_LOG(ctx, GRN_LOG_WARNING,
                            "[ii][cursor][next][chunk][last][%.*s][%*.s][%u] "
                            "chunk is reused by another thread: "
                            "<%p>: <%d>",
                            name_size, name,
                            (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                            c->id,
                            c,
                            c->buf->header.chunk);
                    GRN_OBJ_FIN(ctx, &term);
                    c->pc.rid = GRN_ID_NIL;
                    break;
                  }
                } else {
                  c->pc.rid = GRN_ID_NIL;
                  break;
                }
              } else {
                uint8_t *cp;
                grn_io_win iw;
                uint32_t size = c->cinfo[c->curr_chunk].size;
                if (size && (cp = WIN_MAP(ctx, c->ii->chunk, &iw,
                                          c->cinfo[c->curr_chunk].segno, 0,
                                          size, GRN_IO_RDONLY))) {
                  int decoded_size;
                  decoded_size =
                    grn_p_decv(ctx, c->ii, c->id,
                               cp, size, c->rdv, c->ii->n_elements);
                  grn_io_win_unmap(ctx, &iw);
                  if (decoded_size == 0) {
                    GRN_DEFINE_NAME(c->ii);
                    grn_obj term;
                    GRN_TEXT_INIT(&term, 0);
                    grn_ii_get_term(ctx, c->ii, c->id, &term);
                    GRN_LOG(ctx, GRN_LOG_WARNING,
                            "[ii][cursor][next][chunk][%.*s][%.*s][%u]  "
                            "failed to decode the next chunk. "
                            "Another thread might change "
                            "the chunk while decoding: "
                            "<%p>: <%d>: <%" GRN_FMT_INT64D ">",
                            name_size, name,
                            (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                            c->id,
                            c,
                            c->curr_chunk,
                            c->cinfo ?
                            (int64_t)(c->cinfo[c->curr_chunk].segno) :
                            -1);
                    GRN_OBJ_FIN(ctx, &term);
                    c->pc.rid = GRN_ID_NIL;
                    break;
                  }
                  if (buffer_is_reused(ctx, c->ii, c)) {
                    GRN_DEFINE_NAME(c->ii);
                    grn_obj term;
                    GRN_TEXT_INIT(&term, 0);
                    grn_ii_get_term(ctx, c->ii, c->id, &term);
                    GRN_LOG(ctx, GRN_LOG_WARNING,
                            "[ii][cursor][next][chunk][%.*s][%*.s][%u] "
                            "buffer is reused by another thread: <%p>",
                            name_size, name,
                            (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                            c->id,
                            c);
                    GRN_OBJ_FIN(ctx, &term);
                    c->pc.rid = GRN_ID_NIL;
                    break;
                  }
                  if (chunk_is_reused(ctx, c->ii, c,
                                      c->cinfo[c->curr_chunk].segno, size)) {
                    GRN_DEFINE_NAME(c->ii);
                    grn_obj term;
                    GRN_TEXT_INIT(&term, 0);
                    grn_ii_get_term(ctx, c->ii, c->id, &term);
                    GRN_LOG(ctx, GRN_LOG_WARNING,
                            "[ii][cursor][next][chunk][%*.s][%*.s][%u] "
                            "chunk is reused by another thread: "
                            "<%p>: <%d>",
                            name_size, name,
                            (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                            c->id,
                            c,
                            c->cinfo[c->curr_chunk].segno);
                    GRN_OBJ_FIN(ctx, &term);
                    c->pc.rid = GRN_ID_NIL;
                    break;
                  }
                } else {
                  c->pc.rid = GRN_ID_NIL;
                  break;
                }
              }
              {
                int j = 0;
                c->cdf = c->rdv[j].data_size;
                c->crp = c->cdp = c->rdv[j++].data;
                if ((c->ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
                  c->csp = c->rdv[j++].data;
                }
                c->ctp = c->rdv[j++].data;
                if ((c->ii->header.common->flags & GRN_OBJ_WITH_WEIGHT)) {
                  c->cwp = c->rdv[j++].data;
                }
                if ((c->ii->header.common->flags & GRN_OBJ_WITH_POSITION)) {
                  c->cpp = c->rdv[j].data;
                }
              }
              c->prev_chunk_rid = c->pc.rid;
              c->pc.rid = GRN_ID_NIL;
              c->pc.sid = 0;
              c->pc.rest = 0;
              c->curr_chunk++;
              continue;
            } else {
              c->pc.rid = GRN_ID_NIL;
            }
          }
          break;
        }
      }
      if (c->stat & BUFFER_USED) {
        for (;;) {
          if (c->nextb) {
            uint32_t lrid = c->pb.rid, lsid = c->pb.sid; /* for check */
            buffer_rec *br = BUFFER_REC_AT(c->buf, c->nextb);
            if (buffer_is_reused(ctx, c->ii, c)) {
              GRN_DEFINE_NAME(c->ii);
              grn_obj term;
              GRN_TEXT_INIT(&term, 0);
              grn_ii_get_term(ctx, c->ii, c->id, &term);
              GRN_LOG(ctx, GRN_LOG_WARNING,
                      "[ii][cursor][next][buffer][%*.s][%*.s][%u] "
                      "buffer is reused by another thread: "
                      "<%p>: <%d>: <%d>",
                      name_size, name,
                      (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                      c->id,
                      c,
                      c->buffer_pseg,
                      *c->ppseg);
              GRN_OBJ_FIN(ctx, &term);
              c->pb.rid = GRN_ID_NIL;
              break;
            }
            c->bp = GRN_NEXT_ADDR(br);
            GRN_B_DEC(c->pb.rid, c->bp);
            if ((c->ii->header.common->flags & GRN_OBJ_WITH_SECTION)) {
              GRN_B_DEC(c->pb.sid, c->bp);
            } else {
              c->pb.sid = 1;
            }
            if (lrid > c->pb.rid || (lrid == c->pb.rid && lsid >= c->pb.sid)) {
              GRN_DEFINE_NAME(c->ii);
              grn_obj term;
              GRN_TEXT_INIT(&term, 0);
              grn_ii_get_term(ctx, c->ii, c->id, &term);
              ERR(GRN_FILE_CORRUPT,
                  "[ii][broken][cursor][next][buffer][%*.s][%*.s][%u] "
                  "posting in list in buffer isn't sorted: "
                  "(%d:%d) -> (%d:%d) (%d->%d)",
                  name_size, name,
                  (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                  c->id,
                  lrid, lsid,
                  c->pb.rid, c->pb.sid,
                  c->buffer_pseg, *c->ppseg);
              GRN_OBJ_FIN(ctx, &term);
              c->pb.rid = GRN_ID_NIL;
              break;
            }
            c->pb.scale = grn_ii_cursor_resolve_scale(ctx, c, c->pb.sid);
            if (c->pb.rid < c->min ||
                c->pb.scale <= 0.0) {
              c->pb.rid = 0;
              if (br->jump > 0 && !BUFFER_REC_DELETED(br)) {
                buffer_rec *jump_br = BUFFER_REC_AT(c->buf, br->jump);
                if (BUFFER_REC_DELETED(jump_br)) {
                  c->nextb = br->step;
                } else {
                  uint8_t *jump_bp;
                  uint32_t jump_rid;
                  jump_bp = GRN_NEXT_ADDR(jump_br);
                  GRN_B_DEC(jump_rid, jump_bp);
                  if (jump_rid < c->min) {
                    c->nextb = br->jump;
                  } else {
                    c->nextb = br->step;
                  }
                }
              } else {
                c->nextb = br->step;
              }
              continue;
            }
            c->nextb = br->step;
            GRN_B_DEC(c->pb.tf, c->bp);
            if ((c->ii->header.common->flags & GRN_OBJ_WITH_WEIGHT)) {
              GRN_B_DEC(c->pb.weight, c->bp);
            } else {
              c->pb.weight = 0;
            }
            c->pb.weight_float = c->pb.weight;
            c->pb.rest = c->pb.tf;
            c->pb.pos = 0;
          } else {
            c->pb.rid = 0;
          }
          break;
        }
      }
      if (c->pb.rid) {
        if (c->pc.rid) {
          if (c->pc.rid < c->pb.rid) {
            c->stat = CHUNK_USED;
            if (include_garbage || (c->pc.tf && c->pc.sid)) {
              c->post = (grn_posting *)(&c->pc);
              break;
            }
          } else {
            if (c->pb.rid < c->pc.rid) {
              c->stat = BUFFER_USED;
              if (include_garbage || (c->pb.tf && c->pb.sid)) {
                c->post = (grn_posting *)(&c->pb);
                break;
              }
            } else {
              if (c->pb.sid) {
                if (c->pc.sid < c->pb.sid) {
                  c->stat = CHUNK_USED;
                  if (include_garbage || (c->pc.tf && c->pc.sid)) {
                    c->post = (grn_posting *)(&c->pc);
                    break;
                  }
                } else {
                  c->stat = BUFFER_USED;
                  if (c->pb.sid == c->pc.sid) { c->stat |= CHUNK_USED; }
                  if (include_garbage || (c->pb.tf)) {
                    c->post = (grn_posting *)(&c->pb);
                    break;
                  }
                }
              } else {
                c->stat = CHUNK_USED;
              }
            }
          }
        } else {
          c->stat = BUFFER_USED;
          if (include_garbage || (c->pb.tf && c->pb.sid)) {
            c->post = (grn_posting *)(&c->pb);
            break;
          }
        }
      } else {
        if (c->pc.rid) {
          c->stat = CHUNK_USED;
          if (include_garbage || (c->pc.tf && c->pc.sid)) {
            c->post = (grn_posting *)(&c->pc);
            break;
          }
        } else {
          c->post = NULL;
          return NULL;
        }
      }
    }
  } else {
    if (c->stat & SOLE_DOC_USED) {
      c->post = NULL;
      return NULL;
    } else {
      c->post = (grn_posting *)(&c->pb);
      c->stat |= SOLE_DOC_USED;
      if (c->post->rid < c->min) {
        c->post = NULL;
        return NULL;
      }
      if (c->pb.scale <= 0.0) {
        c->post = NULL;
        return NULL;
      }
    }
  }
  return c->post;
}

grn_posting *
grn_ii_cursor_next(grn_ctx *ctx, grn_ii_cursor *c)
{
  grn_ii_cursor_next_options options = {
    .include_garbage = GRN_FALSE
  };
  return grn_ii_cursor_next_internal(ctx, c, &options);
}

grn_posting *
grn_ii_cursor_next_pos(grn_ctx *ctx, grn_ii_cursor *c)
{
  uint32_t gap;
  if ((c->ii->header.common->flags & GRN_OBJ_WITH_POSITION)) {
    if (c->nelements == c->ii->n_elements) {
      if (c->buf) {
        if (c->post == (grn_posting *)(&c->pc)) {
          if (c->pc.rest) {
            c->pc.rest--;
            c->pc.pos += *c->cpp++;
          } else {
            return NULL;
          }
        } else if (c->post == (grn_posting *)(&c->pb)) {
          if (buffer_is_reused(ctx, c->ii, c)) {
            GRN_DEFINE_NAME(c->ii);
            grn_obj term;
            GRN_TEXT_INIT(&term, 0);
            grn_ii_get_term(ctx, c->ii, c->id, &term);
            GRN_LOG(ctx, GRN_LOG_WARNING,
                    "[ii][cursor][next][pos][buffer][%.*s][%.*s][%u] "
                    "buffer(%d,%d) is reused by another thread: %p",
                    name_size, name,
                    (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                    c->id,
                    c->buffer_pseg, *c->ppseg,
                    c);
            GRN_OBJ_FIN(ctx, &term);
            return NULL;
          }
          if (c->pb.rest) {
            c->pb.rest--;
            GRN_B_DEC(gap, c->bp);
            c->pb.pos += gap;
          } else {
            return NULL;
          }
        } else {
          return NULL;
        }
      } else {
        if (c->stat & SOLE_POS_USED) {
          return NULL;
        } else {
          c->stat |= SOLE_POS_USED;
        }
      }
    }
  } else {
    if (c->stat & SOLE_POS_USED) {
      return NULL;
    } else {
      c->stat |= SOLE_POS_USED;
    }
  }
  return c->post;
}

grn_rc
grn_ii_cursor_close(grn_ctx *ctx, grn_ii_cursor *c)
{
  if (!c) { return GRN_INVALID_ARGUMENT; }
  datavec_fin(ctx, c->rdv);
  if (c->cinfo) { GRN_FREE(c->cinfo); }
  if (c->buf) { buffer_close(ctx, c->ii, c->buffer_pseg); }
  if (c->cp) { grn_io_win_unmap(ctx, &c->iw); }
  GRN_FREE(c);
  return GRN_SUCCESS;
}

uint32_t
grn_ii_get_chunksize(grn_ctx *ctx, grn_ii *ii, grn_id tid)
{
  uint32_t res, pos, *a;
  a = array_at(ctx, ii, tid);
  if (!a) { return 0; }
  if ((pos = a[0])) {
    if (POS_IS_EMBED(pos)) {
      res = 0;
    } else {
      buffer *buf;
      uint32_t pseg;
      buffer_term *bt;
      if ((pseg = buffer_open(ctx, ii, pos, &bt, &buf)) == GRN_II_PSEG_NOT_ASSIGNED) {
        res = 0;
      } else {
        res = bt->size_in_chunk;
        buffer_close(ctx, ii, pseg);
      }
    }
  } else {
    res = 0;
  }
  array_unref(ctx, ii, tid);
  return res;
}

uint32_t
grn_ii_estimate_size(grn_ctx *ctx, grn_ii *ii, grn_id tid)
{
  uint32_t res, pos, *a;
  a = array_at(ctx, ii, tid);
  if (!a) { return 0; }
  if ((pos = a[0])) {
    if (POS_IS_EMBED(pos)) {
      res = 1;
    } else {
      buffer *buf;
      uint32_t pseg;
      buffer_term *bt;
      if ((pseg = buffer_open(ctx, ii, pos, &bt, &buf)) == GRN_II_PSEG_NOT_ASSIGNED) {
        res = 0;
      } else {
        res = a[1] + bt->size_in_buffer + 2;
        buffer_close(ctx, ii, pseg);
      }
    }
  } else {
    res = 0;
  }
  array_unref(ctx, ii, tid);
  return res;
}

int
grn_ii_entry_info(grn_ctx *ctx, grn_ii *ii, grn_id tid, unsigned int *a,
                   unsigned int *chunk, unsigned int *chunk_size,
                   unsigned int *buffer_free,
                   unsigned int *nterms, unsigned int *nterms_void,
                   unsigned int *bt_tid,
                   unsigned int *size_in_chunk, unsigned int *pos_in_chunk,
                   unsigned int *size_in_buffer, unsigned int *pos_in_buffer)
{
  buffer *b;
  buffer_term *bt;
  uint32_t pseg, *ap;
  ERRCLR(NULL);
  ap = array_at(ctx, ii, tid);
  if (!ap) { return 0; }
  a[0] = *ap;
  array_unref(ctx, ii, tid);
  if (!a[0]) { return 1; }
  if (POS_IS_EMBED(a[0])) { return 2; }
  if ((pseg = buffer_open(ctx, ii, a[0], &bt, &b)) == GRN_II_PSEG_NOT_ASSIGNED) { return 3; }
  *chunk = b->header.chunk;
  *chunk_size = b->header.chunk_size;
  *buffer_free = b->header.buffer_free;
  *nterms = b->header.nterms;
  *bt_tid = bt->tid;
  *size_in_chunk = bt->size_in_chunk;
  *pos_in_chunk = bt->pos_in_chunk;
  *size_in_buffer = bt->size_in_buffer;
  *pos_in_buffer = bt->pos_in_buffer;
  buffer_close(ctx, ii, pseg);
  return 4;
}

uint32_t
grn_ii_get_array_pseg(grn_ii *ii,
                      uint32_t lseg)
{
  return grn_ii_get_array_pseg_inline(ii, lseg);
}

uint32_t
grn_ii_get_buffer_pseg(grn_ii *ii,
                       uint32_t lseg)
{
  return grn_ii_get_buffer_pseg_inline(ii, lseg);
}

uint32_t
grn_ii_n_logical_segments(grn_ii *ii)
{
  return grn_ii_n_logical_segments_inline(ii);
}

const char *
grn_ii_path(grn_ii *ii)
{
  return grn_io_path(ii->seg);
}

uint32_t
grn_ii_max_section(grn_ii *ii)
{
  return ii->header.common->smax;
}

grn_obj *
grn_ii_lexicon(grn_ii *ii)
{
  return ii->lexicon;
}

/* private classes */

/* b-heap */

typedef struct {
  int n_entries;
  int n_bins;
  grn_ii_cursor **bins;
} cursor_heap;

static grn_inline cursor_heap *
cursor_heap_open(grn_ctx *ctx, int max)
{
  cursor_heap *h = GRN_CALLOC(sizeof(cursor_heap));
  if (!h) { return NULL; }
  h->bins = GRN_MALLOC(sizeof(grn_ii_cursor *) * max);
  if (!h->bins) {
    GRN_FREE(h);
    return NULL;
  }
  h->n_entries = 0;
  h->n_bins = max;
  return h;
}

static grn_inline grn_rc
cursor_heap_push(grn_ctx *ctx, cursor_heap *h, grn_ii *ii, grn_id tid, uint32_t offset2,
                 int weight, grn_id min)
{
  int n, n2;
  grn_ii_cursor *c, *c2;
  if (h->n_entries >= h->n_bins) {
    int max = h->n_bins * 2;
    grn_ii_cursor **bins = GRN_REALLOC(h->bins, sizeof(grn_ii_cursor *) * max);
    GRN_LOG(ctx, GRN_LOG_DEBUG, "expanded cursor_heap to %d,%p", max, bins);
    if (!bins) { return GRN_NO_MEMORY_AVAILABLE; }
    h->n_bins = max;
    h->bins = bins;
  }
  {
    if (!(c = grn_ii_cursor_open(ctx, ii, tid, min, GRN_ID_MAX,
                                 ii->n_elements, 0))) {
      GRN_LOG(ctx, GRN_LOG_ERROR, "cursor open failed");
      return ctx->rc;
    }
    if (!grn_ii_cursor_next(ctx, c)) {
      grn_ii_cursor_close(ctx, c);
      return GRN_END_OF_DATA;
    }
    if (!grn_ii_cursor_next_pos(ctx, c)) {
      if (grn_logger_pass(ctx, GRN_LOG_ERROR)) {
        GRN_DEFINE_NAME(c->ii);
        grn_obj term;
        GRN_TEXT_INIT(&term, 0);
        grn_ii_get_term(ctx, c->ii, c->id, &term);
        GRN_LOG(ctx, GRN_LOG_ERROR,
                "[ii][cursor][heap][push][%*.s][%*.s][%u] "
                "invalid cursor: <%p>",
                name_size, name,
                (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                c->id,
                c);
        GRN_OBJ_FIN(ctx, &term);
      }
      grn_ii_cursor_close(ctx, c);
      return GRN_END_OF_DATA;
    }
    if (weight) {
      c->weight = weight;
    }
    n = h->n_entries++;
    while (n) {
      n2 = (n - 1) >> 1;
      c2 = h->bins[n2];
      if (GRN_II_CURSOR_CMP(c, c2)) { break; }
      h->bins[n] = c2;
      n = n2;
    }
    h->bins[n] = c;
  }
  return GRN_SUCCESS;
}

static grn_inline grn_rc
cursor_heap_push2(cursor_heap *h)
{
  grn_rc rc = GRN_SUCCESS;
  return rc;
}

static grn_inline grn_ii_cursor *
cursor_heap_min(cursor_heap *h)
{
  return h->n_entries ? h->bins[0] : NULL;
}

static grn_inline void
cursor_heap_recalc_min(cursor_heap *h)
{
  int n = 0, n1, n2, m;
  if ((m = h->n_entries) > 1) {
    grn_ii_cursor *c = h->bins[0], *c1, *c2;
    for (;;) {
      n1 = n * 2 + 1;
      n2 = n1 + 1;
      c1 = n1 < m ? h->bins[n1] : NULL;
      c2 = n2 < m ? h->bins[n2] : NULL;
      if (c1 && GRN_II_CURSOR_CMP(c, c1)) {
        if (c2 && GRN_II_CURSOR_CMP(c, c2) && GRN_II_CURSOR_CMP(c1, c2)) {
          h->bins[n] = c2;
          n = n2;
        } else {
          h->bins[n] = c1;
          n = n1;
        }
      } else {
        if (c2 && GRN_II_CURSOR_CMP(c, c2)) {
          h->bins[n] = c2;
          n = n2;
        } else {
          h->bins[n] = c;
          break;
        }
      }
    }
  }
}

static grn_inline void
cursor_heap_pop(grn_ctx *ctx, cursor_heap *h, grn_id min)
{
  if (h->n_entries) {
    grn_ii_cursor *c = h->bins[0];
    grn_ii_cursor_set_min(ctx, c, min);
    if (!grn_ii_cursor_next(ctx, c)) {
      grn_ii_cursor_close(ctx, c);
      h->bins[0] = h->bins[--h->n_entries];
    } else if (!grn_ii_cursor_next_pos(ctx, c)) {
      if (grn_logger_pass(ctx, GRN_LOG_ERROR)) {
        GRN_DEFINE_NAME(c->ii);
        grn_obj term;
        GRN_TEXT_INIT(&term, 0);
        grn_ii_get_term(ctx, c->ii, c->id, &term);
        GRN_LOG(ctx, GRN_LOG_ERROR,
                "[ii][cursor][heap][pop][%.*s][%.*s][%u] invalid cursor: <%p>",
                name_size, name,
                (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                c->id,
                c);
        GRN_OBJ_FIN(ctx, &term);
      }
      grn_ii_cursor_close(ctx, c);
      h->bins[0] = h->bins[--h->n_entries];
    }
    if (h->n_entries > 1) { cursor_heap_recalc_min(h); }
  }
}

static grn_inline void
cursor_heap_pop_pos(grn_ctx *ctx, cursor_heap *h)
{
  if (h->n_entries) {
    grn_ii_cursor *c = h->bins[0];
    if (!grn_ii_cursor_next_pos(ctx, c)) {
      if (!grn_ii_cursor_next(ctx, c)) {
        grn_ii_cursor_close(ctx, c);
        h->bins[0] = h->bins[--h->n_entries];
      } else if (!grn_ii_cursor_next_pos(ctx, c)) {
        if (grn_logger_pass(ctx, GRN_LOG_ERROR)) {
          GRN_DEFINE_NAME(c->ii);
          grn_obj term;
          GRN_TEXT_INIT(&term, 0);
          grn_ii_get_term(ctx, c->ii, c->id, &term);
          GRN_LOG(ctx, GRN_LOG_ERROR,
                  "[ii][cursor][heap][pop][position][%.*s][%.*s][%u] "
                  "invalid cursor: <%p>",
                  name_size, name,
                  (int)GRN_TEXT_LEN(&term), GRN_TEXT_VALUE(&term),
                  c->id,
                  c);
          GRN_OBJ_FIN(ctx, &term);
        }
        grn_ii_cursor_close(ctx, c);
        h->bins[0] = h->bins[--h->n_entries];
      }
    }
    if (h->n_entries > 1) { cursor_heap_recalc_min(h); }
  }
}

static grn_inline void
cursor_heap_close(grn_ctx *ctx, cursor_heap *h)
{
  int i;
  if (!h) { return; }
  for (i = h->n_entries; i--;) { grn_ii_cursor_close(ctx, h->bins[i]); }
  GRN_FREE(h->bins);
  GRN_FREE(h);
}

/* update */
#ifdef USE_VGRAM

grn_inline static grn_rc
index_add(grn_ctx *ctx, grn_id rid, grn_obj *lexicon, grn_ii *ii, grn_vgram *vgram,
          const char *value, size_t value_len)
{
  grn_hash *h;
  unsigned int token_flags = 0;
  grn_token_cursor *token_cursor;
  grn_ii_updspec **u;
  grn_id tid, *tp;
  grn_rc r, rc = GRN_SUCCESS;
  grn_vgram_buf *sbuf = NULL;
  if (!rid) { return GRN_INVALID_ARGUMENT; }
  if (!(token_cursor = grn_token_cursor_open(ctx, lexicon, value, value_len,
                                             GRN_TOKEN_ADD, token_flags))) {
    return GRN_NO_MEMORY_AVAILABLE;
  }
  if (vgram) { sbuf = grn_vgram_buf_open(value_len); }
  h = grn_hash_create(ctx, NULL, sizeof(grn_id), sizeof(grn_ii_updspec *),
                      GRN_HASH_TINY);
  if (!h) {
    GRN_LOG(ctx, GRN_LOG_ALERT, "grn_hash_create on index_add failed !");
    grn_token_cursor_close(ctx, token_cursor);
    if (sbuf) { grn_vgram_buf_close(sbuf); }
    return GRN_NO_MEMORY_AVAILABLE;
  }
  while (!token_cursor->status) {
    tid = grn_token_cursor_next(ctx, token_cursor);
    if (tid) {
      if (!grn_hash_add(ctx, h, &tid, sizeof(grn_id), (void **) &u, NULL)) {
        break;
      }
      if (!*u) {
        if (!(*u = grn_ii_updspec_open(ctx, rid, 1))) {
          GRN_LOG(ctx, GRN_LOG_ERROR,
                  "grn_ii_updspec_open on index_add failed!");
          goto exit;
        }
      }
      if (grn_ii_updspec_add(ctx, *u, token_cursor->pos, 0)) {
        GRN_LOG(ctx, GRN_LOG_ERROR,
                "grn_ii_updspec_add on index_add failed!");
        goto exit;
      }
      if (sbuf) { grn_vgram_buf_add(sbuf, tid); }
    }
  }
  grn_token_cursor_close(ctx, token_cursor);
  // todo : support vgram
  //  if (sbuf) { grn_vgram_update(vgram, rid, sbuf, (grn_set *)h); }
  GRN_HASH_EACH(ctx, h, id, &tp, NULL, &u, {
    if ((r = grn_ii_update_one(ctx, ii, *tp, *u, h))) { rc = r; }
    grn_ii_updspec_close(ctx, *u);
  });
  grn_hash_close(ctx, h);
  if (sbuf) { grn_vgram_buf_close(sbuf); }
  return rc;
exit:
  grn_hash_close(ctx, h);
  grn_token_cursor_close(ctx, token_cursor);
  if (sbuf) { grn_vgram_buf_close(sbuf); }
  return GRN_NO_MEMORY_AVAILABLE;
}

grn_inline static grn_rc
index_del(grn_ctx *ctx, grn_id rid, grn_obj *lexicon, grn_ii *ii, grn_vgram *vgram,
          const char *value, size_t value_len)
{
  grn_rc rc = GRN_SUCCESS;
  grn_hash *h;
  unsigned int token_flags = 0;
  grn_token_cursor *token_cursor;
  grn_ii_updspec **u;
  grn_id tid, *tp;
  if (!rid) { return GRN_INVALID_ARGUMENT; }
  if (!(token_cursor = grn_token_cursor_open(ctx, lexicon, value, value_len,
                                             GRN_TOKEN_DEL, token_flags))) {
    return GRN_NO_MEMORY_AVAILABLE;
  }
  h = grn_hash_create(ctx, NULL, sizeof(grn_id), sizeof(grn_ii_updspec *),
                      GRN_HASH_TINY);
  if (!h) {
    GRN_LOG(ctx, GRN_LOG_ALERT, "grn_hash_create on index_del failed !");
    grn_token_cursor_close(ctx, token_cursor);
    return GRN_NO_MEMORY_AVAILABLE;
  }
  while (!token_cursor->status) {
    if ((tid = grn_token_cursor_next(ctx, token_cursor))) {
      if (!grn_hash_add(ctx, h, &tid, sizeof(grn_id), (void **) &u, NULL)) {
        break;
      }
      if (!*u) {
        if (!(*u = grn_ii_updspec_open(ctx, rid, 0))) {
          GRN_LOG(ctx, GRN_LOG_ALERT,
                  "grn_ii_updspec_open on index_del failed !");
          grn_hash_close(ctx, h);
          grn_token_cursor_close(ctx, token_cursor);
          return GRN_NO_MEMORY_AVAILABLE;
        }
      }
    }
  }
  grn_token_cursor_close(ctx, token_cursor);
  GRN_HASH_EACH(ctx, h, id, &tp, NULL, &u, {
    if (*tp) {
      grn_rc r;
      r = grn_ii_delete_one(ctx, ii, *tp, *u, NULL);
      if (r) {
        rc = r;
      }
    }
    grn_ii_updspec_close(ctx, *u);
  });
  grn_hash_close(ctx, h);
  return rc;
}

grn_rc
grn_ii_upd(grn_ctx *ctx, grn_ii *ii, grn_id rid, grn_vgram *vgram,
            const char *oldvalue, unsigned int oldvalue_len,
            const char *newvalue, unsigned int newvalue_len)
{
  grn_rc rc;
  grn_obj *lexicon = ii->lexicon;
  if (!rid) { return GRN_INVALID_ARGUMENT; }
  if (oldvalue && *oldvalue) {
    if ((rc = index_del(ctx, rid, lexicon, ii, vgram, oldvalue, oldvalue_len))) {
      GRN_LOG(ctx, GRN_LOG_ERROR, "index_del on grn_ii_upd failed !");
      goto exit;
    }
  }
  if (newvalue && *newvalue) {
    rc = index_add(ctx, rid, lexicon, ii, vgram, newvalue, newvalue_len);
  }
exit :
  return rc;
}

grn_rc
grn_ii_update(grn_ctx *ctx, grn_ii *ii, grn_id rid, grn_vgram *vgram, unsigned int section,
              grn_values *oldvalues, grn_values *newvalues)
{
  int j;
  grn_value *v;
  unsigned int token_flags = 0;
  grn_token_cursor *token_cursor;
  grn_rc rc = GRN_SUCCESS;
  grn_hash *old, *new;
  grn_id tid, *tp;
  grn_ii_updspec **u, **un;
  grn_obj *lexicon = ii->lexicon;
  if (!lexicon || !ii || !rid) {
    GRN_LOG(ctx, GRN_LOG_WARNING, "grn_ii_update: invalid argument");
    return GRN_INVALID_ARGUMENT;
  }
  if (newvalues) {
    new = grn_hash_create(ctx, NULL, sizeof(grn_id), sizeof(grn_ii_updspec *),
                          GRN_HASH_TINY);
    if (!new) {
      GRN_LOG(ctx, GRN_LOG_ALERT, "grn_hash_create on grn_ii_update failed !");
      rc = GRN_NO_MEMORY_AVAILABLE;
      goto exit;
    }
    for (j = newvalues->n_values, v = newvalues->values; j; j--, v++) {
      if ((token_cursor = grn_token_cursor_open(ctx, lexicon, v->str,
                                                v->str_len, GRN_TOKEN_ADD,
                                                token_flags))) {
        while (!token_cursor->status) {
          if ((tid = grn_token_cursor_next(ctx, token_cursor))) {
            if (!grn_hash_add(ctx, new, &tid, sizeof(grn_id), (void **) &u,
                              NULL)) {
              break;
            }
            if (!*u) {
              if (!(*u = grn_ii_updspec_open(ctx, rid, section))) {
                GRN_LOG(ctx, GRN_LOG_ALERT,
                        "grn_ii_updspec_open on grn_ii_update failed!");
                grn_token_cursor_close(ctx, token_cursor);
                grn_hash_close(ctx, new);
                rc = GRN_NO_MEMORY_AVAILABLE;
                goto exit;
              }
            }
            if (grn_ii_updspec_add(ctx, *u, token_cursor->pos, v->weight)) {
              GRN_LOG(ctx, GRN_LOG_ALERT,
                      "grn_ii_updspec_add on grn_ii_update failed!");
              grn_token_cursor_close(ctx, token_cursor);
              grn_hash_close(ctx, new);
              rc = GRN_NO_MEMORY_AVAILABLE;
              goto exit;
            }
          }
        }
        grn_token_cursor_close(ctx, token_cursor);
      }
    }
    if (!GRN_HASH_SIZE(new)) {
      grn_hash_close(ctx, new);
      new = NULL;
    }
  } else {
    new = NULL;
  }
  if (oldvalues) {
    old = grn_hash_create(ctx, NULL, sizeof(grn_id), sizeof(grn_ii_updspec *),
                          GRN_HASH_TINY);
    if (!old) {
      GRN_LOG(ctx, GRN_LOG_ALERT,
              "grn_hash_create(ctx, NULL, old) on grn_ii_update failed!");
      if (new) { grn_hash_close(ctx, new); }
      rc = GRN_NO_MEMORY_AVAILABLE;
      goto exit;
    }
    for (j = oldvalues->n_values, v = oldvalues->values; j; j--, v++) {
      if ((token_cursor = grn_token_cursor_open(ctx, lexicon, v->str,
                                                v->str_len, GRN_TOKEN_DEL,
                                                token_flags))) {
        while (!token_cursor->status) {
          if ((tid = grn_token_cursor_next(ctx, token_cursor))) {
            if (!grn_hash_add(ctx, old, &tid, sizeof(grn_id), (void **) &u,
                              NULL)) {
              break;
            }
            if (!*u) {
              if (!(*u = grn_ii_updspec_open(ctx, rid, section))) {
                GRN_LOG(ctx, GRN_LOG_ALERT,
                        "grn_ii_updspec_open on grn_ii_update failed!");
                grn_token_cursor_close(ctx, token_cursor);
                if (new) { grn_hash_close(ctx, new); };
                grn_hash_close(ctx, old);
                rc = GRN_NO_MEMORY_AVAILABLE;
                goto exit;
              }
            }
            if (grn_ii_updspec_add(ctx, *u, token_cursor->pos, v->weight)) {
              GRN_LOG(ctx, GRN_LOG_ALERT,
                      "grn_ii_updspec_add on grn_ii_update failed!");
              grn_token_cursor_close(ctx, token_cursor);
              if (new) { grn_hash_close(ctx, new); };
              grn_hash_close(ctx, old);
              rc = GRN_NO_MEMORY_AVAILABLE;
              goto exit;
            }
          }
        }
        grn_token_cursor_close(ctx, token_cursor);
      }
    }
  } else {
    old = NULL;
  }
  if (old) {
    grn_id eid;
    GRN_HASH_EACH(ctx, old, id, &tp, NULL, &u, {
      if (new && (eid = grn_hash_get(ctx, new, tp, sizeof(grn_id),
                                     (void **) &un))) {
        if (!grn_ii_updspec_cmp(*u, *un)) {
          grn_ii_updspec_close(ctx, *un);
          grn_hash_delete_by_id(ctx, new, eid, NULL);
        }
      } else {
        grn_rc r;
        r = grn_ii_delete_one(ctx, ii, *tp, *u, new);
        if (r) {
          rc = r;
        }
      }
      grn_ii_updspec_close(ctx, *u);
    });
    grn_hash_close(ctx, old);
  }
  if (new) {
    GRN_HASH_EACH(ctx, new, id, &tp, NULL, &u, {
      grn_rc r;
      if ((r = grn_ii_update_one(ctx, ii, *tp, *u, new))) { rc = r; }
      grn_ii_updspec_close(ctx, *u);
    });
    grn_hash_close(ctx, new);
  } else {
    if (!section) {
      /* todo: delete key when all sections deleted */
    }
  }
exit :
  return rc;
}
#endif /* USE_VGRAM */

static grn_rc
grn_vector2updspecs(grn_ctx *ctx, grn_ii *ii, grn_id rid, unsigned int section,
                    grn_obj *in, grn_obj *out, grn_tokenize_mode mode,
                    grn_obj *posting)
{
  int j;
  grn_id tid;
  grn_section *v;
  grn_token_cursor *token_cursor;
  grn_ii_updspec **u;
  grn_hash *h = (grn_hash *)out;
  grn_obj *lexicon = ii->lexicon;
  if (in->u.v.body) {
    const char *head = GRN_BULK_HEAD(in->u.v.body);
    for (j = in->u.v.n_sections, v = in->u.v.sections; j; j--, v++) {
      unsigned int token_flags = 0;
      if (v->length &&
          (token_cursor = grn_token_cursor_open(ctx, lexicon, head + v->offset,
                                                v->length, mode,
                                                token_flags))) {
        while (!token_cursor->status) {
          if ((tid = grn_token_cursor_next(ctx, token_cursor))) {
            if (posting) { GRN_RECORD_PUT(ctx, posting, tid); }
            if (!grn_hash_add(ctx, h, &tid, sizeof(grn_id), (void **) &u,
                              NULL)) {
              break;
            }
            if (!*u) {
              if (!(*u = grn_ii_updspec_open(ctx, rid, section))) {
                GRN_DEFINE_NAME(ii);
                MERR("[ii][update][spec] failed to create an update spec: "
                     "<%.*s>: "
                     "record:<%u>:<%u>, token:<%u>:<%d>:<%f>",
                     name_size, name,
                     rid, section,
                     tid, token_cursor->pos, v->weight);
                grn_token_cursor_close(ctx, token_cursor);
                return ctx->rc;
              }
            }
            if (grn_ii_updspec_add(ctx, *u, token_cursor->pos, v->weight)) {
              GRN_DEFINE_NAME(ii);
              MERR("[ii][update][spec] failed to add to update spec: "
                   "<%.*s>: "
                   "record:<%u>:<%u>, token:<%u>:<%d>:<%f>",
                   name_size, name,
                   rid, section,
                   tid, token_cursor->pos, v->weight);
              grn_token_cursor_close(ctx, token_cursor);
              return ctx->rc;
            }
          }
        }
        grn_token_cursor_close(ctx, token_cursor);
      }
    }
  }
  return ctx->rc;
}

static grn_rc
grn_uvector2updspecs_data(grn_ctx *ctx, grn_ii *ii, grn_id rid,
                          unsigned int section, grn_obj *in, grn_obj *out,
                          grn_tokenize_mode mode, grn_obj *posting)
{
  grn_rc rc = GRN_SUCCESS;
  grn_hash *h = (grn_hash *)out;
  grn_obj *lexicon = ii->lexicon;
  grn_obj *tokenizer;
  bool need_cast;
  grn_obj element_buffer;
  grn_obj casted_element_buffer;
  int i, n;
  unsigned int element_size;

  tokenizer = grn_obj_get_info(ctx, lexicon, GRN_INFO_DEFAULT_TOKENIZER,
                               NULL);
  need_cast = (!tokenizer && lexicon->header.domain != in->header.domain);
  if (need_cast) {
    GRN_VALUE_FIX_SIZE_INIT(&element_buffer,
                            0,
                            in->header.domain);
    GRN_VALUE_FIX_SIZE_INIT(&casted_element_buffer,
                            GRN_OBJ_VECTOR,
                            lexicon->header.domain);
  } else {
    GRN_VOID_INIT(&element_buffer);
    GRN_VOID_INIT(&casted_element_buffer);
  }

  n = grn_uvector_size(ctx, in);
  element_size = grn_uvector_element_size(ctx, in);
  for (i = 0; i < n; i++) {
    grn_token_cursor *token_cursor;
    unsigned int token_flags = 0;
    const char *element;

    element = GRN_BULK_HEAD(in) + (element_size * i);
    if (need_cast) {
      GRN_BULK_REWIND(&element_buffer);
      GRN_BULK_REWIND(&casted_element_buffer);
      grn_bulk_write(ctx, &element_buffer, element, element_size);
      grn_rc cast_rc = grn_obj_cast(ctx,
                                    &element_buffer,
                                    &casted_element_buffer,
                                    true);
      if (cast_rc != GRN_SUCCESS) {
        GRN_DEFINE_NAME(ii);
        {
          grn_obj *domain = grn_ctx_at(ctx,
                                       casted_element_buffer.header.domain);
          char domain_name[GRN_TABLE_MAX_KEY_SIZE];
          int domain_name_size;
          domain_name_size = grn_obj_name(ctx,
                                          domain,
                                          domain_name,
                                          GRN_TABLE_MAX_KEY_SIZE);
          grn_obj inspected_element;
          GRN_TEXT_INIT(&inspected_element, 0);
          grn_inspect(ctx, &inspected_element, &element_buffer);
          GRN_LOG(ctx,
                  GRN_LOG_WARNING,
                  "[ii][updspec][uvector][data][%*.s] "
                  "failed to cast to <%.*s>: <%.*s>",
                  name_size, name,
                  domain_name_size, domain_name,
                  (int)GRN_TEXT_LEN(&inspected_element),
                  GRN_TEXT_VALUE(&inspected_element));
          GRN_OBJ_FIN(ctx, &inspected_element);
        }
      }
      element = GRN_BULK_HEAD(&casted_element_buffer);
      element_size = GRN_BULK_VSIZE(&casted_element_buffer);
    }
    token_cursor = grn_token_cursor_open(ctx, lexicon,
                                         element, element_size,
                                         mode, token_flags);
    if (!token_cursor) {
      continue;
    }

    while (!token_cursor->status) {
      grn_id tid;
      if ((tid = grn_token_cursor_next(ctx, token_cursor))) {
        grn_ii_updspec **u;
        int pos;

        if (posting) { GRN_RECORD_PUT(ctx, posting, tid); }
        if (!grn_hash_add(ctx, h, &tid, sizeof(grn_id), (void **)&u, NULL)) {
          break;
        }
        if (!*u) {
          if (!(*u = grn_ii_updspec_open(ctx, rid, section))) {
            GRN_LOG(ctx, GRN_LOG_ALERT,
                    "grn_ii_updspec_open on grn_uvector2updspecs_data failed!");
            grn_token_cursor_close(ctx, token_cursor);
            rc = GRN_NO_MEMORY_AVAILABLE;
            goto exit;
          }
        }
        if (tokenizer) {
          pos = token_cursor->pos;
        } else {
          pos = i;
        }
        if (grn_ii_updspec_add(ctx, *u, pos, 0)) {
          GRN_LOG(ctx, GRN_LOG_ALERT,
                  "grn_ii_updspec_add on grn_uvector2updspecs failed!");
          grn_token_cursor_close(ctx, token_cursor);
          rc = GRN_NO_MEMORY_AVAILABLE;
          goto exit;
        }
      }
    }

    grn_token_cursor_close(ctx, token_cursor);
  }

exit :
  GRN_OBJ_FIN(ctx, &element_buffer);
  GRN_OBJ_FIN(ctx, &casted_element_buffer);

  return rc;
}

static grn_rc
grn_uvector2updspecs_id(grn_ctx *ctx, grn_ii *ii, grn_id rid,
                        unsigned int section, grn_obj *in, grn_obj *out)
{
  int i, n;
  grn_ii_updspec **u;
  grn_hash *h = (grn_hash *)out;

  n = grn_vector_size(ctx, in);
  for (i = 0; i < n; i++) {
    grn_id id;
    uint32_t weight;

    id = grn_uvector_get_element(ctx, in, i, &weight);
    if (!grn_hash_add(ctx, h, &id, sizeof(grn_id), (void **)&u, NULL)) {
      break;
    }
    if (!*u) {
      if (!(*u = grn_ii_updspec_open(ctx, rid, section))) {
        GRN_LOG(ctx, GRN_LOG_ALERT,
                "grn_ii_updspec_open on grn_ii_update failed!");
        return GRN_NO_MEMORY_AVAILABLE;
      }
    }
    if (grn_ii_updspec_add(ctx, *u, i, weight)) {
      GRN_LOG(ctx, GRN_LOG_ALERT,
              "grn_ii_updspec_add on grn_ii_update failed!");
      return GRN_NO_MEMORY_AVAILABLE;
    }
  }
  return GRN_SUCCESS;
}

static grn_rc
grn_uvector2updspecs(grn_ctx *ctx, grn_ii *ii, grn_id rid,
                     unsigned int section, grn_obj *in, grn_obj *out,
                     grn_tokenize_mode mode, grn_obj *posting)
{
  if (grn_type_id_is_builtin(ctx, in->header.domain)) {
    return grn_uvector2updspecs_data(ctx, ii, rid, section, in, out,
                                     mode, posting);
  } else {
    return grn_uvector2updspecs_id(ctx, ii, rid, section, in, out);
  }
}

grn_rc
grn_ii_column_update(grn_ctx *ctx, grn_ii *ii, grn_id rid, unsigned int section,
                     grn_obj *oldvalue, grn_obj *newvalue, grn_obj *posting)
{
  grn_id *tp;
  grn_bool do_grn_ii_updspec_cmp = GRN_TRUE;
  grn_ii_updspec **u, **un;
  grn_obj *old_, *old = oldvalue, *new_, *new = newvalue, oldv, newv;
  grn_obj buf, *post = NULL;

  if (!ii) {
    ERR(GRN_INVALID_ARGUMENT, "[ii][column][update] ii is NULL");
    return ctx->rc;
  }
  if (!ii->lexicon) {
    ERR(GRN_INVALID_ARGUMENT, "[ii][column][update] lexicon is NULL");
    return ctx->rc;
  }
  if (rid == GRN_ID_NIL) {
    GRN_DEFINE_NAME(ii);
    ERR(GRN_INVALID_ARGUMENT,
        "[ii][column][update] record ID is nil: <%.*s>",
        name_size, name);
    return ctx->rc;
  }
  if (old || new) {
    grn_bool is_text_vector_index = GRN_TRUE;
    if (old) {
      if (!(old->header.type == GRN_VECTOR &&
            grn_type_id_is_text_family(ctx, old->header.domain))) {
        is_text_vector_index = GRN_FALSE;
      }
    }
    if (new) {
      if (!(new->header.type == GRN_VECTOR &&
            grn_type_id_is_text_family(ctx, new->header.domain))) {
        is_text_vector_index = GRN_FALSE;
      }
    }
    if (is_text_vector_index) {
      grn_obj *tokenizer;
      grn_table_get_info(ctx, ii->lexicon, NULL, NULL, &tokenizer, NULL, NULL);
      if (tokenizer) {
        grn_obj old_elem, new_elem;
        unsigned int i, max_n;
        unsigned int old_n = 0, new_n = 0;
        if (old) {
          old_n = grn_vector_size(ctx, old);
          GRN_OBJ_INIT(&old_elem, GRN_BULK, GRN_OBJ_DO_SHALLOW_COPY, old->header.domain);
        }
        if (new) {
          new_n = grn_vector_size(ctx, new);
          GRN_OBJ_INIT(&new_elem, GRN_BULK, GRN_OBJ_DO_SHALLOW_COPY, new->header.domain);
        }
        max_n = (old_n > new_n) ? old_n : new_n;
        for (i = 0; i < max_n; i++) {
          grn_rc rc;
          grn_obj *old_p = NULL, *new_p = NULL;
          if (i < old_n) {
            const char *value;
            unsigned int size;
            size = grn_vector_get_element(ctx, old, i, &value, NULL, NULL);
            GRN_TEXT_SET_REF(&old_elem, value, size);
            old_p = &old_elem;
          }
          if (i < new_n) {
            const char *value;
            unsigned int size;
            size = grn_vector_get_element(ctx, new, i, &value, NULL, NULL);
            GRN_TEXT_SET_REF(&new_elem, value, size);
            new_p = &new_elem;
          }
          rc = grn_ii_column_update(ctx, ii, rid, section + i, old_p, new_p, posting);
          if (rc != GRN_SUCCESS) {
            break;
          }
        }
        if (old) {
          GRN_OBJ_FIN(ctx, &old_elem);
        }
        if (new) {
          GRN_OBJ_FIN(ctx, &new_elem);
        }
        return ctx->rc;
      }
    }
  }
  if (posting) {
    GRN_RECORD_INIT(&buf, GRN_OBJ_VECTOR, grn_obj_id(ctx, ii->lexicon));
    post = &buf;
  }
  if (grn_io_lock(ctx, ii->seg, grn_lock_timeout)) { return ctx->rc; }
  if (new) {
    unsigned char type = (ii->obj.header.domain == new->header.domain)
      ? GRN_UVECTOR
      : new->header.type;
    switch (type) {
    case GRN_BULK :
      {
        if (grn_bulk_is_zero(ctx, new)) {
          do_grn_ii_updspec_cmp = GRN_FALSE;
        }
        new_ = new;
        GRN_OBJ_INIT(&newv, GRN_VECTOR, GRN_OBJ_DO_SHALLOW_COPY, GRN_DB_TEXT);
        newv.u.v.body = new;
        new = &newv;
        grn_vector_delimit(ctx, new, 0, GRN_ID_NIL);
        if (new_ != newvalue) { grn_obj_close(ctx, new_); }
      }
      /* fallthru */
    case GRN_VECTOR :
      new_ = new;
      new = (grn_obj *)grn_hash_create(ctx, NULL, sizeof(grn_id),
                                       sizeof(grn_ii_updspec *),
                                       GRN_HASH_TINY);
      if (!new) {
        GRN_DEFINE_NAME(ii);
        MERR("[ii][column][update][new][vector] failed to create a hash table: "
             "<%.*s>: ",
             name_size, name);
      } else {
        grn_vector2updspecs(ctx, ii, rid, section, new_, new,
                            GRN_TOKEN_ADD, post);
      }
      if (new_ != newvalue) { grn_obj_close(ctx, new_); }
      if (ctx->rc != GRN_SUCCESS) { goto exit; }
      break;
    case GRN_UVECTOR :
      new_ = new;
      new = (grn_obj *)grn_hash_create(ctx, NULL, sizeof(grn_id),
                                       sizeof(grn_ii_updspec *),
                                       GRN_HASH_TINY);
      if (!new) {
        GRN_DEFINE_NAME(ii);
        MERR("[ii][column][update][new][uvector] failed to create a hash table: "
             "<%.*s>: ",
             name_size, name);
      } else {
        if (new_->header.type == GRN_UVECTOR) {
          grn_uvector2updspecs(ctx, ii, rid, section, new_, new,
                               GRN_TOKEN_ADD, post);
        } else {
          grn_obj uvector;
          uint32_t weight = 0;
          GRN_VALUE_FIX_SIZE_INIT(&uvector, GRN_OBJ_VECTOR,
                                  new_->header.domain);
          if (new_->header.impl_flags & GRN_OBJ_WITH_WEIGHT) {
            uvector.header.impl_flags |= GRN_OBJ_WITH_WEIGHT;
          }
          grn_uvector_add_element(ctx, &uvector, GRN_RECORD_VALUE(new_),
                                  weight);
          grn_uvector2updspecs(ctx, ii, rid, section, &uvector, new,
                               GRN_TOKEN_ADD, post);
          GRN_OBJ_FIN(ctx, &uvector);
        }
      }
      if (new_ != newvalue) { grn_obj_close(ctx, new_); }
      if (ctx->rc != GRN_SUCCESS) { goto exit; }
      break;
    case GRN_TABLE_HASH_KEY :
      break;
    default :
      {
        GRN_DEFINE_NAME(ii);
        ERR(GRN_INVALID_ARGUMENT,
            "[ii][column][update][new] invalid object: "
            "<%.*s>: "
            "<%s>(%#x)",
            name_size, name,
            grn_obj_type_to_string(type),
            type);
      }
      goto exit;
    }
  }
  if (posting) {
    grn_ii_updspec *u_;
    uint32_t offset = 0;
    grn_id tid_ = 0, gap, tid, *tpe;
    grn_table_sort_optarg arg = {
      GRN_TABLE_SORT_ASC|GRN_TABLE_SORT_AS_NUMBER|GRN_TABLE_SORT_AS_UNSIGNED,
      NULL,
      NULL,
      NULL,
      0,
    };
    grn_array *sorted = grn_array_create(ctx, NULL, sizeof(grn_id), 0);
    grn_hash_sort(ctx, (grn_hash *)new, -1, sorted, &arg);
    GRN_TEXT_PUT(ctx, posting, ((grn_hash *)new)->n_entries, sizeof(uint32_t));
    GRN_ARRAY_EACH(ctx, sorted, 0, 0, id, &tp, {
      grn_hash_get_key(ctx, (grn_hash *)new, *tp, &tid, sizeof(grn_id));
      gap = tid - tid_;
      GRN_TEXT_PUT(ctx, posting, &gap, sizeof(grn_id));
      tid_ = tid;
    });
    GRN_ARRAY_EACH(ctx, sorted, 0, 0, id, &tp, {
      grn_hash_get_value(ctx, (grn_hash *)new, *tp, &u_);
      u_->offset = offset++;
      GRN_TEXT_PUT(ctx, posting, &u_->tf, sizeof(int32_t));
    });
    tpe = (grn_id *)GRN_BULK_CURR(post);
    for (tp = (grn_id *)GRN_BULK_HEAD(post); tp < tpe; tp++) {
      grn_hash_get(ctx, (grn_hash *)new, (void *)tp, sizeof(grn_id),
                   (void **)&u);
      GRN_TEXT_PUT(ctx, posting, &(*u)->offset, sizeof(int32_t));
    }
    GRN_OBJ_FIN(ctx, post);
    grn_array_close(ctx, sorted);
  }

  if (old) {
    unsigned char type = (ii->obj.header.domain == old->header.domain)
      ? GRN_UVECTOR
      : old->header.type;
    switch (type) {
    case GRN_BULK :
      {
        //        const char *str = GRN_BULK_HEAD(old);
        //        unsigned int str_len = GRN_BULK_VSIZE(old);
        old_ = old;
        GRN_OBJ_INIT(&oldv, GRN_VECTOR, GRN_OBJ_DO_SHALLOW_COPY, GRN_DB_TEXT);
        oldv.u.v.body = old;
        old = &oldv;
        grn_vector_delimit(ctx, old, 0, GRN_ID_NIL);
        if (old_ != oldvalue) { grn_obj_close(ctx, old_); }
      }
      /* fallthru */
    case GRN_VECTOR :
      old_ = old;
      old = (grn_obj *)grn_hash_create(ctx, NULL, sizeof(grn_id),
                                       sizeof(grn_ii_updspec *),
                                       GRN_HASH_TINY);
      if (!old) {
        GRN_DEFINE_NAME(ii);
        MERR("[ii][column][update][old][vector] failed to create a hash table: "
             "<%.*s>: ",
             name_size, name);
      } else {
        grn_vector2updspecs(ctx, ii, rid, section, old_, old,
                            GRN_TOKEN_DEL, NULL);
      }
      if (old_ != oldvalue) { grn_obj_close(ctx, old_); }
      if (ctx->rc != GRN_SUCCESS) { goto exit; }
      break;
    case GRN_UVECTOR :
      old_ = old;
      old = (grn_obj *)grn_hash_create(ctx, NULL, sizeof(grn_id),
                                       sizeof(grn_ii_updspec *),
                                       GRN_HASH_TINY);
      if (!old) {
        GRN_DEFINE_NAME(ii);
        MERR("[ii][column][update][old][uvector] failed to create a hash table: "
             "<%.*s>: ",
             name_size, name);
      } else {
        if (old_->header.type == GRN_UVECTOR) {
          grn_uvector2updspecs(ctx, ii, rid, section, old_, old,
                               GRN_TOKEN_DEL, NULL);
        } else {
          grn_obj uvector;
          uint32_t weight = 0;
          GRN_VALUE_FIX_SIZE_INIT(&uvector, GRN_OBJ_VECTOR,
                                  old_->header.domain);
          if (old_->header.impl_flags & GRN_OBJ_WITH_WEIGHT) {
            uvector.header.impl_flags |= GRN_OBJ_WITH_WEIGHT;
          }
          grn_uvector_add_element(ctx, &uvector, GRN_RECORD_VALUE(old_),
                                  weight);
          grn_uvector2updspecs(ctx, ii, rid, section, &uvector, old,
                               GRN_TOKEN_DEL, NULL);
          GRN_OBJ_FIN(ctx, &uvector);
        }
      }
      if (old_ != oldvalue) { grn_obj_close(ctx, old_); }
      if (ctx->rc != GRN_SUCCESS) { goto exit; }
      break;
    case GRN_TABLE_HASH_KEY :
      break;
    default :
      {
        GRN_DEFINE_NAME(ii);
        ERR(GRN_INVALID_ARGUMENT,
            "[ii][column][update][old] invalid object: "
            "<%.*s>: "
            "<%s>(%#x)",
            name_size, name,
            grn_obj_type_to_string(type),
            type);
      }
      goto exit;
    }
  }

  if (old) {
    grn_id eid;
    grn_hash *o = (grn_hash *)old;
    grn_hash *n = (grn_hash *)new;
    GRN_HASH_EACH(ctx, o, id, &tp, NULL, &u, {
      if (n && (eid = grn_hash_get(ctx, n, tp, sizeof(grn_id),
                                   (void **) &un))) {
        if (do_grn_ii_updspec_cmp && !grn_ii_updspec_cmp(*u, *un)) {
          grn_ii_updspec_close(ctx, *un);
          grn_hash_delete_by_id(ctx, n, eid, NULL);
        }
      } else {
        grn_ii_delete_one(ctx, ii, *tp, *u, n);
      }
      if (ctx->rc != GRN_SUCCESS) {
        break;
      }
    });
  }
  if (new) {
    grn_hash *n = (grn_hash *)new;
    GRN_HASH_EACH(ctx, n, id, &tp, NULL, &u, {
      grn_ii_update_one(ctx, ii, *tp, *u, n);
      if (ctx->rc != GRN_SUCCESS) {
        break;
      }
    });
  } else {
    if (!section) {
      /* todo: delete key when all sections deleted */
    }
  }
exit :
  grn_io_unlock(ctx, ii->seg);
  if (old && old->header.type == GRN_TABLE_HASH_KEY) {
    grn_hash *o = (grn_hash *)old;
    GRN_HASH_EACH(ctx, o, id, &tp, NULL, &u, {
      grn_ii_updspec_close(ctx, *u);
    });
    if (old != oldvalue) { grn_obj_close(ctx, old); }
  }
  if (new && new->header.type == GRN_TABLE_HASH_KEY) {
    grn_hash *n = (grn_hash *)new;
    GRN_HASH_EACH(ctx, n, id, &tp, NULL, &u, {
      grn_ii_updspec_close(ctx, *u);
    });
    if (new != newvalue) { grn_obj_close(ctx, new); }
  }
  return ctx->rc;
}

/* token_info */

typedef struct {
  cursor_heap *cursors;
  uint32_t offset;
  int32_t pos;
  uint32_t size;
  int ntoken;
  grn_posting *p;
  uint32_t phrase_group_id;
  uint32_t phrase_id;
  uint32_t n_tokens_in_phrase;
  bool must_last;
} token_info;

#define EX_NONE   0
#define EX_PREFIX 1
#define EX_SUFFIX 2
#define EX_BOTH   3
#define EX_FUZZY  4

struct _btr_node {
  struct _btr_node *car;
  struct _btr_node *cdr;
  token_info *ti;
};

typedef struct _btr_node btr_node;

typedef struct {
  int n;
  token_info *min;
  token_info *max;
  btr_node *root;
  btr_node *nodes;
  uint32_t n_must_lasts;
} btr;

typedef enum {
  GRN_WV_NONE = 0,
  GRN_WV_STATIC,
  GRN_WV_DYNAMIC,
  GRN_WV_CONSTANT
} grn_wv_mode;

typedef struct {
  uint32_t n_phrases;
  btr *btree;
} phrase_group;

typedef struct {
  grn_ii *ii;
  grn_obj *lexicon;
  const char *query;
  unsigned int query_len;
  grn_hash *result_set;
  grn_operator op;
  grn_select_optarg *optarg;
  grn_operator mode;
  grn_wv_mode wv_mode;
  grn_scorer_score_func *score_func;
  grn_scorer_matched_record record;
  grn_id previous_min;
  grn_id current_min;
  bool set_min_enable_for_and_query;
  grn_fuzzy_search_optarg *fuzzy_search_optarg;
  grn_obj *query_options;
  bool only_skip_token;
  token_info **token_infos;
  uint32_t n_token_infos;
  uint32_t n_phrase_groups;
  phrase_group *phrase_groups;
  uint32_t n_phrases;
  token_info *token_info;
  btr *bt;
  int max_interval;
  int additional_last_interval;
  grn_obj *max_element_intervals;
  btr *check_element_intervals_btree;
  int32_t pos;
  grn_id rid;
  uint32_t sid;
  grn_id next_rid;
  uint32_t next_sid;
  bool may_match;
  int32_t start_pos;
  int32_t end_pos;
  int32_t total_score;
  uint32_t n_occurrences;
} grn_ii_select_data;

static grn_inline grn_token_cursor *
grn_ii_select_data_open_token_cursor(grn_ctx *ctx,
                                     grn_ii_select_data *data,
                                     const char *text,
                                     size_t text_length,
                                     grn_tokenize_mode mode)
{
  uint32_t token_flags = GRN_TOKEN_CURSOR_ENABLE_TOKENIZED_DELIMITER;
  grn_token_cursor *token_cursor = grn_token_cursor_open(ctx,
                                                         data->lexicon,
                                                         text,
                                                         text_length,
                                                         mode,
                                                         token_flags);
  if (!token_cursor) {
    return NULL;
  }
  if (data->query_options) {
    grn_token_cursor_set_query_options(ctx, token_cursor, data->query_options);
    if (ctx->rc != GRN_SUCCESS) {
      grn_token_cursor_close(ctx, token_cursor);
      return NULL;
    }
  }
  return token_cursor;
}

grn_inline static void
token_info_expand_both(grn_ctx *ctx, grn_ii_select_data *data,
                       const char *key, unsigned int key_size, token_info *ti)
{
  int s = 0;
  grn_hash *h, *g;
  uint32_t *offset2;
  grn_hash_cursor *c;
  grn_id *tp, *tq;
  if ((h = grn_hash_create(ctx, NULL, sizeof(grn_id), 0, 0))) {
    grn_operator mode = GRN_OP_PREFIX;
    if (data->lexicon->header.type == GRN_TABLE_HASH_KEY) {
      mode = GRN_OP_EXACT;
    }
    grn_table_search(ctx, data->lexicon, key, key_size,
                     mode, (grn_obj *)h, GRN_OP_OR);
    if (GRN_HASH_SIZE(h)) {
      if ((ti->cursors = cursor_heap_open(ctx, GRN_HASH_SIZE(h) + 256))) {
        if ((c = grn_hash_cursor_open(ctx, h, NULL, 0, NULL, 0, 0, -1, 0))) {
          uint32_t key2_size;
          const char *key2;
          while (grn_hash_cursor_next(ctx, c)) {
            grn_hash_cursor_get_key(ctx, c, (void **) &tp);
            key2 = _grn_table_key(ctx, data->lexicon, *tp, &key2_size);
            if (!key2) { break; }
            if ((data->lexicon->header.type != GRN_TABLE_PAT_KEY) ||
                !(data->lexicon->header.flags & GRN_OBJ_KEY_WITH_SIS) ||
                key2_size <= 2) { // todo: refine
              if ((s = grn_ii_estimate_size(ctx, data->ii, *tp))) {
                cursor_heap_push(ctx,
                                 ti->cursors,
                                 data->ii,
                                 *tp,
                                 0,
                                 0,
                                 data->previous_min);
                ti->ntoken++;
                ti->size += s;
              }
            } else {
              if ((g = grn_hash_create(ctx, NULL, sizeof(grn_id), 0,
                                       GRN_HASH_TINY))) {
                grn_pat_suffix_search(ctx,
                                      (grn_pat *)(data->lexicon),
                                      key2,
                                      key2_size,
                                      g);
                GRN_HASH_EACH(ctx, g, id, &tq, NULL, &offset2, {
                  if ((s = grn_ii_estimate_size(ctx, data->ii, *tq))) {
                    cursor_heap_push(ctx,
                                     ti->cursors,
                                     data->ii,
                                     *tq,
                                     /* *offset2 */ 0,
                                     0,
                                     data->previous_min);
                    ti->ntoken++;
                    ti->size += s;
                  }
                });
                grn_hash_close(ctx, g);
              }
            }
          }
          grn_hash_cursor_close(ctx, c);
        }
      }
    }
    grn_hash_close(ctx, h);
  }
}

grn_inline static grn_rc
token_info_close(grn_ctx *ctx, token_info *ti)
{
  cursor_heap_close(ctx, ti->cursors);
  GRN_FREE(ti);
  return GRN_SUCCESS;
}

grn_inline static token_info *
token_info_open(grn_ctx *ctx,
                grn_ii_select_data *data,
                const char *key,
                unsigned int key_size,
                uint32_t offset,
                int mode)
{
  uint32_t s = 0;
  grn_hash *h;
  token_info *ti;
  grn_id tid;
  grn_id *tp;
  if (!key) { return NULL; }
  if (!(ti = GRN_CALLOC(sizeof(token_info)))) { return NULL; }
  ti->cursors = NULL;
  ti->size = 0;
  ti->ntoken = 0;
  ti->offset = offset;
  ti->phrase_id = 0;
  ti->must_last = false;
  switch (mode) {
  case EX_BOTH :
    token_info_expand_both(ctx, data, key, key_size, ti);
    break;
  case EX_NONE :
    if ((tid = grn_table_get(ctx, data->lexicon, key, key_size)) &&
        (s = grn_ii_estimate_size(ctx, data->ii, tid)) &&
        (ti->cursors = cursor_heap_open(ctx, 1))) {
      cursor_heap_push(ctx,
                       ti->cursors,
                       data->ii,
                       tid,
                       0,
                       0,
                       data->previous_min);
      ti->ntoken++;
      ti->size = s;
    }
    break;
  case EX_PREFIX :
    if ((h = grn_hash_create(ctx, NULL, sizeof(grn_id), 0, 0))) {
      grn_operator mode = GRN_OP_PREFIX;
      if (data->lexicon->header.type == GRN_TABLE_HASH_KEY) {
        mode = GRN_OP_EXACT;
      }
      grn_table_search(ctx, data->lexicon, key, key_size,
                       mode, (grn_obj *)h, GRN_OP_OR);
      if (GRN_HASH_SIZE(h)) {
        if ((ti->cursors = cursor_heap_open(ctx, GRN_HASH_SIZE(h)))) {
          GRN_HASH_EACH(ctx, h, id, &tp, NULL, NULL, {
            if ((s = grn_ii_estimate_size(ctx, data->ii, *tp))) {
              cursor_heap_push(ctx,
                               ti->cursors,
                               data->ii,
                               *tp,
                               0,
                               0,
                               data->previous_min);
              ti->ntoken++;
              ti->size += s;
            }
          });
        }
      }
      grn_hash_close(ctx, h);
    }
    break;
  case EX_SUFFIX :
    if ((h = grn_hash_create(ctx, NULL, sizeof(grn_id), 0, 0))) {
      grn_operator mode = GRN_OP_SUFFIX;
      if (data->lexicon->header.type == GRN_TABLE_HASH_KEY) {
        mode = GRN_OP_EXACT;
      }
      grn_table_search(ctx, data->lexicon, key, key_size,
                       mode, (grn_obj *)h, GRN_OP_OR);
      if (GRN_HASH_SIZE(h)) {
        if ((ti->cursors = cursor_heap_open(ctx, GRN_HASH_SIZE(h)))) {
          uint32_t *offset2;
          GRN_HASH_EACH(ctx, h, id, &tp, NULL, &offset2, {
            if ((s = grn_ii_estimate_size(ctx, data->ii, *tp))) {
              cursor_heap_push(ctx,
                               ti->cursors,
                               data->ii,
                               *tp,
                               /* *offset2 */ 0,
                               0,
                               data->previous_min);
              ti->ntoken++;
              ti->size += s;
            }
          });
        }
      }
      grn_hash_close(ctx, h);
    }
    break;
  case EX_FUZZY :
    if ((h = (grn_hash *)grn_table_create(ctx, NULL, 0, NULL,
        GRN_OBJ_TABLE_HASH_KEY|GRN_OBJ_WITH_SUBREC,
        grn_ctx_at(ctx, GRN_DB_UINT32), NULL))) {
      grn_table_fuzzy_search(ctx,
                             data->lexicon,
                             key,
                             key_size,
                             data->fuzzy_search_optarg,
                             (grn_obj *)h,
                             GRN_OP_OR);
      if (GRN_HASH_SIZE(h)) {
        if ((ti->cursors = cursor_heap_open(ctx, GRN_HASH_SIZE(h)))) {
          grn_rset_recinfo *ri;
          GRN_HASH_EACH(ctx, h, id, &tp, NULL, (void **)&ri, {
            if ((s = grn_ii_estimate_size(ctx, data->ii, *tp))) {
              cursor_heap_push(ctx,
                               ti->cursors,
                               data->ii,
                               *tp,
                               0,
                               ri->score - 1,
                               data->previous_min);
              ti->ntoken++;
              ti->size += s;
            }
          });
        }
      }
      grn_obj_close(ctx, (grn_obj *)h);
    }
    break;
  }
  if (cursor_heap_push2(ti->cursors)) {
    token_info_close(ctx, ti);
    return NULL;
  }
  {
    grn_ii_cursor *ic;
    if (ti->cursors && (ic = cursor_heap_min(ti->cursors))) {
      grn_posting *p = ic->post;
      ti->pos = p->pos - ti->offset;
      ti->p = p;
    } else {
      token_info_close(ctx, ti);
      ti = NULL;
    }
  }
  return ti;
}

static grn_inline grn_rc
token_info_skip(grn_ctx *ctx, token_info *ti, uint32_t rid, uint32_t sid)
{
  grn_ii_cursor *c;
  grn_posting *p;
  for (;;) {
    if (!(c = cursor_heap_min(ti->cursors))) { return GRN_END_OF_DATA; }
    p = c->post;
    if (p->rid > rid || (p->rid == rid && p->sid >= sid)) { break; }
    cursor_heap_pop(ctx, ti->cursors, rid);
  }
  ti->pos = p->pos - ti->offset;
  ti->p = p;
  return GRN_SUCCESS;
}

static grn_inline grn_rc
token_info_skip_pos(grn_ctx *ctx, token_info *ti, uint32_t rid, uint32_t sid, int32_t pos)
{
  grn_ii_cursor *c;
  grn_posting *p;
  pos += ti->offset;
  for (;;) {
    if (!(c = cursor_heap_min(ti->cursors))) { return GRN_END_OF_DATA; }
    p = c->post;
    if (p->rid != rid || p->sid != sid || (int32_t)(p->pos) >= pos) { break; }
    cursor_heap_pop_pos(ctx, ti->cursors);
  }
  ti->pos = p->pos - ti->offset;
  ti->p = p;
  return GRN_SUCCESS;
}

grn_inline static int
token_compare(const void *a, const void *b)
{
  const token_info *t1 = *((token_info **)a), *t2 = *((token_info **)b);
  if (t1->phrase_group_id == t2->phrase_group_id) {
    if (t1->phrase_id == t2->phrase_id) {
      return t1->size - t2->size;
    } else {
      return t1->phrase_id - t2->phrase_id;
    }
  } else {
    return t1->phrase_group_id - t2->phrase_group_id;
  }
}

#define TOKEN_CANDIDATE_NODE_SIZE 32
#define TOKEN_CANDIDATE_ADJACENT_MAX_SIZE 16
#define TOKEN_CANDIDATE_QUEUE_SIZE 64
#define TOKEN_CANDIDATE_SIZE 16

typedef struct {
  grn_id tid;
  const unsigned char *token;
  uint32_t token_size;
  int32_t pos;
  grn_token_cursor_status status;
  int ef;
  uint32_t estimated_size;
  uint8_t adjacent[TOKEN_CANDIDATE_ADJACENT_MAX_SIZE]; /* Index of adjacent node from top */
  uint8_t n_adjacent;
} token_candidate_node;

typedef struct {
  uint32_t *candidates; /* Standing bits indicate index of token_candidate_node */
  int top;
  int rear;
  int size;
} token_candidate_queue;

typedef struct {
  grn_ii_select_data *select_data;
  token_candidate_node *nodes;
  uint32_t n_nodes;
  uint32_t max_estimated_size;
  uint32_t selected_candidate;
} token_candidate_data;

grn_inline static void
token_candidate_adjacent_set(grn_ctx *ctx, grn_token_cursor *token_cursor,
                             token_candidate_node *top, token_candidate_node *curr)
{
  grn_bool exists_adjacent = GRN_FALSE;
  token_candidate_node *adj;
  for (adj = top; adj < curr; adj++) {
    if (token_cursor->curr <= adj->token + adj->token_size) {
      if (adj->n_adjacent < TOKEN_CANDIDATE_ADJACENT_MAX_SIZE) {
        adj->adjacent[adj->n_adjacent] = curr - top;
        adj->n_adjacent++;
        exists_adjacent = GRN_TRUE;
      }
    }
  }
  if (!exists_adjacent) {
    adj = curr - 1;
    if (adj->n_adjacent < TOKEN_CANDIDATE_ADJACENT_MAX_SIZE) {
      adj->adjacent[adj->n_adjacent] = curr - top;
      adj->n_adjacent++;
    }
  }
}

grn_inline static grn_rc
token_candidate_init(grn_ctx *ctx,
                     token_candidate_data *data,
                     grn_ii_select_data *select_data,
                     grn_token_cursor *token_cursor,
                     grn_id tid,
                     int ef)
{
  data->select_data = select_data;
  size_t size = TOKEN_CANDIDATE_NODE_SIZE;
  data->nodes = GRN_MALLOC(TOKEN_CANDIDATE_NODE_SIZE * sizeof(token_candidate_node));
  if (!data->nodes) {
    return GRN_NO_MEMORY_AVAILABLE;
  }

  token_candidate_node *top = data->nodes;
  token_candidate_node *curr = top;

#define TOKEN_CANDIDATE_NODE_SET() { \
  curr->tid = tid; \
  curr->token = token_cursor->curr; \
  curr->token_size = token_cursor->curr_size; \
  curr->pos = token_cursor->pos; \
  curr->status = token_cursor->status; \
  curr->ef = ef; \
  curr->estimated_size = grn_ii_estimate_size(ctx, select_data->ii, tid); \
  curr->n_adjacent = 0; \
}
  TOKEN_CANDIDATE_NODE_SET();
  GRN_LOG(ctx,
          GRN_LOG_DEBUG,
          "[ii][overlap_token_skip] tid=%u pos=%d estimated_size=%u",
          curr->tid, curr->pos, curr->estimated_size);
  data->max_estimated_size = curr->estimated_size;
  curr++;

  while (token_cursor->status == GRN_TOKEN_CURSOR_DOING) {
    if ((size_t)(curr - top) >= size) {
      token_candidate_node *nodes =
        GRN_REALLOC(data->nodes,
                    (curr - top + TOKEN_CANDIDATE_NODE_SIZE) *
                    sizeof(token_candidate_node));
      if (!nodes) {
        GRN_FREE(data->nodes);
        data->nodes = NULL;
        return GRN_NO_MEMORY_AVAILABLE;
      }
      top = data->nodes;
      curr = top + size;
      size += TOKEN_CANDIDATE_NODE_SIZE;
    }
    tid = grn_token_cursor_next(ctx, token_cursor);
    if (token_cursor->status != GRN_TOKEN_CURSOR_DONE_SKIP) {
      grn_token *token;
      token = grn_token_cursor_get_token(ctx, token_cursor);
      if (grn_token_get_force_prefix_search(ctx, token)) { ef |= EX_PREFIX; }
      TOKEN_CANDIDATE_NODE_SET();
      token_candidate_adjacent_set(ctx, token_cursor, top, curr);
      if (curr->estimated_size > data->max_estimated_size) {
        data->max_estimated_size = curr->estimated_size;
      }
      curr++;
    }
  }
  data->n_nodes = curr - top;
  return GRN_SUCCESS;
#undef TOKEN_CANDIDATE_NODE_SET
}

grn_inline static grn_rc
token_candidate_queue_init(grn_ctx *ctx, token_candidate_queue *q)
{
  q->top = 0;
  q->rear = 0;
  q->size = TOKEN_CANDIDATE_QUEUE_SIZE;

  q->candidates = GRN_MALLOC(TOKEN_CANDIDATE_QUEUE_SIZE * sizeof(uint32_t));
  if (!q->candidates) {
    q->size = 0;
    return GRN_NO_MEMORY_AVAILABLE;
  }
  return GRN_SUCCESS;
}

grn_inline static grn_rc
token_candidate_enqueue(grn_ctx *ctx, token_candidate_queue *q, uint32_t candidate)
{
  if (q->rear >= q->size) {
    if (!(q->candidates =
        GRN_REALLOC(q->candidates,
        (q->rear + TOKEN_CANDIDATE_QUEUE_SIZE) * sizeof(uint32_t)))) {
      q->size = 0;
      return GRN_NO_MEMORY_AVAILABLE;
    }
    q->size += TOKEN_CANDIDATE_QUEUE_SIZE;
  }
  *(q->candidates + q->rear) = candidate;
  q->rear++;
  return GRN_SUCCESS;
}

grn_inline static grn_rc
token_candidate_dequeue(grn_ctx *ctx, token_candidate_queue *q, uint32_t *candidate)
{
  if (q->top == q->rear) {
    return GRN_END_OF_DATA;
  }
  *candidate = *(q->candidates + q->top);
  q->top++;
  return GRN_SUCCESS;
}

grn_inline static void
token_candidate_queue_fin(grn_ctx *ctx, token_candidate_queue *q)
{
  GRN_FREE(q->candidates);
}

grn_inline static token_candidate_node*
token_candidate_last_node(grn_ctx *ctx,
                          token_candidate_data *data,
                          uint32_t candidate,
                          int offset)
{
  int i;
  GRN_BIT_SCAN_REV(candidate, i);
  return data->nodes + i + offset;
}

grn_inline static uint64_t
token_candidate_score(grn_ctx *ctx,
                      token_candidate_data *data,
                      uint32_t candidate,
                      int offset)
{
  int i, last;
  uint64_t score = 0;
  GRN_BIT_SCAN_REV(candidate, last);
  for (i = 0; i <= last; i++) {
    if (candidate & (1 << i)) {
      token_candidate_node *node = data->nodes + i + offset;
      if (node->estimated_size > 0) {
        score += data->max_estimated_size / node->estimated_size;
      }
    }
  }
  return score;
}

grn_inline static grn_rc
token_candidate_select(grn_ctx *ctx,
                       token_candidate_data *data,
                       uint32_t offset,
                       uint32_t limit)
{
  if (offset + limit > (data->n_nodes - 1)) {
    limit = (data->n_nodes - 1) - offset;
  }
  token_candidate_queue q;
  grn_rc rc = token_candidate_queue_init(ctx, &q);
  if (rc != GRN_SUCCESS) {
    return rc;
  }
  rc = token_candidate_enqueue(ctx, &q, 1);
  if (rc != GRN_SUCCESS) {
    goto exit;
  }
  uint32_t candidate;
  uint64_t max_score = 0;
  uint32_t min_n_nodes = 0;
  while (token_candidate_dequeue(ctx, &q, &candidate) != GRN_END_OF_DATA) {
    token_candidate_node *candidate_last_node =
      token_candidate_last_node(ctx, data, candidate, offset);
    int i;
    for (i = 0; i < candidate_last_node->n_adjacent; i++) {
      uint32_t adjacent;
      uint32_t new_candidate;
      uint32_t n_nodes = 0;
      adjacent = candidate_last_node->adjacent[i] - offset;
      if (adjacent > limit) {
        break;
      }
      new_candidate = candidate | (1 << adjacent);
      GET_NUM_BITS(new_candidate, n_nodes);
      if (min_n_nodes > 0 && n_nodes > min_n_nodes + 1) {
        goto exit;
      }
      rc = token_candidate_enqueue(ctx, &q, new_candidate);
      if (rc != GRN_SUCCESS) {
        goto exit;
      }
      if (adjacent == limit) {
        if (min_n_nodes == 0) {
          min_n_nodes = n_nodes;
        }
        if (min_n_nodes <= n_nodes && n_nodes <= min_n_nodes + 1) {
          uint64_t score =
            token_candidate_score(ctx, data, new_candidate, offset);
          if (score > max_score) {
            max_score = score;
            data->selected_candidate = new_candidate;
          }
        }
      }
    }
  }
  rc = GRN_SUCCESS;
exit :
  token_candidate_queue_fin(ctx, &q);
  return rc;
}

grn_inline static grn_rc
token_candidate_build(grn_ctx *ctx,
                      token_candidate_data *data,
                      int offset)
{
  grn_rc rc = GRN_END_OF_DATA;
  int last = 0;
  GRN_BIT_SCAN_REV(data->selected_candidate, last);
  int i;
  for (i = 1; i <= last; i++) {
    if (data->selected_candidate & (1 << i)) {
      token_info *ti;
      token_candidate_node *node = data->nodes + i + offset;
      switch (node->status) {
      case GRN_TOKEN_CURSOR_DOING :
        {
          uint32_t size;
          const char *key = _grn_table_key(ctx,
                                           data->select_data->lexicon,
                                           node->tid,
                                           &size);
          ti = token_info_open(ctx,
                               data->select_data,
                               key,
                               size,
                               node->pos,
                               EX_NONE);
        }
        break;
      case GRN_TOKEN_CURSOR_DONE :
        if (node->tid) {
          uint32_t size;
          const char *key = _grn_table_key(ctx,
                                           data->select_data->lexicon,
                                           node->tid,
                                           &size);
          ti = token_info_open(ctx,
                               data->select_data,
                               key,
                               size,
                               node->pos,
                               node->ef & EX_PREFIX);
          break;
        } /* else fallthru */
      default :
        ti = token_info_open(ctx,
                             data->select_data,
                             (char *)node->token,
                             node->token_size,
                             node->pos,
                             node->ef & EX_PREFIX);
        break;
      }
      if (!ti) {
        goto exit;
      }
      data->select_data->token_infos[data->select_data->n_token_infos++] = ti;
      GRN_LOG(ctx,
              GRN_LOG_DEBUG,
              "[ii][overlap_token_skip] tid=%u pos=%d estimated_size=%u",
              node->tid, node->pos, node->estimated_size);
    }
  }
  rc = GRN_SUCCESS;
exit :
  return rc;
}

grn_inline static grn_rc
token_info_build_skipping_overlap(grn_ctx *ctx,
                                  grn_ii_select_data *select_data,
                                  grn_token_cursor *token_cursor,
                                  grn_id tid,
                                  int ef)
{
  token_candidate_data data;
  grn_rc rc = token_candidate_init(ctx,
                                   &data,
                                   select_data,
                                   token_cursor,
                                   tid,
                                   ef);
  if (rc != GRN_SUCCESS) {
    return rc;
  }

  uint32_t offset = 0;
  uint32_t limit = TOKEN_CANDIDATE_SIZE - 1;
  while (offset < data.n_nodes - 1) {
    data.selected_candidate = 0;
    rc = token_candidate_select(ctx, &data, offset, limit);
    if (rc != GRN_SUCCESS) {
      goto exit;
    }
    rc = token_candidate_build(ctx, &data, offset);
    if (rc != GRN_SUCCESS) {
      goto exit;
    }
    offset += limit;
  }
  rc = GRN_SUCCESS;
exit :
  if (data.nodes) {
    GRN_FREE(data.nodes);
  }
  return rc;
}

grn_inline static grn_rc
token_info_build_phrase(grn_ctx *ctx,
                        grn_ii_select_data *data,
                        const char *phrase,
                        unsigned int phrase_len)
{
  token_info *ti;
  grn_rc rc = GRN_END_OF_DATA;
  const char *key;
  uint32_t size;
  grn_token_cursor *token_cursor =
    grn_ii_select_data_open_token_cursor(ctx,
                                         data,
                                         phrase,
                                         phrase_len,
                                         GRN_TOKENIZE_GET);
  if (!token_cursor) { return ctx->rc; }
  if (data->mode == GRN_OP_UNSPLIT) {
    if ((ti = token_info_open(ctx,
                              data,
                              (char *)token_cursor->orig,
                              token_cursor->orig_blen,
                              0,
                              EX_BOTH))) {
      data->token_infos[data->n_token_infos++] = ti;
      rc = GRN_SUCCESS;
    }
  } else {
    grn_id tid;
    int ef;
    grn_token *token;
    switch (data->mode) {
    case GRN_OP_PREFIX :
      ef = EX_PREFIX;
      break;
    case GRN_OP_SUFFIX :
      ef = EX_SUFFIX;
      break;
    case GRN_OP_PARTIAL :
      ef = EX_BOTH;
      break;
    default :
      ef = EX_NONE;
      break;
    }
    tid = grn_token_cursor_next(ctx, token_cursor);
    if (ctx->rc != GRN_SUCCESS) {
      rc = ctx->rc;
      goto exit;
    }
    token = grn_token_cursor_get_token(ctx, token_cursor);
    if (grn_token_get_force_prefix_search(ctx, token)) { ef |= EX_PREFIX; }
    switch (token_cursor->status) {
    case GRN_TOKEN_CURSOR_DOING :
      key = _grn_table_key(ctx, data->lexicon, tid, &size);
      ti = token_info_open(ctx,
                           data,
                           key,
                           size,
                           token_cursor->pos,
                           ef & EX_SUFFIX);
      break;
    case GRN_TOKEN_CURSOR_DONE :
      ti = token_info_open(ctx,
                           data,
                           (const char *)token_cursor->curr,
                           token_cursor->curr_size,
                           0,
                           ef);
      break;
    case GRN_TOKEN_CURSOR_NOT_FOUND :
      ti = token_info_open(ctx,
                           data,
                           (char *)token_cursor->orig,
                           token_cursor->orig_blen,
                           0,
                           ef);
      break;
    case GRN_TOKEN_CURSOR_DONE_SKIP :
      data->only_skip_token = true;
      goto exit;
    default :
      goto exit;
    }
    if (!ti) { goto exit ; }
    data->token_infos[data->n_token_infos++] = ti;

    if (grn_ii_overlap_token_skip_enable) {
      rc = token_info_build_skipping_overlap(ctx, data, token_cursor, tid, ef);
      goto exit;
    }

    while (token_cursor->status == GRN_TOKEN_CURSOR_DOING) {
      grn_token *token;
      tid = grn_token_cursor_next(ctx, token_cursor);
      token = grn_token_cursor_get_token(ctx, token_cursor);
      if (grn_token_get_force_prefix_search(ctx, token)) { ef |= EX_PREFIX; }
      switch (token_cursor->status) {
      case GRN_TOKEN_CURSOR_DONE_SKIP :
        continue;
      case GRN_TOKEN_CURSOR_DOING :
        key = _grn_table_key(ctx, data->lexicon, tid, &size);
        ti = token_info_open(ctx, data, key, size, token_cursor->pos, EX_NONE);
        break;
      case GRN_TOKEN_CURSOR_DONE :
        if (tid) {
          key = _grn_table_key(ctx, data->lexicon, tid, &size);
          ti = token_info_open(ctx,
                               data,
                               key,
                               size,
                               token_cursor->pos,
                               ef & EX_PREFIX);
          break;
        } /* else fallthru */
      default :
        ti = token_info_open(ctx,
                             data,
                             (char *)token_cursor->curr,
                             token_cursor->curr_size,
                             token_cursor->pos,
                             ef & EX_PREFIX);
        break;
      }
      if (!ti) {
        goto exit;
      }
      data->token_infos[data->n_token_infos++] = ti;
    }
    rc = GRN_SUCCESS;
  }
exit :
  grn_token_cursor_close(ctx, token_cursor);
  return rc;
}

grn_inline static grn_rc
token_info_build(grn_ctx *ctx, grn_ii_select_data *data)
{
  data->only_skip_token = false;
  return token_info_build_phrase(ctx,
                                 data,
                                 data->query,
                                 data->query_len);
}

grn_inline static grn_rc
token_info_build_fuzzy(grn_ctx *ctx, grn_ii_select_data *data)
{
  token_info *ti;
  grn_rc rc = GRN_END_OF_DATA;
  grn_token_cursor *token_cursor =
    grn_ii_select_data_open_token_cursor(ctx,
                                         data,
                                         data->query,
                                         data->query_len,
                                         GRN_TOKENIZE_ONLY);
  data->only_skip_token = false;
  if (!token_cursor) { return ctx->rc; }
  grn_token_cursor_next(ctx, token_cursor);
  switch (token_cursor->status) {
  case GRN_TOKEN_CURSOR_DONE_SKIP :
    data->only_skip_token = true;
    goto exit;
  case GRN_TOKEN_CURSOR_DOING :
  case GRN_TOKEN_CURSOR_DONE :
    ti = token_info_open(ctx,
                         data,
                         (const char *)token_cursor->curr,
                         token_cursor->curr_size,
                         token_cursor->pos,
                         EX_FUZZY);
    break;
  default :
    ti = NULL;
    break;
  }
  if (!ti) {
    goto exit ;
  }
  data->token_infos[data->n_token_infos++] = ti;
  while (token_cursor->status == GRN_TOKEN_CURSOR_DOING) {
    grn_token_cursor_next(ctx, token_cursor);
    switch (token_cursor->status) {
    case GRN_TOKEN_CURSOR_DONE_SKIP :
      continue;
    case GRN_TOKEN_CURSOR_DOING :
    case GRN_TOKEN_CURSOR_DONE :
      ti = token_info_open(ctx,
                           data,
                           (const char *)token_cursor->curr,
                           token_cursor->curr_size,
                           token_cursor->pos,
                           EX_FUZZY);
      break;
    default :
      break;
    }
    if (!ti) {
      goto exit;
    }
    data->token_infos[data->n_token_infos++] = ti;
  }
  rc = GRN_SUCCESS;
exit :
  grn_token_cursor_close(ctx, token_cursor);
  return rc;
}

grn_inline static grn_rc
token_info_build_near_phrase(grn_ctx *ctx,
                             grn_ii_select_data *data)
{
  const char *tag = "[ii][token-info][build]";
  grn_rc rc = GRN_SUCCESS;
  data->only_skip_token = false;
  grn_obj buffer;
  GRN_TEXT_INIT(&buffer, 0);
  const char *current = data->query;
  const char *query_end = current + data->query_len;
  const char *last_char = NULL;
  int last_char_len = 0;
  bool in_paren = false;
  uint32_t phrase_group_id = 0;
  uint32_t phrase_id = 0;
  const bool is_product_mode =
    (data->mode == GRN_OP_NEAR_PHRASE_PRODUCT ||
     data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT);

  if (is_product_mode) {
    phrase_group_id--;
  }

  while (current < query_end) {
    int space_char_len = grn_isspace(current, ctx->encoding);
    if (space_char_len > 0) {
      current += space_char_len;
      continue;
    }

    const char *phrase = NULL;
    size_t phrase_len = 0;
    bool use_buffer = false;
    GRN_BULK_REWIND(&buffer);
    bool escaping = false;
    int char_len = grn_charlen(ctx, current, query_end);
    if (char_len == 0) {
      ERR(GRN_INVALID_ARGUMENT,
          "%s invalid character: <%0x>: <%.*s>",
          tag,
          current[0],
          (int)(data->query_len),
          data->query);
      goto exit;
    }

    if (is_product_mode) {
      if (char_len == 1 && current[0] == GRN_QUERY_PARENL) {
        if (in_paren) {
          ERR(GRN_INVALID_ARGUMENT,
              "%s parenthesis must not be nested: <%.*s|%.*s|%.*s>",
              tag,
              (int)(current - data->query),
              data->query,
              char_len,
              current,
              (int)((data->query + data->query_len) - current - char_len),
              current + char_len);
          goto exit;
        }
        in_paren = true;
        phrase_group_id++;
        current += char_len;
        continue;
      } else if (char_len == 1 && current[0] == GRN_QUERY_PARENR) {
        if (!in_paren) {
          ERR(GRN_INVALID_ARGUMENT,
              "%s unbalanced close parenthesis is detected: <%.*s|%.*s|%.*s>",
              tag,
              (int)(current - data->query),
              data->query,
              char_len,
              current,
              (int)((data->query + data->query_len) - current - char_len),
              current + char_len);
          goto exit;
        }
        in_paren = false;
        current += char_len;
        continue;
      } else {
        if (!in_paren) {
          ERR(GRN_INVALID_ARGUMENT,
              "%s all phrases must be in parenthesis: <%.*s|%.*s|%.*s>",
              tag,
              (int)(current - data->query),
              data->query,
              char_len,
              current,
              (int)((data->query + data->query_len) - current - char_len),
              current + char_len);
          goto exit;
        }
      }
    }

    if (char_len == 1 && current[0] == GRN_QUERY_QUOTEL) {
      use_buffer = true;
      current += char_len;
      while (current < query_end) {
        char_len = grn_charlen(ctx, current, query_end);
        if (char_len == 0) {
          ERR(GRN_INVALID_ARGUMENT,
              "%s invalid character: <%0x>: <%.*s>",
              tag,
              current[0],
              (int)(data->query_len),
              data->query);
          goto exit;
        }
        if (escaping) {
          escaping = false;
          last_char = NULL;
          last_char_len = 0;
        } else {
          if (char_len == 1) {
            if (current[0] == GRN_QUERY_ESCAPE) {
              escaping = true;
              current += char_len;
              continue;
            } else if (current[0] == GRN_QUERY_QUOTER) {
              current += char_len;
              break;
            }
          }
          last_char = current;
          last_char_len = char_len;
        }
        GRN_TEXT_PUT(ctx, &buffer, current, char_len);
        current += char_len;
      }
      phrase = GRN_TEXT_VALUE(&buffer);
      phrase_len = GRN_TEXT_LEN(&buffer);
    } else {
      phrase = current;
      while (current < query_end) {
        if (!escaping) {
          space_char_len = grn_isspace(current, ctx->encoding);
          if (space_char_len > 0) {
            break;
          }
        }
        char_len = grn_charlen(ctx, current, query_end);
        if (char_len == 0) {
          ERR(GRN_INVALID_ARGUMENT,
              "%s invalid character: <%0x>: <%.*s>",
              tag,
              current[0],
              (int)(data->query_len),
              data->query);
          goto exit;
        }
        if (escaping) {
          escaping = false;
          last_char = NULL;
          last_char_len = 0;
        } else {
          if (char_len == 1) {
            if (current[0] == GRN_QUERY_ESCAPE) {
              if (!use_buffer) {
                use_buffer = true;
                GRN_TEXT_PUT(ctx, &buffer, phrase, current - phrase);
              }
              current += char_len;
              escaping = true;
              continue;
            } else if (current[0] == GRN_QUERY_QUOTEL) {
              break;
            } else if (is_product_mode &&
                       (current[0] == GRN_QUERY_PARENL ||
                        current[0] == GRN_QUERY_PARENR)) {
              break;
            }
          }
          last_char = current;
          last_char_len = char_len;
        }
        if (use_buffer) {
          GRN_TEXT_PUT(ctx, &buffer, current, char_len);
        }
        current += char_len;
      }
      if (use_buffer) {
        phrase = GRN_TEXT_VALUE(&buffer);
        phrase_len = GRN_TEXT_LEN(&buffer);
      } else {
        phrase_len = current - phrase;
      }
    }

    if (phrase_len == 0) {
      continue;
    }

    bool must_last = false;
    if (!(data->mode == GRN_OP_ORDERED_NEAR_PHRASE ||
          data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT)) {
      if (last_char_len == 1 && *last_char == '$') {
        phrase_len -= last_char_len;
        must_last = true;
      }
    }

    uint32_t n_before = data->n_token_infos;
    rc = token_info_build_phrase(ctx, data, phrase, phrase_len);
    if (rc == GRN_END_OF_DATA && is_product_mode) {
      rc = GRN_SUCCESS;
      uint32_t i;
      for (i = n_before; i < data->n_token_infos; i++) {
        token_info_close(ctx, data->token_infos[i]);
      }
      data->n_token_infos = n_before;
      continue;
    } else if (rc != GRN_SUCCESS) {
      goto exit;
    }
    if (data->n_token_infos > n_before) {
      data->token_infos[data->n_token_infos - 1]->must_last = must_last;
    }
    must_last = false;
    uint32_t i;
    for (i = n_before; i < data->n_token_infos; i++) {
      data->token_infos[i]->n_tokens_in_phrase = data->n_token_infos - n_before;
      data->token_infos[i]->phrase_group_id = phrase_group_id;
      data->token_infos[i]->phrase_id = phrase_id;
    }
    phrase_id++;
  }

  if (is_product_mode && in_paren) {
    ERR(GRN_INVALID_ARGUMENT,
        "%s close parenthesis is missing",
        tag);
    goto exit;
  }

  data->n_phrase_groups = phrase_group_id + 1;
  data->n_phrases = phrase_id;

  if (data->mode == GRN_OP_ORDERED_NEAR_PHRASE) {
    if (data->n_token_infos > 0) {
      data->token_infos[data->n_token_infos - 1]->must_last = true;
    }
  }

exit:
  GRN_OBJ_FIN(ctx, &buffer);
  return rc;
}

static void
token_info_clear_offset(token_info **tis, uint32_t n)
{
  token_info **tie;
  for (tie = tis + n; tis < tie; tis++) { (*tis)->offset = 0; }
}


grn_inline static void
bt_zap(btr *bt)
{
  bt->n = 0;
  bt->min = NULL;
  bt->max = NULL;
  bt->root = NULL;
  bt->n_must_lasts = 0;
}

grn_inline static btr *
bt_open(grn_ctx *ctx, int size)
{
  btr *bt = GRN_CALLOC(sizeof(btr));
  if (bt) {
    bt_zap(bt);
    if (!(bt->nodes = GRN_MALLOC(sizeof(btr_node) * size))) {
      GRN_FREE(bt);
      bt = NULL;
    }
  }
  return bt;
}

grn_inline static void
bt_close(grn_ctx *ctx, btr *bt)
{
  if (!bt) { return; }
  GRN_FREE(bt->nodes);
  GRN_FREE(bt);
}

/* Adds a token info to the given tree. btr::min and btr::max are updated
 * are updated when the given token info is minimum or maximum token info
 * in the given tree. */
grn_inline static void
bt_push(btr *bt, token_info *ti)
{
  bool min_p = true;
  bool max_p = true;
  int32_t pos = ti->pos;
  btr_node *node, *new, **last;
  new = bt->nodes + bt->n++;
  new->ti = ti;
  new->car = NULL;
  new->cdr = NULL;
  for (last = &bt->root; (node = *last);) {
    if (pos < node->ti->pos) {
      last = &node->car;
      max_p = false;
    } else {
      last = &node->cdr;
      min_p = false;
    }
  }
  *last = new;
  if (min_p) { bt->min = ti; }
  if (max_p) { bt->max = ti; }
  if (ti->must_last) {
    bt->n_must_lasts++;
  }
}

/* Drops the minimum token info. Note that you can't push a token info to
 * this btr after this function is called. */
grn_inline static void
bt_pop(btr *bt)
{
  btr_node *min;
  btr_node *parent = NULL;
  btr_node **last;
  for (last = &bt->root;
       (min = *last) && min->car;
       parent = min, last = &min->car) {
  }
  if (min) {
    *last = min->cdr;
    if (min->cdr) {
      btr_node *new_min;
      for (new_min = min->cdr; new_min->car; new_min = new_min->car) ;
      bt->min = new_min->ti;
    } else if (parent) {
      bt->min = parent->ti;
    } else {
      bt->min = NULL;
    }
    if (last == &(bt->root)) {
      bt->max = bt->min;
    }
    min->cdr = NULL;
    bt->n--;
    if (min->ti->must_last) {
      bt->n_must_lasts--;
    }
  }
}

/* Replace the token info of the minimum node. Note that bt->min may
 * not be correct until you call bt_reorder_min(). */
grn_inline static void
bt_replace_min(btr *bt, token_info *ti)
{
  btr_node *min, **last;
  if (ti->must_last) {
    bt->n_must_lasts++;
  }
  for (last = &bt->root; (min = *last) && min->car; last = &min->car) ;
  if (min) {
    if (min->ti->must_last) {
      bt->n_must_lasts--;
    }
    min->ti = ti;
    bt->min = ti;
  }
}

/* Re-order the minimum token info. The minimum token info must be
 * updated before you call this function. */
grn_inline static void
bt_reorder_min(btr *bt)
{
  btr_node *node, *min, **last;
  for (last = &bt->root; (min = *last) && min->car; last = &min->car) ;
  if (min) {
    bool min_p = true;
    bool max_p = true;
    int32_t pos = min->ti->pos;
    *last = min->cdr;
    min->cdr = NULL;
    for (last = &bt->root; (node = *last);) {
      if (pos < node->ti->pos) {
        last = &node->car;
        max_p = false;
      } else {
        last = &node->cdr;
        min_p = false;
      }
    }
    *last = min;
    if (max_p) { bt->max = min->ti; }
    if (!min_p) {
      btr_node *new_min;
      for (new_min = bt->root; new_min->car; new_min = new_min->car) ;
      bt->min = new_min->ti;
    }
  }
}

/* select */

grn_inline static void
grn_rset_add_record(grn_ctx *ctx,
                    grn_hash *rset,
                    grn_rset_posinfo *posinfo,
                    double score,
                    grn_operator op)
{
  grn_id id;
  grn_rset_recinfo *recinfo;
  switch (op) {
  case GRN_OP_OR :
    id = grn_hash_add(ctx,
                      rset,
                      posinfo,
                      rset->key_size,
                      (void **)&recinfo,
                      NULL);
    if (id != GRN_ID_NIL) {
      if (rset->obj.header.flags & GRN_OBJ_WITH_SUBREC) {
        grn_table_add_subrec(ctx, (grn_obj *)rset, recinfo, score, posinfo, 1);
        grn_selector_data_current_add_score(ctx,
                                            (grn_obj *)rset,
                                            id,
                                            posinfo->rid,
                                            score);
      }
    }
    break;
  case GRN_OP_AND :
    id = grn_hash_get(ctx,
                      rset,
                      posinfo,
                      rset->key_size,
                      (void **)&recinfo);
    if (id != GRN_ID_NIL) {
      if (rset->obj.header.flags & GRN_OBJ_WITH_SUBREC) {
        recinfo->n_subrecs |= GRN_RSET_UTIL_BIT;
        grn_table_add_subrec(ctx, (grn_obj *)rset, recinfo, score, posinfo, 1);
        grn_selector_data_current_add_score(ctx,
                                            (grn_obj *)rset,
                                            id,
                                            posinfo->rid,
                                            score);
      }
    }
    break;
  case GRN_OP_AND_NOT :
    id = grn_hash_get(ctx, rset, posinfo, rset->key_size, (void **)&recinfo);
    if (id != GRN_ID_NIL) {
      grn_hash_delete_by_id(ctx, rset, id, NULL);
    }
    break;
  case GRN_OP_ADJUST :
    id = grn_hash_get(ctx, rset, posinfo, rset->key_size, (void **)&recinfo);
    if (id != GRN_ID_NIL) {
      if (rset->obj.header.flags & GRN_OBJ_WITH_SUBREC) {
        recinfo->score += score;
        grn_selector_data_current_add_score(ctx,
                                            (grn_obj *)rset,
                                            id,
                                            posinfo->rid,
                                            score);
      }
    }
    break;
  default :
    break;
  }
}

/* TODO: It may be better that we record the min ID when add/delete a
 * record. */
/* TODO: It may be useful that we just return approximate value. For
 * example, we can stop min ID search when we find an ID that is less
 * than grn_table_size(ctx, grn_ctx_at(ctx,
 * result_set->header.domain))/100. */
grn_id
grn_result_set_get_min_id(grn_ctx *ctx,
                          grn_hash *result_set)
{
  GRN_API_ENTER;
  if (!result_set) {
    GRN_API_RETURN(GRN_ID_NIL);
  }
  if (GRN_HASH_SIZE(result_set) == 0) {
    GRN_API_RETURN(GRN_ID_NIL);
  }
  grn_id min_id = GRN_ID_MAX;
  GRN_HASH_EACH_BEGIN(ctx, result_set, cursor, id) {
    void *key;
    grn_hash_cursor_get_key(ctx, cursor, &key);
    grn_id id = *((grn_id *)key);
    if (id < min_id) {
      min_id = id;
    }
  } GRN_HASH_EACH_END(ctx, cursor);
  GRN_API_RETURN(min_id);
}

grn_rc
grn_result_set_add_record(grn_ctx *ctx,
                          grn_hash *result_set,
                          grn_posting *posting,
                          grn_operator op)
{
  GRN_API_ENTER;
  grn_rset_add_record(ctx,
                      result_set,
                      (grn_rset_posinfo *)posting,
                      ((grn_posting_internal *)posting)->weight_float,
                      op);
  GRN_API_RETURN(ctx->rc);
}

grn_rc
grn_result_set_add_table(grn_ctx *ctx,
                         grn_hash *result_set,
                         grn_obj *table,
                         double score,
                         grn_operator op)
{
  GRN_API_ENTER;
  const int flags = GRN_CURSOR_BY_ID | GRN_CURSOR_ASCENDING;
  grn_table_cursor *cursor = grn_table_cursor_open(ctx,
                                                   table,
                                                   NULL, 0,
                                                   NULL, 0,
                                                   0, -1,
                                                   flags);
  if (cursor) {
    grn_result_set_add_table_cursor(ctx, result_set, cursor, score, op);
    grn_table_cursor_close(ctx, cursor);
  }
  GRN_API_RETURN(ctx->rc);
}

grn_rc
grn_result_set_add_table_cursor(grn_ctx *ctx,
                                grn_hash *result_set,
                                grn_table_cursor *cursor,
                                double score,
                                grn_operator op)
{
  GRN_API_ENTER;
  grn_obj *table = grn_table_cursor_table(ctx, cursor);
  if (result_set->obj.header.domain != DB_OBJ(table)->id) {
    grn_obj result_set_inspected;
    grn_obj table_inspected;
    GRN_TEXT_INIT(&result_set_inspected, 0);
    GRN_TEXT_INIT(&table_inspected, 0);
    grn_inspect_limited(ctx, &result_set_inspected, (grn_obj *)result_set);
    grn_inspect_limited(ctx, &table_inspected, table);
    ERR(GRN_INVALID_ARGUMENT,
        "[result-set][add-table-cursor] "
        "table must be the domain of the result set: %.*s: %.*s",
        (int)GRN_TEXT_LEN(&result_set_inspected),
        GRN_TEXT_VALUE(&result_set_inspected),
        (int)GRN_TEXT_LEN(&table_inspected),
        GRN_TEXT_VALUE(&table_inspected));
    GRN_OBJ_FIN(ctx, &result_set_inspected);
    GRN_OBJ_FIN(ctx, &table_inspected);
    GRN_API_RETURN(ctx->rc);
  }

  grn_rc rc;
  if (op == GRN_OP_OR || op == GRN_OP_AND) {
    rc = grn_hash_add_table_cursor(ctx, result_set, cursor, score, op);
  } else {
    grn_rset_posinfo posinfo = {0};
    while ((posinfo.rid = grn_table_cursor_next(ctx, cursor))) {
      grn_rset_add_record(ctx, result_set, &posinfo, score, op);
      if (ctx->rc != GRN_SUCCESS) {
        break;
      }
    }
    rc = ctx->rc;
  }
  GRN_API_RETURN(rc);
}

grn_rc
grn_result_set_add_index_cursor(grn_ctx *ctx,
                                grn_hash *result_set,
                                grn_obj *cursor,
                                double additional_score,
                                double weight,
                                grn_operator op)
{
  GRN_API_ENTER;

  grn_obj *index_column = grn_index_cursor_get_index_column(ctx, cursor);
  if (result_set->obj.header.domain != DB_OBJ(index_column)->range) {
    grn_obj result_set_inspected;
    grn_obj index_column_inspected;
    GRN_TEXT_INIT(&result_set_inspected, 0);
    GRN_TEXT_INIT(&index_column_inspected, 0);
    grn_inspect_limited(ctx, &result_set_inspected, (grn_obj *)result_set);
    grn_inspect_limited(ctx, &index_column_inspected, index_column);
    ERR(GRN_INVALID_ARGUMENT,
        "[result-set][add-index-cursor] "
        "not an index column for the result set: %.*s: %.*s",
        (int)GRN_TEXT_LEN(&result_set_inspected),
        GRN_TEXT_VALUE(&result_set_inspected),
        (int)GRN_TEXT_LEN(&index_column_inspected),
        GRN_TEXT_VALUE(&index_column_inspected));
    GRN_OBJ_FIN(ctx, &result_set_inspected);
    GRN_OBJ_FIN(ctx, &index_column_inspected);
    GRN_API_RETURN(ctx->rc);
  }

  grn_rc rc;
  if (op == GRN_OP_OR || op == GRN_OP_AND) {
    rc = grn_hash_add_index_cursor(ctx,
                                   result_set,
                                   cursor,
                                   additional_score,
                                   weight,
                                   op);
  } else {
    grn_id term_id;
    grn_posting *posting;
    while ((posting = grn_index_cursor_next(ctx, cursor, &term_id))) {
      grn_rset_posinfo posinfo = {
        posting->rid,
        posting->sid,
        posting->pos,
      };
      grn_posting_internal *posting_internal = (grn_posting_internal *)posting;
      double score = (posting_internal->weight_float + additional_score) * weight;
      grn_rset_add_record(ctx, result_set, &posinfo, score, op);
      if (ctx->rc != GRN_SUCCESS) {
        break;
      }
    }
    rc = ctx->rc;
  }
  GRN_API_RETURN(rc);
}

grn_rc
grn_result_set_add_ii_cursor(grn_ctx *ctx,
                             grn_hash *result_set,
                             grn_ii_cursor *cursor,
                             double additional_score,
                             double weight,
                             grn_operator op)
{
  GRN_API_ENTER;

  grn_obj *index_column = (grn_obj *)(cursor->ii);
  if (result_set->obj.header.domain != DB_OBJ(index_column)->range) {
    grn_obj result_set_inspected;
    grn_obj index_column_inspected;
    GRN_TEXT_INIT(&result_set_inspected, 0);
    GRN_TEXT_INIT(&index_column_inspected, 0);
    grn_inspect_limited(ctx, &result_set_inspected, (grn_obj *)result_set);
    grn_inspect_limited(ctx, &index_column_inspected, index_column);
    ERR(GRN_INVALID_ARGUMENT,
        "[result-set][add-ii-cursor] "
        "not an index column for the result set: %.*s: %.*s",
        (int)GRN_TEXT_LEN(&result_set_inspected),
        GRN_TEXT_VALUE(&result_set_inspected),
        (int)GRN_TEXT_LEN(&index_column_inspected),
        GRN_TEXT_VALUE(&index_column_inspected));
    GRN_OBJ_FIN(ctx, &result_set_inspected);
    GRN_OBJ_FIN(ctx, &index_column_inspected);
    GRN_API_RETURN(ctx->rc);
  }

  grn_rc rc;
  if (op == GRN_OP_OR || op == GRN_OP_AND) {
    rc = grn_hash_add_ii_cursor(ctx,
                                result_set,
                                cursor,
                                additional_score,
                                weight,
                                op);
  } else {
    grn_posting *posting;
    while ((posting = grn_ii_cursor_next(ctx, cursor))) {
      grn_rset_posinfo posinfo = {
        posting->rid,
        posting->sid,
        posting->pos,
      };
      grn_posting_internal *posting_internal = (grn_posting_internal *)posting;
      double score = (posting_internal->weight_float + additional_score) * weight;
      grn_rset_add_record(ctx, result_set, &posinfo, score, op);
      if (ctx->rc != GRN_SUCCESS) {
        break;
      }
    }
    rc = ctx->rc;
  }
  GRN_API_RETURN(rc);
}

grn_rc
grn_result_set_add_ii_select_cursor(grn_ctx *ctx,
                                    grn_hash *result_set,
                                    grn_ii_select_cursor *cursor,
                                    grn_operator op)
{
  GRN_API_ENTER;

  grn_obj *index_column = (grn_obj *)grn_ii_select_cursor_get_ii(ctx, cursor);
  if (result_set->obj.header.domain != DB_OBJ(index_column)->range) {
    grn_obj result_set_inspected;
    grn_obj index_column_inspected;
    GRN_TEXT_INIT(&result_set_inspected, 0);
    GRN_TEXT_INIT(&index_column_inspected, 0);
    grn_inspect_limited(ctx, &result_set_inspected, (grn_obj *)result_set);
    grn_inspect_limited(ctx, &index_column_inspected, index_column);
    ERR(GRN_INVALID_ARGUMENT,
        "[result-set][add-ii-select-cursor] "
        "not an index column for the result set: %.*s: %.*s",
        (int)GRN_TEXT_LEN(&result_set_inspected),
        GRN_TEXT_VALUE(&result_set_inspected),
        (int)GRN_TEXT_LEN(&index_column_inspected),
        GRN_TEXT_VALUE(&index_column_inspected));
    GRN_OBJ_FIN(ctx, &result_set_inspected);
    GRN_OBJ_FIN(ctx, &index_column_inspected);
    GRN_API_RETURN(ctx->rc);
  }

  grn_rc rc;
  if (op == GRN_OP_OR || op == GRN_OP_AND) {
    rc = grn_hash_add_ii_select_cursor(ctx, result_set, cursor, op);
  } else {
    grn_ii_select_cursor_posting *posting;
    while ((posting = grn_ii_select_cursor_next(ctx, cursor))) {
      grn_rset_posinfo posinfo = {
        posting->rid,
        posting->sid,
        posting->pos,
      };
      grn_rset_add_record(ctx,
                          result_set,
                          &posinfo,
                          posting->score,
                          op);
      if (ctx->rc != GRN_SUCCESS) {
        break;
      }
    }
    rc = ctx->rc;
  }
  GRN_API_RETURN(rc);
}

grn_inline static void
res_add(grn_ctx *ctx,
        grn_hash *s,
        grn_rset_posinfo *pi,
        double score,
        grn_operator op)
{
  grn_rset_add_record(ctx, s, pi, score, op);
}

grn_rc
grn_ii_posting_add(grn_ctx *ctx, grn_posting *pos, grn_hash *s, grn_operator op)
{
  grn_rset_add_record(ctx,
                      s,
                      (grn_rset_posinfo *)(pos),
                      pos->weight,
                      op);
  return ctx->rc;
}

grn_rc
grn_ii_posting_add_float(grn_ctx *ctx,
                         grn_posting *pos,
                         grn_hash *s,
                         grn_operator op)
{
  return grn_result_set_add_record(ctx, s, pos, op);
}

static float
get_weight(grn_ctx *ctx, grn_ii_select_data *data)
{
  switch (data->wv_mode) {
  case GRN_WV_NONE :
    return 1;
  case GRN_WV_STATIC :
    if (data->sid <= (uint32_t)(data->optarg->vector_size)) {
      if (data->optarg->weight_vector) {
        return data->optarg->weight_vector[data->sid - 1];
      } else {
        return data->optarg->weight_vector_float[data->sid - 1];
      }
    } else {
      return 0;
    }
  case GRN_WV_DYNAMIC :
    /* todo : support hash with keys
    if (s->keys) {
      uint32_t key_size;
      const char *key = _grn_table_key(ctx, s->keys, rid, &key_size);
      // todo : change grn_select_optarg
      return key ? optarg->func(s, key, key_size, sid, optarg->func_arg) : 0;
    }
    */
    /* todo : cast */
    return data->optarg->func(ctx,
                              data->result_set,
                              (void *)(intptr_t)(data->rid),
                              data->sid,
                              data->optarg->func_arg);
  case GRN_WV_CONSTANT :
    if (data->optarg->vector_size < 0) {
      return data->optarg->weight_float;
    } else {
      return data->optarg->vector_size;
    }
  default :
    return 1;
  }
}

static void
grn_ii_select_data_init(grn_ctx *ctx,
                        grn_ii_select_data *data,
                        grn_select_optarg *optarg)
{
  data->optarg = optarg;
  data->mode = GRN_OP_EXACT;
  data->wv_mode = GRN_WV_NONE;
  data->score_func = NULL;
  data->previous_min = GRN_ID_NIL;
  data->current_min = GRN_ID_NIL;
  data->set_min_enable_for_and_query = GRN_FALSE;
  data->only_skip_token = GRN_FALSE;
  data->query_options = NULL;

  data->token_infos = NULL;
  data->n_token_infos = 0;
  data->n_phrase_groups = 0;
  data->phrase_groups = NULL;
  data->n_phrases = 0;

  data->bt = NULL;
  data->check_element_intervals_btree = NULL;

  data->rid = 0;
  data->sid = 0;
  data->next_rid = 0;
  data->next_sid = 0;

  if (!optarg) {
    return;
  }

  data->mode = optarg->mode;

  if (optarg->func) {
    data->wv_mode = GRN_WV_DYNAMIC;
  } else if (optarg->vector_size != 0) {
    if (optarg->weight_vector || optarg->weight_vector_float) {
      data->wv_mode = GRN_WV_STATIC;
    } else {
      data->wv_mode = GRN_WV_CONSTANT;
    }
  }

  if (optarg->match_info) {
    if (optarg->match_info->flags & GRN_MATCH_INFO_GET_MIN_RECORD_ID) {
      data->previous_min = optarg->match_info->min;
      data->set_min_enable_for_and_query = GRN_TRUE;
    }
  }

  if (optarg->scorer) {
    grn_proc *scorer = (grn_proc *)(optarg->scorer);
    data->score_func = scorer->callbacks.scorer.score;
    data->record.table = grn_ctx_at(ctx, data->result_set->obj.header.domain);
    data->record.lexicon = data->lexicon;
    data->record.id = GRN_ID_NIL;
    GRN_RECORD_INIT(&(data->record.terms), GRN_OBJ_VECTOR,
                    data->lexicon->header.domain);
    GRN_UINT32_INIT(&(data->record.term_weights), GRN_OBJ_VECTOR);
    data->record.total_term_weights = 0;
    data->record.n_documents = grn_table_size(ctx, data->record.table);
    data->record.n_occurrences = 0;
    data->record.n_candidates = 0;
    data->record.n_tokens = 0;
    data->record.weight = 0;
    data->record.args_expr = optarg->scorer_args_expr;
    data->record.args_expr_offset = optarg->scorer_args_expr_offset;
  }

  data->fuzzy_search_optarg = &(optarg->fuzzy);
  data->query_options = optarg->query_options;
}

static bool
grn_ii_select_data_init_token_infos(grn_ctx *ctx,
                                    grn_ii_select_data *data,
                                    const char *tag)
{
  if (data->query_len == 0) {
    return false;
  }

  data->token_infos = GRN_MALLOC(sizeof(token_info *) * data->query_len * 2);
  if (!data->token_infos) {
    char errbuf[GRN_CTX_MSGSIZE];
    grn_strcpy(errbuf, GRN_CTX_MSGSIZE, ctx->errbuf);
    ERR(ctx->rc,
        "%s failed to allocate token info container: %s",
        tag,
        errbuf);
    return false;
  }

  if (data->mode == GRN_OP_FUZZY) {
    grn_rc rc = token_info_build_fuzzy(ctx, data);
    if (rc != GRN_SUCCESS) {
      return false;
    }
    if (data->n_token_infos == 0) {
      return false;
    }
  } else if (data->mode == GRN_OP_NEAR_PHRASE ||
             data->mode == GRN_OP_ORDERED_NEAR_PHRASE ||
             data->mode == GRN_OP_NEAR_PHRASE_PRODUCT ||
             data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT) {
    grn_rc rc = token_info_build_near_phrase(ctx, data);
    if (rc != GRN_SUCCESS) {
      return false;
    }
  } else {
    grn_rc rc = token_info_build(ctx, data);
    if (rc != GRN_SUCCESS) {
      return false;
    }
  }
  if (data->n_token_infos == 0) {
    return false;
  }

  if (data->mode == GRN_OP_NEAR_PHRASE_PRODUCT ||
      data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT) {
    data->phrase_groups =
      GRN_MALLOC(sizeof(phrase_group) * data->n_phrase_groups);
    if (!data->phrase_groups) {
      return false;
    }
    uint32_t i;
    uint32_t i_token_info = 0;
    for (i = 0; i < data->n_phrase_groups; i++) {
      uint32_t n_phrases = 0;
      for (;
           i_token_info < data->n_token_infos &&
             data->token_infos[i_token_info]->phrase_group_id == i;
           i_token_info += data->token_infos[i_token_info]->n_tokens_in_phrase) {
        n_phrases++;
      }
      data->phrase_groups[i].n_phrases = n_phrases;
      data->phrase_groups[i].btree = bt_open(ctx, n_phrases);
    }
  } else {
    data->phrase_groups = NULL;
  }

  if (data->mode == GRN_OP_NEAR_NO_OFFSET) {
    token_info_clear_offset(data->token_infos, data->n_token_infos);
    data->mode = GRN_OP_NEAR;
  }
  switch (data->mode) {
  case GRN_OP_NEAR :
  case GRN_OP_NEAR_PHRASE :
  case GRN_OP_ORDERED_NEAR_PHRASE :
  case GRN_OP_NEAR_PHRASE_PRODUCT :
  case GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT :
    {
      size_t btree_size;
      if (data->mode == GRN_OP_NEAR_PHRASE_PRODUCT ||
          data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT) {
        btree_size = data->n_phrase_groups;
      } else {
        btree_size = data->n_token_infos;
      }
      data->bt = bt_open(ctx, btree_size);
      if (!data->bt) {
        char errbuf[GRN_CTX_MSGSIZE];
        grn_strcpy(errbuf, GRN_CTX_MSGSIZE, ctx->errbuf);
        ERR(ctx->rc,
            "%s failed to allocate btree: %s",
            tag,
            errbuf);
        return false;
      }
      data->max_interval = data->optarg->max_interval;
      data->additional_last_interval = data->optarg->additional_last_interval;
      data->max_element_intervals = data->optarg->max_element_intervals;
      if ((data->mode == GRN_OP_NEAR ||
           data->mode == GRN_OP_NEAR_PHRASE ||
           data->mode == GRN_OP_NEAR_PHRASE_PRODUCT) &&
          data->max_element_intervals &&
          GRN_INT32_VECTOR_SIZE(data->max_element_intervals) > 0) {
        data->check_element_intervals_btree = bt_open(ctx, btree_size);
        if (!data->check_element_intervals_btree) {
          char errbuf[GRN_CTX_MSGSIZE];
          grn_strcpy(errbuf, GRN_CTX_MSGSIZE, ctx->errbuf);
          ERR(ctx->rc,
              "%s failed to allocate btree for checking element intervals: %s",
              tag,
              errbuf);
          return false;
        }
      }
    }
    break;
  default :
    break;
  }
  qsort(data->token_infos,
        data->n_token_infos,
        sizeof(token_info *),
        token_compare);
  if (data->mode == GRN_OP_NEAR_PHRASE) {
    bool have_must_last = false;
    uint32_t i;
    for (i = 0; i < data->n_token_infos; i++) {
      if (data->token_infos[i]->must_last) {
        if (have_must_last) {
          /* Multiple last tokens query are never matched. */
          return false;
        }
        have_must_last = true;
      }
    }
  }
  return true;
}

static void
grn_ii_select_data_fin(grn_ctx *ctx,
                       grn_ii_select_data *data)
{
  if (data->score_func) {
    GRN_OBJ_FIN(ctx, &(data->record.terms));
    GRN_OBJ_FIN(ctx, &(data->record.term_weights));
  }

  if (data->set_min_enable_for_and_query &&
      !data->only_skip_token) {
    if (data->current_min > data->previous_min) {
      data->optarg->match_info->min = data->current_min;
    }
  }

  if (data->only_skip_token && data->optarg && data->optarg->match_info) {
    data->optarg->match_info->flags |= GRN_MATCH_INFO_ONLY_SKIP_TOKEN;
  }

  if (data->phrase_groups) {
    uint32_t i;
    for (i = 0; i < data->n_phrase_groups; i++) {
      bt_close(ctx, data->phrase_groups[i].btree);
    }
    GRN_FREE(data->phrase_groups);
  }

  if (data->token_infos) {
    token_info **token_info;
    for (token_info = data->token_infos;
         token_info < data->token_infos + data->n_token_infos;
         token_info++) {
      if (*token_info) {
        token_info_close(ctx, *token_info);
      }
    }
    GRN_FREE(data->token_infos);
  }

  if (data->bt) {
    bt_close(ctx, data->bt);
  }

  if (data->check_element_intervals_btree) {
    bt_close(ctx, data->check_element_intervals_btree);
  }
}

static grn_rc
grn_ii_similar_search_internal(grn_ctx *ctx, grn_ii_select_data *data)
{
  int *w1;
  uint32_t limit;
  grn_id tid, *tp, max_size;
  grn_rc rc = GRN_SUCCESS;
  grn_hash *h;
  grn_token_cursor *token_cursor;
  if (!data->lexicon ||
      !data->query ||
      !data->query_len ||
      !data->result_set ||
      !data->optarg) {
    return GRN_INVALID_ARGUMENT;
  }
  if (!(h = grn_hash_create(ctx, NULL, sizeof(grn_id), sizeof(int), 0))) {
    return GRN_NO_MEMORY_AVAILABLE;
  }
  token_cursor = grn_ii_select_data_open_token_cursor(ctx,
                                                      data,
                                                      data->query,
                                                      data->query_len,
                                                      GRN_TOKENIZE_GET);
  if (!token_cursor) {
    grn_hash_close(ctx, h);
    return ctx->rc;
  }
  if (!(max_size = data->optarg->max_size)) { max_size = 1048576; }
  while (token_cursor->status != GRN_TOKEN_CURSOR_DONE &&
         token_cursor->status != GRN_TOKEN_CURSOR_DONE_SKIP) {
    if ((tid = grn_token_cursor_next(ctx, token_cursor))) {
      if (grn_hash_add(ctx, h, &tid, sizeof(grn_id), (void **)&w1, NULL)) {
        (*w1)++;
      }
    }
    if (tid && token_cursor->curr_size) {
      if (data->mode == GRN_OP_UNSPLIT) {
        grn_table_search(ctx,
                         data->lexicon,
                         token_cursor->curr,
                         token_cursor->curr_size,
                         GRN_OP_PREFIX,
                         (grn_obj *)h,
                         GRN_OP_OR);
      }
      if (data->mode == GRN_OP_PARTIAL) {
        grn_table_search(ctx,
                         data->lexicon,
                         token_cursor->curr,
                         token_cursor->curr_size,
                         GRN_OP_SUFFIX,
                         (grn_obj *)h,
                         GRN_OP_OR);
      }
    }
  }
  grn_token_cursor_close(ctx, token_cursor);
  {
    grn_hash_cursor *c = grn_hash_cursor_open(ctx, h, NULL, 0, NULL, 0,
                                              0, -1, 0);
    if (!c) {
      GRN_LOG(ctx, GRN_LOG_ALERT,
              "grn_hash_cursor_open on grn_ii_similar_search failed !");
      grn_hash_close(ctx, h);
      return GRN_NO_MEMORY_AVAILABLE;
    }
    while (grn_hash_cursor_next(ctx, c)) {
      uint32_t es;
      grn_hash_cursor_get_key_value(ctx, c, (void **)&tp, NULL, (void **)&w1);
      if ((es = grn_ii_estimate_size(ctx, data->ii, *tp))) {
        *w1 += max_size / es;
      } else {
        grn_hash_cursor_delete(ctx, c, NULL);
      }
    }
    grn_hash_cursor_close(ctx, c);
  }
  limit = data->optarg->similarity_threshold
    ? ((uint32_t)(data->optarg->similarity_threshold) > GRN_HASH_SIZE(h)
       ? GRN_HASH_SIZE(h)
       :(uint32_t)(data->optarg->similarity_threshold))
    : (GRN_HASH_SIZE(h) >> 3) + 1;
  if (GRN_HASH_SIZE(h)) {
    grn_id j, id;
    int w2, rep;
    grn_ii_cursor *c;
    grn_posting *pos;
    grn_table_sort_optarg arg = {
      GRN_TABLE_SORT_DESC|GRN_TABLE_SORT_BY_VALUE|GRN_TABLE_SORT_AS_NUMBER,
      NULL,
      NULL,
      NULL,
      0
    };
    grn_array *sorted = grn_array_create(ctx, NULL, sizeof(grn_id), 0);
    if (!sorted) {
      GRN_LOG(ctx, GRN_LOG_ALERT,
              "grn_hash_sort on grn_ii_similar_search failed !");
      grn_hash_close(ctx, h);
      return GRN_NO_MEMORY_AVAILABLE;
    }
    grn_hash_sort(ctx, h, limit, sorted, &arg);
    /* todo support subrec
    rep = (s->record_unit == GRN_REC_POSITION || s->subrec_unit == GRN_REC_POSITION);
    */
    rep = 0;
    for (j = 1; j <= limit; j++) {
      grn_array_get_value(ctx, sorted, j, &id);
      _grn_hash_get_key_value(ctx, h, id, (void **) &tp, (void **) &w1);
      if (!*tp || !(c = grn_ii_cursor_open(ctx,
                                           data->ii,
                                           *tp,
                                           GRN_ID_NIL,
                                           GRN_ID_MAX,
                                           rep
                                           ? data->ii->n_elements
                                           : data->ii->n_elements - 1, 0))) {
        GRN_LOG(ctx, GRN_LOG_ERROR, "cursor open failed (%d)", *tp);
        continue;
      }
      if (rep) {
        while (grn_ii_cursor_next(ctx, c)) {
          pos = c->post;
          data->rid = pos->rid;
          data->sid = pos->sid;
          if ((w2 = get_weight(ctx, data)) > 0) {
            while (grn_ii_cursor_next_pos(ctx, c)) {
              float pos_weight = grn_posting_get_weight_float(ctx, pos);
              res_add(ctx,
                      data->result_set,
                      (grn_rset_posinfo *)pos,
                      *w1 * w2 * (1 + pos_weight),
                      data->op);
            }
          }
        }
      } else {
        while (grn_ii_cursor_next(ctx, c)) {
          pos = c->post;
          data->rid = pos->rid;
          data->sid = pos->sid;
          if ((w2 = get_weight(ctx, data)) > 0) {
            float pos_weight = grn_posting_get_weight_float(ctx, pos);
            res_add(ctx,
                    data->result_set,
                    (grn_rset_posinfo *)pos,
                    *w1 * w2 * (pos->tf + pos_weight),
                    data->op);
          }
        }
      }
      grn_ii_cursor_close(ctx, c);
    }
    grn_array_close(ctx, sorted);
  }
  grn_hash_close(ctx, h);
  grn_ii_resolve_sel_and(ctx, data->result_set, data->op);
  //  grn_hash_cursor_clear(r);
  return rc;
}

grn_rc
grn_ii_similar_search(grn_ctx *ctx, grn_ii *ii,
                      const char *string, unsigned int string_len,
                      grn_hash *s, grn_operator op, grn_select_optarg *optarg)
{
  grn_ii_select_data data;
  data.ii = ii;
  data.lexicon = data.ii->lexicon;
  data.query = string;
  data.query_len = string_len;
  data.result_set = s;
  data.op = op;
  grn_ii_select_data_init(ctx, &data, optarg);
  return grn_ii_similar_search_internal(ctx, &data);
}

#define TERM_EXTRACT_EACH_POST 0
#define TERM_EXTRACT_EACH_TERM 1

static grn_rc
grn_ii_term_extract_internal(grn_ctx *ctx, grn_ii_select_data *data)
{
  grn_rset_posinfo pi;
  grn_id tid;
  const char *p, *pe;
  grn_obj *nstr;
  const char *normalized;
  unsigned int normalized_length_in_bytes;
  grn_ii_cursor *c;
  grn_posting *pos;
  int skip, rep, policy;
  grn_rc rc = GRN_SUCCESS;
  if (!data->ii ||
      !data->query ||
      !data->query_len ||
      !data->result_set ||
      !data->optarg) {
    return GRN_INVALID_ARGUMENT;
  }
  if (!(nstr = grn_string_open(ctx, data->query, data->query_len, NULL, 0))) {
    return GRN_INVALID_ARGUMENT;
  }
  policy = data->optarg->max_interval;
  /* todo support subrec
  if (policy == TERM_EXTRACT_EACH_POST) {
    if ((rc = grn_records_reopen(s, GRN_REC_SECTION, GRN_REC_NONE, 0))) { goto exit; }
  }
  rep = (s->record_unit == GRN_REC_POSITION || s->subrec_unit == GRN_REC_POSITION);
  */
  rep = 0;
  grn_string_get_normalized(ctx, nstr, &normalized, &normalized_length_in_bytes,
                            NULL);
  for (p = normalized, pe = p + normalized_length_in_bytes; p < pe; p += skip) {
    if ((tid = grn_table_lcp_search(ctx, data->ii->lexicon, p, pe - p))) {
      if (policy == TERM_EXTRACT_EACH_POST) {
        if (!(skip = grn_table_get_key(ctx, data->ii->lexicon, tid, NULL, 0))) {
          break;
        }
      } else {
        if (!(skip = (int)grn_charlen(ctx, p, pe))) { break; }
      }
      if (!(c = grn_ii_cursor_open(ctx, data->ii, tid, GRN_ID_NIL, GRN_ID_MAX,
                                   rep
                                   ? data->ii->n_elements
                                   : data->ii->n_elements - 1, 0))) {
        GRN_LOG(ctx, GRN_LOG_ERROR, "cursor open failed (%d)", tid);
        continue;
      }
      if (rep) {
        while (grn_ii_cursor_next(ctx, c)) {
          pos = c->post;
          data->rid = pos->rid;
          data->sid = pos->sid;
          while (grn_ii_cursor_next_pos(ctx, c)) {
            res_add(ctx,
                    data->result_set,
                    (grn_rset_posinfo *)pos,
                    get_weight(ctx, data),
                    data->op);
          }
        }
      } else {
        while (grn_ii_cursor_next(ctx, c)) {
          if (policy == TERM_EXTRACT_EACH_POST) {
            pi.rid = c->post->rid;
            pi.sid = p - normalized;
            res_add(ctx, data->result_set, &pi, pi.sid + 1, data->op);
          } else {
            pos = c->post;
            data->rid = pos->rid;
            data->sid = pos->sid;
            res_add(ctx,
                    data->result_set,
                    (grn_rset_posinfo *)pos,
                    get_weight(ctx, data),
                    data->op);
          }
        }
      }
      grn_ii_cursor_close(ctx, c);
    } else {
      if (!(skip = (int)grn_charlen(ctx, p, pe))) {
        break;
      }
    }
  }
  grn_obj_close(ctx, nstr);
  return rc;
}

grn_rc
grn_ii_term_extract(grn_ctx *ctx, grn_ii *ii, const char *string,
                    unsigned int string_len, grn_hash *s,
                    grn_operator op, grn_select_optarg *optarg)
{
  grn_ii_select_data data;
  data.ii = ii;
  data.lexicon = data.ii->lexicon;
  data.query = string;
  data.query_len = string_len;
  data.result_set = s;
  data.op = op;
  grn_ii_select_data_init(ctx, &data, optarg);
  return grn_ii_term_extract_internal(ctx, &data);
}

struct grn_ii_select_cursor_ {
  grn_ii_select_data data;
  bool per_occurrence_mode;
  grn_ii_select_cursor_posting posting;
  bool done;
  grn_ii_select_cursor_posting unshifted_posting;
  bool have_unshifted_posting;
};

static void
grn_ii_select_cursor_init_internal(grn_ctx *ctx,
                                   grn_ii_select_cursor *cursor)
{
  cursor->per_occurrence_mode = false;
  cursor->done = false;
  cursor->have_unshifted_posting = false;
}

static grn_rc
grn_ii_select_cursor_close(grn_ctx *ctx,
                           grn_ii_select_cursor *cursor)
{
  if (!cursor) {
    return GRN_SUCCESS;
  }

  grn_ii_select_data_fin(ctx, &(cursor->data));
  GRN_FREE(cursor);

  return GRN_SUCCESS;
}

static grn_ii_select_cursor *
grn_ii_select_cursor_open(grn_ctx *ctx,
                          grn_ii *ii,
                          const char *string,
                          unsigned int string_len,
                          grn_select_optarg *optarg)
{
  const char *tag = "[ii][select][cursor][open]";

  if (string_len == 0) {
    ERR(GRN_INVALID_ARGUMENT,
        "%s empty string",
        tag);
    return NULL;
  }

  grn_ii_select_cursor *cursor = GRN_CALLOC(sizeof(grn_ii_select_cursor));
  if (!cursor) {
    char errbuf[GRN_CTX_MSGSIZE];
    grn_strcpy(errbuf, GRN_CTX_MSGSIZE, ctx->errbuf);
    ERR(ctx->rc,
        "%s failed to allocate cursor: %s",
        tag,
        errbuf);
    return NULL;
  }

  cursor->data.ii = ii;
  cursor->data.lexicon = cursor->data.ii->lexicon;
  cursor->data.query = string;
  cursor->data.query_len = string_len;
  cursor->data.result_set = NULL;
  cursor->data.op = GRN_OP_OR;
  grn_ii_select_data_init(ctx, &(cursor->data), optarg);
  switch (cursor->data.mode) {
  case GRN_OP_EXACT :
  case GRN_OP_FUZZY :
  case GRN_OP_NEAR :
  case GRN_OP_NEAR_NO_OFFSET :
    break;
  default :
    ERR(GRN_INVALID_ARGUMENT,
        "%s EXACT, FUZZY, NEAR and NEAR_NO_OFFSET are only supported mode: %s",
        tag,
        grn_operator_to_string(cursor->data.mode));
    grn_ii_select_cursor_close(ctx, cursor);
    return NULL;
  }

  if (!grn_ii_select_data_init_token_infos(ctx,
                                           &(cursor->data),
                                           tag)) {
    grn_ii_select_cursor_close(ctx, cursor);
    return NULL;
  }
  if (cursor->data.n_token_infos == 0) {
    grn_ii_select_cursor_close(ctx, cursor);
    return NULL;
  }

  GRN_LOG(ctx, GRN_LOG_INFO,
          "%s n=%d <%.*s>",
          tag,
          cursor->data.n_token_infos,
          string_len, string);

  grn_ii_select_cursor_init_internal(ctx, cursor);

  return cursor;
}

static void
grn_ii_select_cursor_set_per_occurrence_mode(grn_ctx *ctx,
                                             grn_ii_select_cursor *cursor,
                                             bool mode)
{
  cursor->per_occurrence_mode = mode;
}

grn_inline static bool
grn_ii_select_skip_pos(grn_ctx *ctx,
                       grn_ii_select_data *data,
                       int32_t pos)
{
  if (token_info_skip_pos(ctx,
                          data->token_info,
                          data->rid,
                          data->sid,
                          pos) != GRN_SUCCESS) {
    return false;
  }
  if (data->token_info->p->rid != data->rid ||
      data->token_info->p->sid != data->sid) {
    if (!(data->mode == GRN_OP_NEAR_PHRASE_PRODUCT ||
          data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT)) {
      data->next_rid = data->token_info->p->rid;
      data->next_sid = data->token_info->p->sid;
    }
    return false;
  }
  return true;
}

grn_inline static bool
grn_ii_select_data_find_phrase(grn_ctx *ctx,
                               grn_ii_select_data *data,
                               uint32_t phrase_id,
                               int32_t start_pos)
{
  token_info **tip;
  token_info **tis = data->token_infos;
  token_info **tie = tis + data->n_token_infos;
  uint32_t n_tokens_in_same_pos = 0;
  for (tip = tis; ; tip++) {
    if (tip == tie) { tip = tis; }
    data->token_info = *tip;
    if (data->token_info->phrase_id != phrase_id) {
      continue;
    }
    if (!grn_ii_select_skip_pos(ctx, data, start_pos)) {
      return false;
    }
    if (data->token_info->pos == start_pos) {
      n_tokens_in_same_pos++;
    } else {
      n_tokens_in_same_pos = 1;
      start_pos = data->token_info->pos;
    }
    if (n_tokens_in_same_pos == data->token_info->n_tokens_in_phrase) {
      return true;
    }
  }
  return false;
}

grn_inline static bool
grn_ii_select_data_find_phrase_product(grn_ctx *ctx,
                                       grn_ii_select_data *data,
                                       int32_t start_pos)
{
  uint32_t phrase_group_id = data->token_info->phrase_group_id;
  phrase_group *group = &(data->phrase_groups[phrase_group_id]);
  bool skipped = false;
  token_info *min_before = group->btree->min;
  while (true) {
    data->token_info = group->btree->min;
    if (grn_ii_select_data_find_phrase(ctx,
                                       data,
                                       data->token_info->phrase_id,
                                       start_pos)) {
      skipped = true;
      bt_reorder_min(group->btree);
      if (group->btree->min == min_before) {
        break;
      }
      if (group->btree->min->pos == min_before->pos) {
        break;
      }
      min_before = group->btree->min;
    } else {
      bt_pop(group->btree);
      if (!group->btree->min) {
        break;
      }
    }
  }
  if (!skipped) {
    return false;
  }
  bt_replace_min(data->bt, group->btree->min);
  return true;
}

grn_inline static bool
grn_ii_select_data_is_matched_near_phrase(grn_ctx *ctx,
                                          grn_ii_select_data *data,
                                          int interval)
{
  if (data->max_interval < 0) {
    return true;
  }
  if (data->additional_last_interval == 0) {
    return (interval <= data->max_interval);
  }

  token_info *max_token_info = NULL;
  int min_without_last_token = -1;
  int max_without_last_token = -1;
  if (data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT) {
    uint32_t i;
    uint32_t n = data->n_phrase_groups;
    for (i = 0; i < n - 1; i++) {
      token_info *ti = data->phrase_groups[i].btree->min;
      if (min_without_last_token == -1 ||
          ti->pos < min_without_last_token) {
        min_without_last_token = ti->pos;
      }
      if (max_without_last_token == -1 ||
          ti->pos > max_without_last_token) {
        max_without_last_token = ti->pos;
        max_token_info = ti;
      }
    }
  } else if (data->mode == GRN_OP_NEAR_PHRASE_PRODUCT) {
    uint32_t i;
    uint32_t n = data->n_phrase_groups;
    for (i = 0; i < n; i++) {
      token_info *ti = data->phrase_groups[i].btree->min;
      if (ti->must_last) {
        continue;
      }
      if (min_without_last_token == -1 ||
          ti->pos < min_without_last_token) {
        min_without_last_token = ti->pos;
      }
      if (max_without_last_token == -1 ||
          ti->pos > max_without_last_token) {
        max_without_last_token = ti->pos;
        max_token_info = ti;
      }
    }
  } else {
    uint32_t i;
    uint32_t n = data->n_token_infos;
    for (i = 0; i < n; i++) {
      token_info *ti = data->token_infos[i];
      if (ti->must_last) {
        continue;
      }
      if (min_without_last_token == -1 ||
          ti->pos < min_without_last_token) {
        min_without_last_token = ti->pos;
      }
      if (max_without_last_token == -1 ||
          ti->pos > max_without_last_token) {
        max_without_last_token = ti->pos;
        max_token_info = ti;
      }
    }
  }
  if (!max_token_info) {
    return true;
  }

  int interval_without_last_token =
    max_without_last_token -
    min_without_last_token -
    (max_token_info->n_tokens_in_phrase - 1);
  if (data->additional_last_interval < 0) {
    return (interval_without_last_token <= data->max_interval);
  } else {
    return ((interval <=
             (data->max_interval + data->additional_last_interval)) &&
            (interval_without_last_token <= data->max_interval));
  }
}

grn_inline static bool
grn_ii_select_data_check_near_element_intervals(grn_ctx *ctx,
                                                grn_ii_select_data *data)
{
  if (!data->max_element_intervals) {
    return true;
  }

  uint32_t n_max_element_intervals =
    GRN_INT32_VECTOR_SIZE(data->max_element_intervals);
  if (n_max_element_intervals == 0) {
    return true;
  }

  if (data->mode == GRN_OP_NEAR ||
      data->mode == GRN_OP_NEAR_PHRASE ||
      data->mode == GRN_OP_NEAR_PHRASE_PRODUCT) {
    uint32_t i;
    uint32_t n = data->bt->n;
    bt_zap(data->check_element_intervals_btree);
    for (i = 0; i < n; i++) {
      bt_push(data->check_element_intervals_btree,
              data->bt->nodes[i].ti);
    }
    if (n > n_max_element_intervals + 1) {
      n = n_max_element_intervals + 1;
    }
    int32_t previous_pos = data->check_element_intervals_btree->min->pos;
    for (i = 1; i < n; i++) {
      bt_pop(data->check_element_intervals_btree);
      int32_t pos = data->check_element_intervals_btree->min->pos;
      int32_t max_element_interval =
        GRN_INT32_VALUE_AT(data->max_element_intervals, i - 1);
      if (max_element_interval >= 0 &&
          (pos - previous_pos) > max_element_interval) {
        return false;
      }
      previous_pos = pos;
    }
    return true;
  } else if (data->mode == GRN_OP_ORDERED_NEAR_PHRASE) {
    uint32_t i;
    uint32_t n = data->n_token_infos;
    if (n > n_max_element_intervals + 1) {
      n = n_max_element_intervals + 1;
    }
    int32_t previous_pos = data->token_infos[0]->pos;
    for (i = 1; i < n; i++) {
      int32_t pos = data->token_infos[i]->pos;
      int32_t max_element_interval =
        GRN_INT32_VALUE_AT(data->max_element_intervals, i - 1);
      if (max_element_interval >= 0 &&
          (pos - previous_pos) > max_element_interval) {
        return false;
      }
      previous_pos = pos;
    }
    return true;
  } else if (data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT) {
    uint32_t i;
    uint32_t n = data->n_phrase_groups;
    if (n > n_max_element_intervals + 1) {
      n = n_max_element_intervals + 1;
    }
    int32_t previous_pos = data->phrase_groups[0].btree->min->pos;
    for (i = 1; i < n; i++) {
      int32_t pos = data->phrase_groups[i].btree->min->pos;
      int32_t max_element_interval =
        GRN_INT32_VALUE_AT(data->max_element_intervals, i - 1);
      if (max_element_interval >= 0 &&
          (pos - previous_pos) > max_element_interval) {
        return false;
      }
      previous_pos = pos;
    }
    return true;
  } else {
    return false;
  }
}

grn_inline static bool
grn_ii_select_cursor_next_prepare(grn_ctx *ctx,
                                  grn_ii_select_cursor *cursor)
{
  grn_ii_select_data *data = &(cursor->data);
  uint32_t i;
  uint32_t n = data->n_token_infos;
  if (data->mode == GRN_OP_NEAR_PHRASE_PRODUCT ||
      data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT) {
    uint32_t min_rid = 0;
    uint32_t min_sid = 0;
    for (i = 0; i < n; i++) {
      token_info *ti = data->token_infos[i];
      if (ti->phrase_group_id == 0) {
        if ((ti->p->rid < data->next_rid) ||
            (ti->p->rid == data->next_rid && ti->p->sid < data->next_sid)) {
          continue;
        }
        if (min_rid == 0 ||
            ti->p->rid < min_rid ||
            (ti->p->rid == min_rid && ti->p->sid < min_sid)) {
          min_rid = ti->p->rid;
          min_sid = ti->p->sid;
        }
      } else {
        token_info_skip(ctx, ti, min_rid, min_sid);
      }
    }
    data->rid = min_rid;
    data->sid = min_sid;
    data->next_rid = data->rid;
    data->next_sid = data->sid + 1;
  } else {
    data->rid = data->token_infos[0]->p->rid;
    data->sid = data->token_infos[0]->p->sid;
    data->next_rid = data->rid;
    data->next_sid = data->sid + 1;
    for (i = 1; i < n; i++) {
      data->token_info = data->token_infos[i];
      if (token_info_skip(ctx,
                          data->token_info,
                          data->rid,
                          data->sid) != GRN_SUCCESS) {
        return false;
      }
      if (data->token_info->p->rid != data->rid ||
          data->token_info->p->sid != data->sid) {
        data->next_rid = data->token_info->p->rid;
        data->next_sid = data->token_info->p->sid;
        break;
      }
    }
    data->may_match = (i == data->n_token_infos);
  }
  return true;
}

grn_inline static bool
grn_ii_select_cursor_next_skip(grn_ctx *ctx,
                               grn_ii_select_cursor *cursor)
{
  grn_ii_select_data *data = &(cursor->data);
  if (data->mode == GRN_OP_NEAR_PHRASE_PRODUCT ||
      data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT) {
    bool skipped = false;
    uint32_t i;
    uint32_t n = data->n_token_infos;
    for (i = 0; i < n; i++) {
      token_info *ti = data->token_infos[i];
      if (ti->phrase_group_id != 0) {
        break;
      }
      if (token_info_skip(ctx,
                          ti,
                          data->next_rid,
                          data->next_sid) == GRN_SUCCESS) {
        skipped = true;
      }
    }
    return skipped;
  } else {
    return token_info_skip(ctx,
                           data->token_infos[0],
                           data->next_rid,
                           data->next_sid) == GRN_SUCCESS;
  }
}

grn_inline static bool
grn_ii_select_cursor_next_find_one_token(grn_ctx *ctx,
                                         grn_ii_select_cursor *cursor,
                                         const char *tag)
{
  grn_ii_select_data *data = &(cursor->data);
  token_info *ti = data->token_infos[0];
  data->start_pos = data->end_pos = data->pos = ti->p->pos;
  if (cursor->per_occurrence_mode) {
    data->n_occurrences = 1;
  } else {
    data->n_occurrences = ti->p->tf;
  }
  data->total_score = ti->p->weight + ti->cursors->bins[0]->weight;
  if (data->score_func) {
    GRN_RECORD_PUT(ctx,
                   &(data->record.terms),
                   ti->cursors->bins[0]->id);
    GRN_UINT32_PUT(ctx, &(data->record.term_weights), data->total_score);
    data->record.n_occurrences = data->n_occurrences;
    data->record.n_candidates = ti->size;
    data->record.n_tokens = ti->ntoken;
  }
  return true;
}

grn_inline static bool
grn_ii_select_cursor_next_find_near(grn_ctx *ctx,
                                    grn_ii_select_cursor *cursor,
                                    const char *tag)
{
  grn_ii_select_data *data = &(cursor->data);
  bt_zap(data->bt);
  bool need_check = true;
  if (data->mode == GRN_OP_NEAR_PHRASE ||
      data->mode == GRN_OP_ORDERED_NEAR_PHRASE) {
    uint32_t phrase_id;
    for (phrase_id = 0; phrase_id < data->n_phrases; phrase_id++) {
      if (!grn_ii_select_data_find_phrase(ctx,
                                          data,
                                          phrase_id,
                                          data->pos)) {
        need_check = false;
        break;
      }
      /* TODO: Can we update data->pos to reduce needless search? */
      bt_push(data->bt, data->token_info);
    }
  } else if (data->mode == GRN_OP_NEAR_PHRASE_PRODUCT ||
             data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT) {
    uint32_t i;
    uint32_t phrase_id = 0;
    for (i = 0; i < data->n_phrase_groups; i++) {
      phrase_group *group = &(data->phrase_groups[i]);
      bt_zap(group->btree);
      uint32_t end_phrase_id = phrase_id + group->n_phrases;
      bool have_phrase = false;
      for (; phrase_id < end_phrase_id; phrase_id++) {
        if (grn_ii_select_data_find_phrase(ctx,
                                           data,
                                           phrase_id,
                                           data->pos)) {
          have_phrase = true;
          bt_push(group->btree, data->token_info);
          /* TODO: Can we update data->pos to reduce needless search? */
        }
      }
      if (!have_phrase) {
        need_check = false;
        break;
      }
      bt_push(data->bt, group->btree->min);
    }
  } else {
    uint32_t i;
    uint32_t n = data->n_token_infos;
    for (i = 0; i < n; i++) {
      token_info *ti = data->token_infos[i];
      bt_push(data->bt, ti);
    }
  }
  if (!need_check) {
    return true;
  }

  for (;;) {
    data->token_info = data->bt->min;
    int32_t min = data->token_info->pos;
    int32_t max = data->bt->max->pos;
    if (min > max) {
      char ii_name[GRN_TABLE_MAX_KEY_SIZE];
      int ii_name_size;
      ii_name_size = grn_obj_name(ctx,
                                  (grn_obj *)(data->ii),
                                  ii_name,
                                  GRN_TABLE_MAX_KEY_SIZE);
      ERR(GRN_FILE_CORRUPT,
          "%s[%s] "
          "max position must be larger than min position: "
          "min:<%d> max:<%d> ii:<%.*s> string:<%.*s>",
          tag,
          grn_operator_to_string(data->mode),
          min, max,
          ii_name_size, ii_name,
          data->query_len,
          data->query);
      return false;
    }
    int32_t interval = max - min;
    if (data->mode == GRN_OP_NEAR_PHRASE ||
        data->mode == GRN_OP_ORDERED_NEAR_PHRASE ||
        data->mode == GRN_OP_NEAR_PHRASE_PRODUCT ||
        data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT) {
      interval -= (data->token_info->n_tokens_in_phrase - 1);
    }
    bool matched = false;
    if (data->mode == GRN_OP_ORDERED_NEAR_PHRASE) {
      matched = true;
      uint32_t i;
      uint32_t n = data->n_token_infos;
      int32_t pos = data->token_infos[0]->pos;
      for (i = 1; i < n; i++) {
        token_info *ti = data->token_infos[i];
        if (ti->pos < pos) {
          matched = false;
          break;
        }
        pos = ti->pos;
      }
      if (matched) {
        matched = grn_ii_select_data_is_matched_near_phrase(ctx,
                                                            data,
                                                            interval);
      }
    } else if (data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT) {
      matched = true;
      uint32_t i;
      uint32_t n = data->n_phrase_groups;
      int32_t pos = data->phrase_groups[0].btree->min->pos;
      for (i = 1; i < n; i++) {
        token_info *ti = data->phrase_groups[i].btree->min;
        if (ti->pos < pos) {
          matched = false;
          break;
        }
        pos = ti->pos;
      }
      if (matched) {
        matched = grn_ii_select_data_is_matched_near_phrase(ctx,
                                                            data,
                                                            interval);
      }
    } else if (data->bt->n_must_lasts > 0) {
      matched = (data->bt->n_must_lasts == 1 &&
                 data->bt->max->must_last &&
                 grn_ii_select_data_is_matched_near_phrase(ctx,
                                                           data,
                                                           interval));
    } else {
      matched = ((data->max_interval < 0) ||
                 (interval <= data->max_interval));
    }
    if (matched) {
      matched = grn_ii_select_data_check_near_element_intervals(ctx, data);
    }
    if (matched) {
      data->n_occurrences++;
      int32_t next_pos = max + 1;
      if (data->mode == GRN_OP_NEAR_PHRASE ||
          data->mode == GRN_OP_ORDERED_NEAR_PHRASE) {
        if (!grn_ii_select_data_find_phrase(ctx,
                                            data,
                                            data->token_info->phrase_id,
                                            next_pos)) {
          break;
        }
      } else if (data->mode == GRN_OP_NEAR_PHRASE_PRODUCT ||
                 data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT) {
        if (!grn_ii_select_data_find_phrase_product(ctx, data, next_pos)) {
          break;
        }
      } else {
        if (!grn_ii_select_skip_pos(ctx, data, next_pos)) {
          break;
        }
      }
    } else {
      if (data->mode == GRN_OP_NEAR_PHRASE ||
          data->mode == GRN_OP_ORDERED_NEAR_PHRASE) {
        int32_t next_pos = min + 1;
        if (!grn_ii_select_data_find_phrase(ctx,
                                            data,
                                            data->token_info->phrase_id,
                                            next_pos)) {
          break;
        }
      } else if (data->mode == GRN_OP_NEAR_PHRASE_PRODUCT ||
                 data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT) {
        int32_t next_pos = min + 1;
        if (!grn_ii_select_data_find_phrase_product(ctx, data, next_pos)) {
          break;
        }
      } else {
        int32_t next_pos = max - data->max_interval;
        if (next_pos <= min) {
          next_pos = min + 1;
        }
        if (!grn_ii_select_skip_pos(ctx, data, next_pos)) {
          break;
        }
      }
    }
    bt_reorder_min(data->bt);
    if ((data->mode == GRN_OP_NEAR_PHRASE ||
         data->mode == GRN_OP_ORDERED_NEAR_PHRASE ||
         data->mode == GRN_OP_NEAR_PHRASE_PRODUCT ||
         data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT) &&
        data->bt->min->pos == min) {
      break;
    }
  }
  return true;
}

grn_inline static bool
grn_ii_select_cursor_next_find(grn_ctx *ctx,
                               grn_ii_select_cursor *cursor,
                               const char *tag)
{
  grn_ii_select_data *data = &(cursor->data);
  uint32_t count = 0;
  int32_t score = 0;
  token_info **tis = data->token_infos;
  token_info **tie = data->token_infos + data->n_token_infos;
  token_info **tip;
  for (tip = tis; ; tip++) {
    if (tip == tie) { tip = tis; }
    data->token_info = *tip;
    if (!grn_ii_select_skip_pos(ctx, data, data->pos)) {
      break;
    }
    if (data->token_info->pos == (int32_t)(data->pos)) {
      if (count == 0) {
        data->start_pos = data->pos;
      }
      score +=
        data->token_info->p->weight +
        data->token_info->cursors->bins[0]->weight;
      count++;
      if ((int32_t)(data->token_info->p->pos) > data->end_pos) {
        data->end_pos = data->token_info->p->pos;
      }
    } else {
      score =
        data->token_info->p->weight +
        data->token_info->cursors->bins[0]->weight;
      count = 1;
      data->start_pos = data->pos = data->token_info->pos;
      data->end_pos = data->token_info->p->pos;
      if (data->n_occurrences == 0 && data->score_func) {
        GRN_BULK_REWIND(&(data->record.terms));
        GRN_BULK_REWIND(&(data->record.term_weights));
        data->record.n_candidates = 0;
        data->record.n_tokens = 0;
      }
    }
    if (data->n_occurrences == 0 && data->score_func) {
      GRN_RECORD_PUT(ctx,
                     &(data->record.terms),
                     data->token_info->cursors->bins[0]->id);
      GRN_UINT32_PUT(ctx,
                     &(data->record.term_weights),
                     data->token_info->p->weight +
                     data->token_info->cursors->bins[0]->weight);
      data->record.n_candidates += data->token_info->size;
      data->record.n_tokens += data->token_info->ntoken;
    }
    if (count == data->n_token_infos) {
      if ((int32_t)(data->token_info->p->pos) > data->end_pos) {
        data->end_pos = data->token_info->p->pos;
      }
      data->total_score += score;
      score = 0;
      count = 0;
      data->pos++;
      data->n_occurrences++;
      if (cursor->per_occurrence_mode) {
        break;
      }
    }
  }
  return true;
}

grn_ii_select_cursor_posting *
grn_ii_select_cursor_next(grn_ctx *ctx,
                          grn_ii_select_cursor *cursor)
{
  const char *tag = "[ii][select][cursor][next]";

  if (cursor->have_unshifted_posting) {
    cursor->have_unshifted_posting = false;
    return &(cursor->unshifted_posting);
  }

  if (cursor->done) {
    return NULL;
  }

  grn_ii_select_data *data = &(cursor->data);
  for (;;) {
    data->may_match = true;
    if (!grn_ii_select_cursor_next_prepare(ctx, cursor)) {
      goto exit;
    }
    float weight = get_weight(ctx, data);
    if (data->may_match && fpclassify(weight) == FP_ZERO) {
      data->may_match = false;
    }
    if (data->may_match) {
      if (data->op != GRN_OP_OR) {
        if (data->result_set) {
          grn_rset_posinfo pi = {data->rid, data->sid, 0};
          grn_id id = grn_hash_get(ctx,
                                   data->result_set,
                                   &pi,
                                   data->result_set->key_size,
                                   NULL);
          data->may_match = (id != GRN_ID_NIL);
        }
      }
    }
    if (!data->may_match) {
      if (!grn_ii_select_cursor_next_skip(ctx, cursor)) {
        goto exit;
      }
      continue;
    }

    data->start_pos = 0;
    data->end_pos = 0;
    data->total_score = 0;
    data->n_occurrences = 0;

    data->pos = 0;
    if (data->score_func) {
      GRN_BULK_REWIND(&(data->record.terms));
      GRN_BULK_REWIND(&(data->record.term_weights));
      data->record.n_candidates = 0;
      data->record.n_tokens = 0;
    }

    if (data->n_token_infos == 1) {
      if (!grn_ii_select_cursor_next_find_one_token(ctx, cursor, tag)) {
        goto exit;
      }
    } else if (data->mode == GRN_OP_NEAR ||
               data->mode == GRN_OP_NEAR_PHRASE ||
               data->mode == GRN_OP_ORDERED_NEAR_PHRASE ||
               data->mode == GRN_OP_NEAR_PHRASE_PRODUCT ||
               data->mode == GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT) {
      if (!grn_ii_select_cursor_next_find_near(ctx, cursor, tag)) {
        goto exit;
      }
    } else {
      if (!grn_ii_select_cursor_next_find(ctx, cursor, tag)) {
        goto exit;
      }
    }

    if (data->n_occurrences == 0) {
      if (!grn_ii_select_cursor_next_skip(ctx, cursor)) {
        goto exit;
      }
      continue;
    }

    double record_score;
    if (data->score_func) {
      data->record.id = data->rid;
      data->record.weight = weight;
      data->record.n_occurrences = data->n_occurrences;
      data->record.total_term_weights = data->total_score;
      record_score = data->score_func(ctx, &(data->record)) * (double)weight;
    } else {
      record_score = (data->n_occurrences + data->total_score) * (double)weight;
    }
    if (data->set_min_enable_for_and_query) {
      if (data->current_min == GRN_ID_NIL) {
        data->current_min = data->rid;
      }
    }

    cursor->posting.rid = data->rid;
    cursor->posting.sid = data->sid;
    cursor->posting.pos = data->pos;
    cursor->posting.start_pos = data->start_pos;
    cursor->posting.end_pos = data->end_pos;
    cursor->posting.tf = data->n_occurrences;
    cursor->posting.score = record_score;
    if (cursor->per_occurrence_mode) {
      if (token_info_skip_pos(ctx,
                              data->token_infos[0],
                              data->rid,
                              data->sid,
                              data->end_pos + 1) != GRN_SUCCESS) {
        cursor->done = true;
      }
    } else {
      if (!grn_ii_select_cursor_next_skip(ctx, cursor)) {
        cursor->done = true;
      }
    }
    return &(cursor->posting);
  }

exit :
  cursor->done = true;
  return NULL;
}

static void
grn_ii_select_cursor_unshift(grn_ctx *ctx,
                             grn_ii_select_cursor *cursor,
                             grn_ii_select_cursor_posting *posting)
{
  cursor->unshifted_posting = *posting;
  cursor->have_unshifted_posting = GRN_TRUE;
}

grn_ii *
grn_ii_select_cursor_get_ii(grn_ctx *ctx, grn_ii_select_cursor *cursor)
{
  return cursor->data.ii;
}

static void
grn_ii_parse_regexp_query_flush(grn_ctx *ctx,
                                grn_obj *parsed_strings,
                                grn_obj *parsed_n_following_characters,
                                grn_obj *string,
                                uint32_t *n_following_characters_start,
                                uint32_t *n_following_characters_end)
{
  if (GRN_TEXT_LEN(string) > 0) {
    grn_vector_add_element(ctx,
                           parsed_strings,
                           GRN_TEXT_VALUE(string),
                           GRN_TEXT_LEN(string),
                           0,
                           GRN_DB_TEXT);
    GRN_BULK_REWIND(string);
    GRN_UINT32_PUT(ctx,
                   parsed_n_following_characters,
                   *n_following_characters_start);
    GRN_UINT32_PUT(ctx,
                   parsed_n_following_characters,
                   *n_following_characters_end);
  }
  *n_following_characters_start = 0;
  *n_following_characters_end = 0;
}

static grn_rc
grn_ii_parse_regexp_query(grn_ctx *ctx,
                          const char *log_tag,
                          const char *string, unsigned int string_len,
                          grn_obj *parsed_strings,
                          grn_obj *parsed_n_following_characters)
{
  grn_bool escaping = GRN_FALSE;
  grn_bool in_paren = GRN_FALSE;
  const char *all_off_options = "?-mix:";
  size_t all_off_options_len = strlen(all_off_options);
  int nth_char = 0;
  const char *current = string;
  const char *string_end = string + string_len;
  grn_obj buffer;
  uint32_t n_following_characters_start = 0;
  uint32_t n_following_characters_end = 0;

  GRN_TEXT_INIT(&buffer, 0);
  while (current < string_end) {
    const char *target;
    int char_len;

    char_len = grn_charlen(ctx, current, string_end);
    if (char_len == 0) {
      GRN_OBJ_FIN(ctx, &buffer);
      ERR(GRN_INVALID_ARGUMENT,
          "%s invalid encoding character: <%.*s|%#x|>",
          log_tag,
          (int)(current - string), string,
          *current);
      return ctx->rc;
    }
    target = current;
    current += char_len;

    if (escaping) {
      escaping = GRN_FALSE;
      if (char_len == 1) {
        switch (*target) {
        case 'A' :
          if (nth_char == 0) {
            target = GRN_TOKENIZER_BEGIN_MARK_UTF8;
            char_len = GRN_TOKENIZER_BEGIN_MARK_UTF8_LEN;
          }
          break;
        case 'z' :
          if (current == string_end ||
              (in_paren &&
               grn_charlen(ctx, current, string_end) == 1 &&
               *current == ')' &&
               (current + 1) == string_end)) {
            target = GRN_TOKENIZER_END_MARK_UTF8;
            char_len = GRN_TOKENIZER_END_MARK_UTF8_LEN;
          }
          break;
        default :
          break;
        }
      }
    } else {
      if (n_following_characters_start > 0 &&
          (!(char_len == 1 && (*target == '.' || *target == '*')))) {
        grn_ii_parse_regexp_query_flush(ctx,
                                        parsed_strings,
                                        parsed_n_following_characters,
                                        &buffer,
                                        &n_following_characters_start,
                                        &n_following_characters_end);
      }

      if (char_len == 1) {
        if (*target == '\\') {
          escaping = GRN_TRUE;
          continue;
        } else if (*target == '(' &&
                   (size_t)(string_end - current) >= all_off_options_len &&
                   memcmp(current, all_off_options, all_off_options_len) == 0) {
          current += all_off_options_len;
          in_paren = GRN_TRUE;
          continue;
        } else if (*target == ')') {
          in_paren = GRN_FALSE;
          continue;
        } else if (*target == '.') {
          n_following_characters_start++;
          n_following_characters_end++;
          continue;
        } else if (*target == '*') {
          /* ".*" is only supported for now. */
          if (n_following_characters_start > 0) {
            n_following_characters_start--;
            n_following_characters_end--;
          }
          grn_ii_parse_regexp_query_flush(ctx,
                                          parsed_strings,
                                          parsed_n_following_characters,
                                          &buffer,
                                          &n_following_characters_start,
                                          &n_following_characters_end);
          continue;
        }
      }
    }

    GRN_TEXT_PUT(ctx, &buffer, target, char_len);
    nth_char++;
  }
  grn_ii_parse_regexp_query_flush(ctx,
                                  parsed_strings,
                                  parsed_n_following_characters,
                                  &buffer,
                                  &n_following_characters_start,
                                  &n_following_characters_end);
  size_t parsed_n_following_characters_size =
    GRN_UINT32_VECTOR_SIZE(parsed_n_following_characters);
  if (parsed_n_following_characters_size > 0 &&
      (GRN_UINT32_VALUE_AT(parsed_n_following_characters,
                           parsed_n_following_characters_size - 1) > 0)) {
    /* 0 means no limit for now. It may be changed when we implement full
     * the number of following characters range support. */
    GRN_UINT32_VALUE_AT(parsed_n_following_characters,
                        parsed_n_following_characters_size - 1) = 0;
    GRN_TEXT_SET(ctx,
                 &buffer,
                 GRN_TOKENIZER_END_MARK_UTF8,
                 GRN_TOKENIZER_END_MARK_UTF8_LEN);
    grn_ii_parse_regexp_query_flush(ctx,
                                    parsed_strings,
                                    parsed_n_following_characters,
                                    &buffer,
                                    &n_following_characters_start,
                                    &n_following_characters_end);
  }
  GRN_OBJ_FIN(ctx, &buffer);

  return GRN_SUCCESS;
}

typedef struct {
  grn_ii_select_cursor *cursor;
  uint32_t n_following_characters_start;
  uint32_t n_following_characters_end;
  uint32_t next_start_pos_offset;
} grn_ii_select_regexp_chunk;

static grn_rc
grn_ii_select_regexp(grn_ctx *ctx, grn_ii *ii,
                     const char *string, unsigned int string_len,
                     grn_hash *s, grn_operator op, grn_select_optarg *optarg)
{
  grn_rc rc;
  grn_obj parsed_strings;
  grn_obj parsed_n_following_characters;
  unsigned int n_parsed_strings;

  GRN_TEXT_INIT(&parsed_strings, GRN_OBJ_VECTOR);
  GRN_UINT32_INIT(&parsed_n_following_characters, GRN_OBJ_VECTOR);
  rc = grn_ii_parse_regexp_query(ctx, "[ii][select][regexp]",
                                 string, string_len,
                                 &parsed_strings,
                                 &parsed_n_following_characters);
  if (rc != GRN_SUCCESS) {
    GRN_OBJ_FIN(ctx, &parsed_strings);
    return rc;
  }

  if (optarg) {
    optarg->mode = GRN_OP_EXACT;
  }

  n_parsed_strings = grn_vector_size(ctx, &parsed_strings);
  if (n_parsed_strings == 1 &&
      GRN_UINT32_VALUE_AT(&parsed_n_following_characters, 0) == 0) {
    const char *parsed_string;
    unsigned int parsed_string_len;
    parsed_string_len = grn_vector_get_element(ctx,
                                               &parsed_strings,
                                               0,
                                               &parsed_string,
                                               NULL,
                                               NULL);
    rc = grn_ii_select(ctx, ii,
                       parsed_string,
                       parsed_string_len,
                       s, op, optarg);
  } else {
    unsigned int i;
    grn_ii_select_regexp_chunk *chunks;
    grn_bool have_error = GRN_FALSE;

    chunks = GRN_CALLOC(sizeof(grn_ii_select_regexp_chunk) * n_parsed_strings);
    for (i = 0; i < n_parsed_strings; i++) {
      const char *parsed_string;
      unsigned int parsed_string_len;
      parsed_string_len = grn_vector_get_element(ctx,
                                                 &parsed_strings,
                                                 i,
                                                 &parsed_string,
                                                 NULL,
                                                 NULL);
      chunks[i].cursor = grn_ii_select_cursor_open(ctx,
                                                   ii,
                                                   parsed_string,
                                                   parsed_string_len,
                                                   optarg);
      if (!chunks[i].cursor) {
        have_error = GRN_TRUE;
        break;
      }
      grn_ii_select_cursor_set_per_occurrence_mode(ctx,
                                                   chunks[i].cursor,
                                                   true);
      chunks[i].n_following_characters_start =
        GRN_UINT32_VALUE_AT(&parsed_n_following_characters, i * 2);
      chunks[i].n_following_characters_end =
        GRN_UINT32_VALUE_AT(&parsed_n_following_characters, i * 2 + 1);
      uint32_t next_start_pos_offset = chunks[i].n_following_characters_start;
      if (chunks[i].n_following_characters_start > 0) {
        size_t n_characters = 0;
        const char *current = parsed_string;
        const char *parsed_string_end = parsed_string + parsed_string_len;
        while (current < parsed_string_end) {
          int char_len = grn_charlen(ctx, current, parsed_string_end);
          if (char_len == 0) { /* must not happen */
            break;
          }
          current += char_len;
          n_characters++;
        }
        if (n_characters > 1) {
          /* text: "abcd", query: "a." case:
           *   tokens: "ab", "bc", "cd", "d"
           *   n_characters: 1
           *   n_following_characters: 1
           *   There are no token that is ignored after the "ab" token.
           *
           * text: "abcd", query: "ab." case:
           *   tokens: "ab", "bc", "cd", "d"
           *   n_characters: 2
           *   n_following_characters: 1
           *   The "bc" token must be ignored because the cursor returns
           *   the position for the "ab" token.
           */
          next_start_pos_offset++;
        }
        next_start_pos_offset++;
      }
      chunks[i].next_start_pos_offset = next_start_pos_offset;
    }

    while (!have_error) {
      grn_ii_select_cursor_posting *posting;

      posting = grn_ii_select_cursor_next(ctx, chunks[0].cursor);
      if (!posting) {
        break;
      }

      uint32_t pos = posting->end_pos;
      uint32_t n_following_characters_start =
        chunks[0].n_following_characters_start;
      uint32_t n_following_characters_end =
        chunks[0].n_following_characters_end;
      uint32_t next_start_pos = pos + chunks[0].next_start_pos_offset;
      for (i = 1; i < n_parsed_strings; i++) {
        grn_ii_select_cursor_posting *posting_i;

        for (;;) {
          posting_i = grn_ii_select_cursor_next(ctx, chunks[i].cursor);
          if (!posting_i) {
            break;
          }

          if (posting_i->rid > posting->rid) {
            grn_ii_select_cursor_unshift(ctx, chunks[i].cursor, posting_i);
            break;
          }
          if (posting_i->sid > posting->sid) {
            grn_ii_select_cursor_unshift(ctx, chunks[i].cursor, posting_i);
            break;
          }
          if (posting_i->rid == posting->rid &&
              posting_i->sid == posting->sid) {
            if (n_following_characters_start == 0) {
              if (posting_i->start_pos > pos) {
                grn_ii_select_cursor_unshift(ctx, chunks[i].cursor, posting_i);
                break;
              }
            } else {
              if (posting_i->start_pos >= next_start_pos) {
                grn_ii_select_cursor_unshift(ctx, chunks[i].cursor, posting_i);
                break;
              }
            }
          }
        }

        if (!posting_i) {
          break;
        }
        if (posting_i->rid != posting->rid) {
          break;
        }
        if (posting_i->sid != posting->sid) {
          break;
        }
        if (n_following_characters_start > 0) {
          if (n_following_characters_end == 0) { /* 0 means no limit for now. */
            if (posting_i->start_pos < next_start_pos) {
              break;
            }
          } else {
            if (posting_i->start_pos != next_start_pos) {
              break;
            }
          }
        }

        pos = posting_i->end_pos;
        n_following_characters_start = chunks[i].n_following_characters_start;
        n_following_characters_end = chunks[i].n_following_characters_end;
        next_start_pos = pos + chunks[i].next_start_pos_offset;
      }

      if (i == n_parsed_strings && n_following_characters_start == 0) {
        grn_rset_posinfo pi = {posting->rid, posting->sid, pos};
        double record_score = 1.0;
        res_add(ctx, s, &pi, record_score, op);
      }
    }

    for (i = 0; i < n_parsed_strings; i++) {
      if (chunks[i].cursor) {
        grn_ii_select_cursor_close(ctx, chunks[i].cursor);
      }
    }
    GRN_FREE(chunks);
  }
  GRN_OBJ_FIN(ctx, &parsed_strings);
  GRN_OBJ_FIN(ctx, &parsed_n_following_characters);

  if (optarg) {
    optarg->mode = GRN_OP_REGEXP;
  }

  return rc;
}

typedef struct {
  uint32_t n_occurs;
  double score;
} grn_ii_quorum_match_record_data;

grn_rc
grn_ii_quorum_match(grn_ctx *ctx, grn_ii *ii, grn_ii_select_data *data)
{
  size_t record_key_size;
  grn_hash *n_occurs;
  grn_token_cursor *token_cursor;
  int ii_cursor_flags = 0;

  record_key_size = sizeof(grn_id);
  if (ii->header.common->flags & GRN_OBJ_WITH_SECTION) {
    record_key_size += sizeof(uint32_t);
    ii_cursor_flags |= GRN_OBJ_WITH_SECTION;
  }

  n_occurs = grn_hash_create(ctx,
                             NULL,
                             record_key_size,
                             sizeof(grn_ii_quorum_match_record_data),
                             0);
  if (!n_occurs) {
    return GRN_NO_MEMORY_AVAILABLE;
  }

  token_cursor = grn_ii_select_data_open_token_cursor(ctx,
                                                      data,
                                                      data->query,
                                                      data->query_len,
                                                      GRN_TOKENIZE_GET);
  if (!token_cursor) {
    grn_rc rc = ctx->rc;
    char ii_name[GRN_TABLE_MAX_KEY_SIZE];
    int ii_name_len;
    char errbuf[GRN_CTX_MSGSIZE];

    if (rc == GRN_SUCCESS) {
      rc = GRN_UNKNOWN_ERROR;
    }
    ii_name_len = grn_obj_name(ctx,
                               (grn_obj *)ii,
                               ii_name, GRN_TABLE_MAX_KEY_SIZE);
    grn_strcpy(errbuf, GRN_CTX_MSGSIZE, ctx->errbuf);
    ERR(rc,
        "[ii][quorum-match] failed to create token cursor: <%.*s>: <%.*s>%s%s",
        ii_name_len, ii_name,
        data->query_len, data->query,
        errbuf[0] ? ": " : "",
        errbuf[0] ? errbuf : "");
    grn_hash_close(ctx, n_occurs);
    return rc;
  }
  while (token_cursor->status != GRN_TOKEN_CURSOR_DONE &&
         token_cursor->status != GRN_TOKEN_CURSOR_DONE_SKIP) {
    grn_id tid;
    if ((tid = grn_token_cursor_next(ctx, token_cursor)) != GRN_ID_NIL) {
      grn_ii_cursor *cursor;
      cursor = grn_ii_cursor_open(ctx, ii, tid,
                                  GRN_ID_NIL, GRN_ID_MAX, ii->n_elements,
                                  ii_cursor_flags);
      while (grn_ii_cursor_next(ctx, cursor)) {
        grn_ii_quorum_match_record_data *record_data;

        data->rid = cursor->post->rid;
        data->sid = cursor->post->sid;
        float weight = get_weight(ctx, data);
        if (fpclassify(weight) == FP_ZERO) {
          continue;
        }
        if (grn_hash_add(ctx, n_occurs,
                         cursor->post,
                         record_key_size,
                         (void **)&record_data,
                         NULL)) {
          record_data->n_occurs++;
          record_data->score += weight;
        }
      }
      grn_ii_cursor_close(ctx, cursor);
    }
  }
  grn_token_cursor_close(ctx, token_cursor);

  {
    grn_rset_posinfo posinfo;
    grn_hash_cursor *cursor;

    memset(&posinfo, 0, sizeof(grn_rset_posinfo));
    cursor = grn_hash_cursor_open(ctx, n_occurs, NULL, 0, NULL, 0, 0, -1, 0);
    if (!cursor) {
      grn_rc rc = ctx->rc;
      char ii_name[GRN_TABLE_MAX_KEY_SIZE];
      int ii_name_len;
      char errbuf[GRN_CTX_MSGSIZE];

      if (rc == GRN_SUCCESS) {
        rc = GRN_UNKNOWN_ERROR;
      }
      ii_name_len = grn_obj_name(ctx,
                                 (grn_obj *)ii,
                                 ii_name, GRN_TABLE_MAX_KEY_SIZE);
      grn_strcpy(errbuf, GRN_CTX_MSGSIZE, ctx->errbuf);
      ERR(rc,
          "[ii][quorum-match] failed to create count cursor: <%.*s>: <%.*s>%s%s",
          ii_name_len, ii_name,
          data->query_len, data->query,
          errbuf[0] ? ": " : "",
          errbuf[0] ? errbuf : "");
      grn_hash_close(ctx, n_occurs);
      return rc;
    }
    {
      const uint32_t quorum_threshold = data->optarg->quorum_threshold;
      while (grn_hash_cursor_next(ctx, cursor) != GRN_ID_NIL) {
        grn_posting *posting;
        grn_ii_quorum_match_record_data *record_data;

        grn_hash_cursor_get_key_value(ctx, cursor,
                                      (void **)&posting,
                                      NULL,
                                      (void **)&record_data);
        if (record_data->n_occurs >= quorum_threshold) {
          double score = record_data->score;
          grn_memcpy(&posinfo, posting, record_key_size);
          if (data->score_func) {
            data->record.id = posting->rid;
            data->record.weight = score / record_data->n_occurs;
            data->record.n_occurrences = record_data->n_occurs;
            data->record.total_term_weights = data->record.weight;
            score = data->score_func(ctx, &(data->record)) * data->record.weight;
          }
          res_add(ctx, data->result_set, &posinfo, score, data->op);
        }
      }
    }
    grn_hash_cursor_close(ctx, cursor);
  }
  grn_hash_close(ctx, n_occurs);
  grn_ii_resolve_sel_and(ctx, data->result_set, data->op);

  return GRN_SUCCESS;
}

static bool
grn_ii_select_sequential_search_reference_should_use(grn_ctx *ctx,
                                                     grn_ii_select_data *data)
{
  int n_sources;

  if (grn_ii_select_too_many_index_match_ratio_reference < 0.0) {
    return false;
  }

  if (data->op != GRN_OP_AND) {
    return false;
  }

  if (data->mode != GRN_OP_EXACT) {
    return false;
  }

  n_sources = DB_OBJ(data->ii)->source_size / sizeof(grn_id);
  if (n_sources == 0) {
    return false;
  }

  {
    grn_obj *tokenizer;
    grn_table_get_info(ctx, data->lexicon, NULL, NULL, &tokenizer, NULL, NULL);
    if (tokenizer) {
      return false;
    }
  }

  {
    int i;
    grn_id *source_ids = DB_OBJ(data->ii)->source;

    for (i = 0; i < n_sources; i++) {
      grn_id source_id = source_ids[i];
      grn_obj *source;

      source = grn_ctx_at(ctx, source_id);
      if (!source) {
        return false;
      }
      const bool is_reference_column = grn_obj_is_reference_column(ctx, source);
      grn_obj_unref(ctx, source);
      if (!is_reference_column) {
        return false;
      }
    }
  }

  {
    uint32_t n_existing_records = GRN_HASH_SIZE(data->result_set);
    uint32_t i;
    for (i = 0; i < data->n_token_infos; i++) {
      token_info *info = data->token_infos[i];
      if (n_existing_records <=
          (info->size * grn_ii_select_too_many_index_match_ratio_reference)) {
        grn_obj reason;
        GRN_TEXT_INIT(&reason, 0);
        grn_text_printf(ctx, &reason,
                        "enough filtered and "
                        "index search will match many records: "
                        "%u <= %.2f: "
                        "n-existing-records:%u "
                        "estimated-size:%u "
                        "ratio:%.2f%%",
                        n_existing_records,
                        info->size *
                        grn_ii_select_too_many_index_match_ratio_reference,
                        n_existing_records,
                        info->size,
                        grn_ii_select_too_many_index_match_ratio_reference * 100);
        GRN_TEXT_PUTC(ctx, &reason, '\0');
        grn_report_index_not_used(ctx,
                                  "[ii][select]",
                                  "[reference]",
                                  (grn_obj *)(data->ii),
                                  GRN_TEXT_VALUE(&reason));
        GRN_OBJ_FIN(ctx, &reason);
        return true;
      }
    }
    return false;
  }
}

static bool
grn_ii_select_sequential_search_reference(grn_ctx *ctx,
                                          grn_ii_select_data *data)
{
  const grn_id query_id = data->token_infos[0]->cursors[0].bins[0]->id;
  const grn_id lexicon_id = DB_OBJ(data->ii->lexicon)->id;
  grn_id *source_ids = DB_OBJ(data->ii)->source;
  const size_t n_sources = DB_OBJ(data->ii)->source_size / sizeof(grn_id);
  size_t i;
  for (i = 0; i < n_sources; i++) {
    const grn_id source_id = source_ids[i];
    grn_obj *source = grn_ctx_at(ctx, source_id);

    grn_obj value;
    switch (source->header.flags & GRN_OBJ_COLUMN_TYPE_MASK) {
    case GRN_OBJ_COLUMN_SCALAR :
      GRN_RECORD_INIT(&value, 0, lexicon_id);
      break;
    case GRN_OBJ_COLUMN_VECTOR :
      GRN_RECORD_INIT(&value, GRN_OBJ_VECTOR, lexicon_id);
      break;
    default :
      grn_obj_unref(ctx, source);
      return false;
    }

    GRN_HASH_EACH_BEGIN(ctx, data->result_set, cursor, id) {
      void *key;
      grn_hash_cursor_get_key(ctx, cursor, &key);
      grn_id source_table_id = *((grn_id *)key);
      GRN_BULK_REWIND(&value);
      grn_obj_get_value(ctx, source, source_table_id, &value);
      switch (value.header.type) {
      case GRN_BULK :
        if (GRN_RECORD_VALUE(&value) == query_id) {
          grn_rset_posinfo info;
          info.rid = source_table_id;
          info.sid = i + 1;
          info.pos = 0;
          data->rid = info.rid;
          data->sid = info.sid;
          float score = get_weight(ctx, data);
          res_add(ctx, data->result_set, &info, score, data->op);
        }
        break;
      case GRN_UVECTOR :
        {
          uint32_t n_elements = grn_vector_size(ctx, &value);
          uint32_t j;
          uint32_t n_founds = 0;
          for (j = 0; j < n_elements; j++) {
            if (GRN_RECORD_VALUE_AT(&value, j) == query_id) {
              n_founds++;
            }
          }
          if (n_founds > 0) {
            grn_rset_posinfo info;
            info.rid = source_table_id;
            info.sid = i + 1;
            info.pos = 0;
            data->rid = info.rid;
            data->sid = info.sid;
            float score = get_weight(ctx, data);
            res_add(ctx, data->result_set, &info, score * n_founds, data->op);
          }
        }
        break;
      default :
        break;
      }
    } GRN_HASH_EACH_END(ctx, cursor);
    GRN_OBJ_FIN(ctx, &value);
    grn_obj_unref(ctx, source);
  }

  return true;
}

#ifdef GRN_II_SELECT_ENABLE_SEQUENTIAL_SEARCH_TEXT
static bool
grn_ii_select_sequential_search_text_should_use(grn_ctx *ctx,
                                                grn_ii_select_data *data)
{
  if (grn_ii_select_too_many_index_match_ratio_text < 0.0) {
    return false;
  }

  if (data->op != GRN_OP_AND) {
    return false;
  }

  if (data->mode != GRN_OP_EXACT) {
    return false;
  }

  size_t n_sources = DB_OBJ(data->ii)->source_size / sizeof(grn_id);
  if (n_sources == 0) {
    return false;
  }

  {
    size_t i;
    grn_id *source_ids = DB_OBJ(data->ii)->source;

    for (i = 0; i < n_sources; i++) {
      grn_id source_id = source_ids[i];
      grn_obj *source;

      source = grn_ctx_at(ctx, source_id);
      if (!source) {
        return false;
      }
      grn_id value_type_id;
      if (grn_obj_is_table(ctx, source)) {
        value_type_id = source->header.domain;
      } else {
        value_type_id = grn_obj_get_range(ctx, source);
      }
      const bool is_text_family = grn_type_id_is_text_family(ctx, value_type_id);;
      grn_obj_unref(ctx, source);
      if (!is_text_family) {
        return false;
      }
    }
  }

  {
    uint32_t n_existing_records = GRN_HASH_SIZE(data->result_set);
    uint32_t i;
    for (i = 0; i < data->n_token_infos; i++) {
      token_info *info = data->token_infos[i];
      if (n_existing_records <=
          (info->size * grn_ii_select_too_many_index_match_ratio_text)) {
        grn_obj reason;
        GRN_TEXT_INIT(&reason, 0);
        grn_text_printf(ctx, &reason,
                        "enough filtered and "
                        "index search will match many records: "
                        "%u <= %.2f: "
                        "n-existing-records:%u "
                        "estimated-size:%u "
                        "ratio:%.2f%%",
                        n_existing_records,
                        info->size *
                        grn_ii_select_too_many_index_match_ratio_text,
                        n_existing_records,
                        info->size,
                        grn_ii_select_too_many_index_match_ratio_text * 100);
        GRN_TEXT_PUTC(ctx, &reason, '\0');
        grn_report_index_not_used(ctx,
                                  "[ii][select]",
                                  "[text]",
                                  (grn_obj *)(data->ii),
                                  GRN_TEXT_VALUE(&reason));
        GRN_OBJ_FIN(ctx, &reason);
        return true;
      }
    }
    return false;
  }
}

static void
grn_ii_select_sequential_search_text_body(grn_ctx *ctx,
                                          grn_ii_select_data *data,
                                          grn_encoding encoding,
                                          OnigRegex regex)
{
  grn_obj buffer;
  GRN_TEXT_INIT(&buffer, 0);
  grn_id *source_ids = DB_OBJ(data->ii)->source;
  const size_t n_sources = DB_OBJ(data->ii)->source_size / sizeof(grn_id);
  size_t i;
  for (i = 0; i < n_sources; i++) {
    const grn_id source_id = source_ids[i];
    grn_obj *source = grn_ctx_at(ctx, source_id);
    const bool source_is_table = grn_obj_is_table(ctx, source);
    GRN_HASH_EACH_BEGIN(ctx, data->result_set, cursor, id) {
      void *key;
      grn_hash_cursor_get_key(ctx, cursor, &key);
      grn_id source_table_id = *((grn_id *)key);
      GRN_BULK_REWIND(&buffer);
      if (source_is_table) {
        grn_table_get_key2(ctx, source, source_table_id, &buffer);
      } else {
        grn_obj_get_value(ctx, source, source_table_id, &buffer);
      }

      OnigPosition position;
      grn_obj *value;
      const char *normalized_value;
      unsigned int normalized_value_length;
      value = grn_string_open_(ctx,
                               GRN_TEXT_VALUE(&buffer),
                               GRN_TEXT_LEN(&buffer),
                               data->ii->lexicon,
                               0,
                               encoding);
      grn_string_get_normalized(ctx, value,
                                &normalized_value, &normalized_value_length,
                                NULL);
      position = onig_search(regex,
                             normalized_value,
                             normalized_value + normalized_value_length,
                             normalized_value,
                             normalized_value + normalized_value_length,
                             NULL,
                             0);
      if (position != ONIG_MISMATCH) {
        grn_rset_posinfo info;
        info.rid = source_table_id;
        info.sid = i + 1;
        info.pos = 0;
        data->rid = info.rid;
        data->sid = info.rid;
        float score = get_weight(ctx, data);
        res_add(ctx, data->result_set, &info, score, data->op);
      }
      grn_obj_unlink(ctx, value);
    } GRN_HASH_EACH_END(ctx, cursor);
    grn_obj_unref(ctx, source);
  }
  GRN_OBJ_FIN(ctx, &buffer);
}

static bool
grn_ii_select_sequential_search_text(grn_ctx *ctx,
                                     grn_ii_select_data *data)
{
  bool processed = false;

  {
    grn_encoding encoding;
    grn_table_get_info(ctx,
                       data->ii->lexicon,
                       NULL,
                       &encoding,
                       NULL,
                       NULL,
                       NULL);
    int nflags = 0;
    grn_obj *query = grn_string_open_(ctx,
                                      data->query,
                                      data->query_len,
                                      data->ii->lexicon,
                                      nflags,
                                      encoding);
    const char *normalized_query;
    unsigned int normalized_query_length;
    grn_string_get_normalized(ctx, query,
                              &normalized_query, &normalized_query_length,
                              NULL);
    {
      OnigRegex regex;
      regex = grn_onigmo_new(ctx,
                             normalized_query,
                             normalized_query_length,
                             ONIG_OPTION_NONE,
                             ONIG_SYNTAX_ASIS,
                             "[ii][select][sequential]");
      if (regex) {
        grn_ii_select_sequential_search_text_body(ctx, data, encoding, regex);
        onig_free(regex);
        processed = true;
      } else {
        processed = false;
      }
    }
    grn_obj_unlink(ctx, query);
  }

  return processed;
}
#endif

static bool
grn_ii_select_sequential_search(grn_ctx *ctx,
                                grn_ii_select_data *data)
{
  if (grn_ii_select_sequential_search_reference_should_use(ctx, data)) {
    return grn_ii_select_sequential_search_reference(ctx, data);
  }
#ifdef GRN_II_SELECT_ENABLE_SEQUENTIAL_SEARCH_TEXT
  else if (grn_ii_select_sequential_search_text_should_use(ctx, data)) {
    return grn_ii_select_sequential_search_text(ctx, data);
  }
#endif

  return false;
}

grn_rc
grn_ii_select(grn_ctx *ctx, grn_ii *ii,
              const char *string, unsigned int string_len,
              grn_hash *s, grn_operator op, grn_select_optarg *optarg)
{
  const char *tag = "[ii][select]";
  int rep, orp;

  if (!ii) {
    return GRN_INVALID_ARGUMENT;
  }

  grn_ii_select_cursor cursor;
  grn_ii_select_data *data;
  data = &(cursor.data);
  data->ii = ii;
  data->lexicon = data->ii->lexicon;
  if (!data->lexicon || !s) { return GRN_INVALID_ARGUMENT; }

  grn_selector_data_current_set_default_tag_raw(ctx, string, string_len);

  data->query = string;
  data->query_len = string_len;
  data->result_set = s;
  data->op = op;
  grn_ii_select_data_init(ctx, data, optarg);
  if (data->mode == GRN_OP_SIMILAR) {
    return grn_ii_similar_search_internal(ctx, data);
  }
  if (data->mode == GRN_OP_TERM_EXTRACT) {
    return grn_ii_term_extract_internal(ctx, data);
  }
  if (data->mode == GRN_OP_REGEXP) {
    return grn_ii_select_regexp(ctx, ii, string, string_len, s, op, optarg);
  }
  if (data->mode == GRN_OP_QUORUM) {
    return grn_ii_quorum_match(ctx, ii, data);
  }
  /* todo : support subrec
  rep = (s->record_unit == GRN_REC_POSITION || s->subrec_unit == GRN_REC_POSITION);
  orp = (s->record_unit == GRN_REC_POSITION || op == GRN_OP_OR);
  */
  rep = 0;
  orp = op == GRN_OP_OR;
  if (!grn_ii_select_data_init_token_infos(ctx, data, tag)) {
    goto exit;
  }
  if (grn_logger_pass(ctx, GRN_LOG_INFO)) {
    if (grn_type_id_is_text_family(ctx, ii->lexicon->header.domain)) {
      GRN_LOG(ctx,
              GRN_LOG_INFO,
              "%s n=%d (%.*s)",
              tag,
              data->n_token_infos,
              string_len, string);
    } else {
      grn_obj inspected;
      GRN_TEXT_INIT(&inspected, 0);
      grn_inspect_key(ctx, &inspected, ii->lexicon, string, string_len);
      GRN_LOG(ctx, GRN_LOG_INFO,
              "%s n=%d (%.*s)",
              tag,
              data->n_token_infos,
              (int)GRN_TEXT_LEN(&inspected),
              GRN_TEXT_VALUE(&inspected));
      GRN_OBJ_FIN(ctx, &inspected);
    }
  }
  /* todo : array as result
  if (n == 1 && (*tis)->cursors->n_entries == 1 && op == GRN_OP_OR
      && !GRN_HASH_SIZE(s) && !s->garbages
      && s->record_unit == GRN_REC_DOCUMENT && !s->max_n_subrecs
      && grn_ii_max_section(ii) == 1) {
    grn_ii_cursor *c = (*tis)->cursors->bins[0];
    if ((rc = grn_hash_array_init(s, (*tis)->size + 32768))) { goto exit; }
    do {
      grn_rset_recinfo *ri;
      grn_posting *p = c->post;
      if ((weight = get_weight(ctx, s, p->rid, p->sid, wvm, optarg))) {
        GRN_HASH_INT_ADD(s, p, ri);
        ri->score = (p->tf + p->score) * weight;
        ri->n_subrecs = 1;
      }
    } while (grn_ii_cursor_next(ctx, c));
    goto exit;
  }
  */
  if (grn_ii_select_sequential_search(ctx, data)) {
    goto exit;
  }

  grn_ii_select_cursor_init_internal(ctx, &cursor);
  grn_result_set_add_ii_select_cursor(ctx, s, &cursor, op);

exit :
  if (!data->only_skip_token) {
    grn_ii_resolve_sel_and(ctx, s, op);
  }

  grn_ii_select_data_fin(ctx, data);

  //  grn_hash_cursor_clear(r);
#ifdef DEBUG
  {
    uint32_t i;
    uint32_t n_segments = ii->seg->header->max_segment;
    uint32_t n_nrefs = 0;
    grn_io_mapinfo *info = ii->seg->maps;
    for (i = 0; i < n_segments; i++, info++) {
      if (info->nref > 0) {
        n_nrefs++;
      }
    }
    GRN_LOG(ctx, GRN_LOG_INFO, "n_nrefs=%u", n_nrefs);
  }
#endif /* DEBUG */
  return ctx->rc;
}

static void
grn_select_optarg_init_by_search_optarg(grn_ctx *ctx,
                                        grn_select_optarg *select_optarg,
                                        grn_search_optarg *search_optarg)
{
  memset(select_optarg, 0, sizeof(grn_select_optarg));
  select_optarg->mode = GRN_OP_EXACT;
  if (!search_optarg) {
    return;
  }

  switch (search_optarg->mode) {
  case GRN_OP_NEAR :
  case GRN_OP_NEAR_NO_OFFSET :
    select_optarg->mode = search_optarg->mode;
    select_optarg->max_interval = search_optarg->max_interval;
    select_optarg->max_element_intervals = search_optarg->max_element_intervals;
    break;
  case GRN_OP_NEAR_PHRASE :
  case GRN_OP_ORDERED_NEAR_PHRASE :
  case GRN_OP_NEAR_PHRASE_PRODUCT :
  case GRN_OP_ORDERED_NEAR_PHRASE_PRODUCT :
    select_optarg->mode = search_optarg->mode;
    select_optarg->max_interval = search_optarg->max_interval;
    select_optarg->additional_last_interval =
      search_optarg->additional_last_interval;
    select_optarg->max_element_intervals = search_optarg->max_element_intervals;
    break;
  case GRN_OP_SIMILAR :
    select_optarg->mode = search_optarg->mode;
    select_optarg->similarity_threshold =
      search_optarg->similarity_threshold;
    break;
  case GRN_OP_REGEXP :
    select_optarg->mode = search_optarg->mode;
    break;
  case GRN_OP_FUZZY :
    select_optarg->mode = search_optarg->mode;
    select_optarg->fuzzy = search_optarg->fuzzy;
    break;
  case GRN_OP_QUORUM :
    select_optarg->mode = search_optarg->mode;
    select_optarg->quorum_threshold = search_optarg->quorum_threshold;
    break;
  default :
    break;
  }
  if (search_optarg->vector_size != 0) {
    select_optarg->weight_vector = search_optarg->weight_vector;
    select_optarg->weight_vector_float = search_optarg->weight_vector_float;
    select_optarg->vector_size = search_optarg->vector_size;
    select_optarg->weight_float = search_optarg->weight_float;
  }
  select_optarg->scorer = search_optarg->scorer;
  select_optarg->scorer_args_expr = search_optarg->scorer_args_expr;
  select_optarg->scorer_args_expr_offset =
    search_optarg->scorer_args_expr_offset;
  select_optarg->match_info = &(search_optarg->match_info);
  select_optarg->query_options = search_optarg->query_options;
}

static uint32_t
grn_ii_estimate_size_for_query_regexp(grn_ctx *ctx, grn_ii *ii,
                                      const char *query, unsigned int query_len,
                                      grn_search_optarg *optarg)
{
  grn_rc rc;
  grn_obj parsed_strings;
  grn_obj parsed_n_following_characters;
  uint32_t size;

  GRN_TEXT_INIT(&parsed_strings, GRN_OBJ_VECTOR);
  GRN_UINT32_INIT(&parsed_n_following_characters, GRN_OBJ_VECTOR);
  rc = grn_ii_parse_regexp_query(ctx, "[ii][estimate-size][query][regexp]",
                                 query, query_len,
                                 &parsed_strings,
                                 &parsed_n_following_characters);
  if (rc != GRN_SUCCESS) {
    GRN_OBJ_FIN(ctx, &parsed_strings);
    return 0;
  }

  if (optarg) {
    optarg->mode = GRN_OP_EXACT;
  }

  unsigned int i;
  unsigned int n_parsed_strings = grn_vector_size(ctx, &parsed_strings);
  for (i = 0; i < n_parsed_strings; i++) {
    const char *parsed_string;
    unsigned int parsed_string_len;
    parsed_string_len = grn_vector_get_element(ctx,
                                               &parsed_strings,
                                               0,
                                               &parsed_string,
                                               NULL,
                                               NULL);
    size_t estimated_size =
      grn_ii_estimate_size_for_query(ctx, ii,
                                     parsed_string,
                                     parsed_string_len,
                                     optarg);
    if (i == 0) {
      size = estimated_size;
    } else {
      if (estimated_size < size) {
        size = estimated_size;
      }
    }
  }
  GRN_OBJ_FIN(ctx, &parsed_strings);

  if (optarg) {
    optarg->mode = GRN_OP_REGEXP;
  }

  return size;
}

uint32_t
grn_ii_estimate_size_for_query(grn_ctx *ctx, grn_ii *ii,
                               const char *query, unsigned int query_len,
                               grn_search_optarg *optarg)
{
  const char *tag = "[ii][estimate][size][query]";

  if (query_len == 0) {
    return 0;
  }

  grn_select_optarg select_optarg;
  grn_select_optarg_init_by_search_optarg(ctx, &select_optarg, optarg);

  grn_ii_select_data data;
  data.ii = ii;
  data.lexicon = data.ii->lexicon;
  data.query = query;
  data.query_len = query_len;
  grn_ii_select_data_init(ctx, &data, &select_optarg);
  if (data.mode == GRN_OP_REGEXP) {
    grn_ii_select_data_fin(ctx, &data);
    return grn_ii_estimate_size_for_query_regexp(ctx,
                                                 ii,
                                                 query,
                                                 query_len,
                                                 optarg);
  }

  if (!grn_ii_select_data_init_token_infos(ctx, &data, tag)) {
    grn_ii_select_data_fin(ctx, &data);
    return 0;
  }

  uint32_t i;
  double estimated_size = 0;
  double normalized_ratio = 1.0;
  for (i = 0; i < data.n_token_infos; i++) {
    token_info *ti = data.token_infos[i];
    double term_estimated_size;
    term_estimated_size = ((double)ti->size / ti->ntoken);
    if (i == 0) {
      estimated_size = term_estimated_size;
    } else {
      if (term_estimated_size < estimated_size) {
        estimated_size = term_estimated_size;
      }
      normalized_ratio *= grn_ii_estimate_size_for_query_reduce_ratio;
    }
  }

  estimated_size *= normalized_ratio;
  if (estimated_size > 0.0 && estimated_size < 1.0) {
    estimated_size = 1.0;
  }

  grn_ii_select_data_fin(ctx, &data);

  return estimated_size;
}

uint32_t
grn_ii_estimate_size_for_lexicon_cursor(grn_ctx *ctx, grn_ii *ii,
                                        grn_table_cursor *lexicon_cursor)
{
  grn_id term_id;
  uint32_t estimated_size = 0;

  while ((term_id = grn_table_cursor_next(ctx, lexicon_cursor)) != GRN_ID_NIL) {
    uint32_t term_estimated_size;
    term_estimated_size = grn_ii_estimate_size(ctx, ii, term_id);
    estimated_size += term_estimated_size;
  }

  return estimated_size;
}

grn_rc
grn_ii_sel(grn_ctx *ctx, grn_ii *ii, const char *string, unsigned int string_len,
           grn_hash *s, grn_operator op, grn_search_optarg *optarg)
{
  ERRCLR(ctx);
  if (grn_logger_pass(ctx, GRN_LOG_INFO)) {
    if (grn_type_id_is_text_family(ctx, ii->lexicon->header.domain)) {
      GRN_LOG(ctx, GRN_LOG_INFO, "grn_ii_sel > (%.*s)", string_len, string);
    } else {
      grn_obj inspected;
      GRN_TEXT_INIT(&inspected, 0);
      grn_inspect_key(ctx, &inspected, ii->lexicon, string, string_len);
      GRN_LOG(ctx, GRN_LOG_INFO,
              "grn_ii_sel > (%.*s)",
              (int)GRN_TEXT_LEN(&inspected),
              GRN_TEXT_VALUE(&inspected));
      GRN_OBJ_FIN(ctx, &inspected);
    }
  }
  if (!s) { return GRN_INVALID_ARGUMENT; }
  {
    grn_select_optarg arg;
    grn_select_optarg_init_by_search_optarg(ctx, &arg, optarg);
    /* todo : support subrec
    grn_rset_init(ctx, s, GRN_REC_DOCUMENT, 0, GRN_REC_NONE, 0, 0);
    */
    if (grn_ii_select(ctx, ii, string, string_len, s, op, &arg)) {
      GRN_LOG(ctx, GRN_LOG_ERROR, "grn_ii_select on grn_ii_sel(1) failed !");
      return ctx->rc;
    }
    GRN_LOG(ctx, GRN_LOG_INFO, "exact: %d", GRN_HASH_SIZE(s));
    if (op == GRN_OP_OR || ctx->impl->force_match_escalation) {
      grn_id min = GRN_ID_NIL;
      if ((int64_t)GRN_HASH_SIZE(s) <= ctx->impl->match_escalation_threshold ||
          ctx->impl->force_match_escalation) {
        arg.mode = GRN_OP_UNSPLIT;
        if (arg.match_info) {
          if (arg.match_info->flags & GRN_MATCH_INFO_GET_MIN_RECORD_ID) {
            min = arg.match_info->min;
            arg.match_info->min = GRN_ID_NIL;
          }
        }
        if (grn_ii_select(ctx, ii, string, string_len, s, op, &arg)) {
          GRN_LOG(ctx, GRN_LOG_ERROR,
                  "grn_ii_select on grn_ii_sel(2) failed !");
          return ctx->rc;
        }
        GRN_LOG(ctx, GRN_LOG_INFO, "unsplit: %d", GRN_HASH_SIZE(s));
        if (arg.match_info) {
          if (arg.match_info->flags & GRN_MATCH_INFO_GET_MIN_RECORD_ID) {
            if (min > GRN_ID_NIL && min < arg.match_info->min) {
              arg.match_info->min = min;
            }
          }
        }
      }
      if ((int64_t)GRN_HASH_SIZE(s) <= ctx->impl->match_escalation_threshold ||
          ctx->impl->force_match_escalation) {
        arg.mode = GRN_OP_PARTIAL;
        if (arg.match_info) {
          if (arg.match_info->flags & GRN_MATCH_INFO_GET_MIN_RECORD_ID) {
            min = arg.match_info->min;
            arg.match_info->min = GRN_ID_NIL;
          }
        }
        if (grn_ii_select(ctx, ii, string, string_len, s, op, &arg)) {
          GRN_LOG(ctx, GRN_LOG_ERROR,
                  "grn_ii_select on grn_ii_sel(3) failed !");
          return ctx->rc;
        }
        GRN_LOG(ctx, GRN_LOG_INFO, "partial: %d", GRN_HASH_SIZE(s));
        if (arg.match_info) {
          if (arg.match_info->flags & GRN_MATCH_INFO_GET_MIN_RECORD_ID) {
            if (min > GRN_ID_NIL && min < arg.match_info->min) {
              arg.match_info->min = min;
            }
          }
        }
      }
    }
    GRN_LOG(ctx, GRN_LOG_INFO, "hits=%d", GRN_HASH_SIZE(s));
    return GRN_SUCCESS;
  }
}

grn_rc
grn_ii_at(grn_ctx *ctx, grn_ii *ii, grn_id id, grn_hash *s, grn_operator op)
{
  int rep = 0;
  grn_ii_cursor *c;
  if ((c = grn_ii_cursor_open(ctx, ii, id, GRN_ID_NIL, GRN_ID_MAX,
                              rep ? ii->n_elements : ii->n_elements - 1, 0))) {
    grn_result_set_add_ii_cursor(ctx, s, c, 1, 1, op);
    grn_ii_cursor_close(ctx, c);
  }
  return ctx->rc;
}

void
grn_ii_resolve_sel_and(grn_ctx *ctx, grn_hash *s, grn_operator op)
{
  if (op == GRN_OP_AND
      && !(ctx->flags & GRN_CTX_TEMPORARY_DISABLE_II_RESOLVE_SEL_AND)) {
    grn_id eid;
    grn_rset_recinfo *ri;
    grn_hash_cursor *c = grn_hash_cursor_open(ctx, s, NULL, 0, NULL, 0,
                                              0, -1, 0);
    if (c) {
      while ((eid = grn_hash_cursor_next(ctx, c))) {
        grn_hash_cursor_get_value(ctx, c, (void **) &ri);
        if ((ri->n_subrecs & GRN_RSET_UTIL_BIT)) {
          ri->n_subrecs &= ~GRN_RSET_UTIL_BIT;
        } else {
          grn_hash_delete_by_id(ctx, s, eid, NULL);
        }
      }
      grn_hash_cursor_close(ctx, c);
    }
  }
}

void
grn_ii_cursor_inspect(grn_ctx *ctx, grn_ii_cursor *c, grn_obj *buf)
{
  grn_obj key_buf;
  char key[GRN_TABLE_MAX_KEY_SIZE];
  int key_size;
  int i = 0;
  grn_ii_cursor_next_options options = {
    .include_garbage = GRN_TRUE
  };

  GRN_TEXT_PUTS(ctx, buf, "  #<");
  key_size = grn_table_get_key(ctx, c->ii->lexicon, c->id,
                               key, GRN_TABLE_MAX_KEY_SIZE);
  GRN_OBJ_INIT(&key_buf, GRN_BULK, 0, c->ii->lexicon->header.domain);
  GRN_TEXT_SET(ctx, &key_buf, key, key_size);
  grn_inspect(ctx, buf, &key_buf);
  GRN_OBJ_FIN(ctx, &key_buf);

  GRN_TEXT_PUTS(ctx, buf, "\n    elements:[\n      ");
  while (grn_ii_cursor_next_internal(ctx, c, &options)) {
    grn_posting *pos = c->post;
    if (i > 0) {
      GRN_TEXT_PUTS(ctx, buf, ",\n      ");
    }
    i++;
    GRN_TEXT_PUTS(ctx, buf, "{status:");
    if (pos->tf && pos->sid) {
      GRN_TEXT_PUTS(ctx, buf, "available");
    } else {
      GRN_TEXT_PUTS(ctx, buf, "garbage");
    }
    GRN_TEXT_PUTS(ctx, buf, ", rid:");
    grn_text_lltoa(ctx, buf, pos->rid);
    GRN_TEXT_PUTS(ctx, buf, ", sid:");
    grn_text_lltoa(ctx, buf, pos->sid);
    GRN_TEXT_PUTS(ctx, buf, ", pos:");
    grn_text_lltoa(ctx, buf, pos->pos);
    GRN_TEXT_PUTS(ctx, buf, ", tf:");
    grn_text_lltoa(ctx, buf, pos->tf);
    GRN_TEXT_PUTS(ctx, buf, ", weight:");
    grn_text_f32toa(ctx, buf, grn_posting_get_weight_float(ctx, pos));
    GRN_TEXT_PUTS(ctx, buf, ", rest:");
    grn_text_lltoa(ctx, buf, pos->rest);
    GRN_TEXT_PUTS(ctx, buf, "}");
  }
  GRN_TEXT_PUTS(ctx, buf, "\n    ]\n  >");
}

void
grn_ii_inspect_values(grn_ctx *ctx, grn_ii *ii, grn_obj *buf)
{
  grn_table_cursor *tc;
  GRN_TEXT_PUTS(ctx, buf, "[");
  if ((tc = grn_table_cursor_open(ctx, ii->lexicon, NULL, 0, NULL, 0, 0, -1,
                                  GRN_CURSOR_ASCENDING))) {
    int i = 0;
    grn_id tid;
    grn_ii_cursor *c;
    while ((tid = grn_table_cursor_next(ctx, tc))) {
      if (i > 0) {
        GRN_TEXT_PUTS(ctx, buf, ",");
      }
      i++;
      GRN_TEXT_PUTS(ctx, buf, "\n");
      if ((c = grn_ii_cursor_open(ctx, ii, tid, GRN_ID_NIL, GRN_ID_MAX,
                                  ii->n_elements,
                                  GRN_OBJ_WITH_POSITION|GRN_OBJ_WITH_SECTION))) {
        grn_ii_cursor_inspect(ctx, c, buf);
        grn_ii_cursor_close(ctx, c);
      }
    }
    grn_table_cursor_close(ctx, tc);
  }
  GRN_TEXT_PUTS(ctx, buf, "]");
}

/********************** buffered index builder ***********************/

const grn_id II_BUFFER_TYPE_MASK = 0xc0000000;
#define II_BUFFER_TYPE_RID         0x80000000
#define II_BUFFER_TYPE_WEIGHT      0x40000000
#define II_BUFFER_TYPE(id)          (((id) & II_BUFFER_TYPE_MASK))
#define II_BUFFER_PACK(value, type) ((value) | (type))
#define II_BUFFER_UNPACK(id, type)  ((id) & ~(type))
#define II_BUFFER_ORDER             GRN_CURSOR_BY_KEY
const uint16_t II_BUFFER_NTERMS_PER_BUFFER = 16380;
const uint32_t II_BUFFER_PACKED_BUF_SIZE = 0x4000000;
const char *TMPFILE_PATH = "grn_ii_buffer_tmp";
const uint32_t II_BUFFER_NCOUNTERS_MARGIN = 0x100000;
const size_t II_BUFFER_BLOCK_SIZE = 0x1000000;
const uint32_t II_BUFFER_BLOCK_READ_UNIT_SIZE = 0x200000;

typedef struct {
  unsigned int sid;    /* Section ID */
  uint32_t weight; /* Weight */
  const char *p;       /* Value address */
  uint32_t len;        /* Value length */
  char *buf;           /* Buffer address */
  uint32_t cap;        /* Buffer size */
} ii_buffer_value;

/* ii_buffer_counter is associated with a combination of a block an a term. */
typedef struct {
  uint32_t nrecs;  /* Number of records or sections */
  uint32_t nposts; /* Number of occurrences */

  /* Information of the last value */
  grn_id last_rid;      /* Record ID */
  uint32_t last_sid;    /* Section ID */
  uint32_t last_tf;     /* Term frequency */
  uint32_t last_weight; /* Total weight */
  uint32_t last_pos;    /* Token position */

  /* Meaning of offset_* is different before/after encoding. */
  /* Before encoding: size in encoded sequence */
  /* After encoding: Offset in encoded sequence */
  uint32_t offset_rid;    /* Record ID */
  uint32_t offset_sid;    /* Section ID */
  uint32_t offset_tf;     /* Term frequency */
  uint32_t offset_weight; /* Weight */
  uint32_t offset_pos;    /* Token position */
} ii_buffer_counter;

typedef struct {
  off64_t head;
  off64_t tail;
  uint32_t nextsize;
  uint8_t *buffer;
  uint32_t buffersize;
  uint8_t *bufcur;
  uint32_t rest;
  grn_id tid;
  uint32_t nrecs;
  uint32_t nposts;
  grn_id *recs;
  uint32_t *tfs;
  uint32_t *posts;
} ii_buffer_block;

struct _grn_ii_buffer {
  grn_obj *lexicon;            /* Global lexicon */
  grn_obj *tmp_lexicon;        /* Temporary lexicon for each block */
  ii_buffer_block *blocks;     /* Blocks */
  uint32_t nblocks;            /* Number of blocks */
  int tmpfd;                   /* Descriptor of temporary file */
  char tmpfpath[PATH_MAX];     /* Path of temporary file */
  uint64_t update_buffer_size;

  // stuff for parsing
  off64_t filepos;             /* Write position of temporary file */
  grn_id *block_buf;           /* Buffer for the current block */
  size_t block_buf_size;       /* Size of block_buf */
  size_t block_pos;            /* Write position of block_buf */
  ii_buffer_counter *counters; /* Status of terms */
  uint32_t ncounters;          /* Number of counters */
  size_t total_size;
  size_t curr_size;
  ii_buffer_value *values;     /* Values in block */
  unsigned int nvalues;        /* Number of values in block */
  unsigned int max_nvalues;    /* Size of values */
  grn_id last_rid;

  // stuff for merging
  grn_ii *ii;
  uint32_t lseg;
  uint32_t dseg;
  buffer *term_buffer;
  datavec data_vectors[MAX_N_ELEMENTS + 1];
  uint8_t *packed_buf;
  size_t packed_buf_size;
  size_t packed_len;
  size_t total_chunk_size;
};

/* block_new returns a new ii_buffer_block to store block information. */
static ii_buffer_block *
block_new(grn_ctx *ctx, grn_ii_buffer *ii_buffer)
{
  ii_buffer_block *block;
  if (!(ii_buffer->nblocks & 0x3ff)) {
    ii_buffer_block *blocks;
    if (!(blocks = GRN_REALLOC(ii_buffer->blocks,
                               (ii_buffer->nblocks + 0x400) *
                               sizeof(ii_buffer_block)))) {
      return NULL;
    }
    ii_buffer->blocks = blocks;
  }
  block = &ii_buffer->blocks[ii_buffer->nblocks];
  block->head = ii_buffer->filepos;
  block->rest = 0;
  block->buffer = NULL;
  block->buffersize = 0;
  return block;
}

/* allocate_outbuf allocates memory to flush a block. */
static uint8_t *
allocate_outbuf(grn_ctx *ctx, grn_ii_buffer *ii_buffer)
{
  size_t bufsize = 0, bufsize_ = 0;
  uint32_t flags = ii_buffer->ii->header.common->flags;
  ii_buffer_counter *counter = ii_buffer->counters;
  grn_id tid, tid_max = grn_table_size(ctx, ii_buffer->tmp_lexicon);
  for (tid = 1; tid <= tid_max; counter++, tid++) {
    counter->offset_tf += GRN_B_ENC_SIZE(counter->last_tf - 1);
    counter->last_rid = 0;
    counter->last_tf = 0;
    bufsize += 5;
    bufsize += GRN_B_ENC_SIZE(counter->nrecs);
    bufsize += GRN_B_ENC_SIZE(counter->nposts);
    bufsize += counter->offset_rid;
    if ((flags & GRN_OBJ_WITH_SECTION)) {
      bufsize += counter->offset_sid;
    }
    bufsize += counter->offset_tf;
    if ((flags & GRN_OBJ_WITH_WEIGHT)) {
      bufsize += counter->offset_weight;
    }
    if ((flags & GRN_OBJ_WITH_POSITION)) {
      bufsize += counter->offset_pos;
    }
    if (bufsize_ + II_BUFFER_BLOCK_READ_UNIT_SIZE < bufsize) {
      bufsize += sizeof(uint32_t);
      bufsize_ = bufsize;
    }
  }
  GRN_LOG(ctx, GRN_LOG_INFO, "flushing:%d bufsize:%" GRN_FMT_SIZE,
          ii_buffer->nblocks, bufsize);
  return (uint8_t *)GRN_MALLOC(bufsize);
}

/*
 * The temporary file format is roughly as follows:
 *
 * File  = Block...
 * Block = Unit...
 * Unit  = TermChunk (key order)
 *         NextUnitSize (The first unit size is kept on memory)
 * Chunk = Term...
 * Term  = ID (gtid)
 *         NumRecordsOrSections (nrecs), NumOccurrences (nposts)
 *         RecordID... (rid, diff)
 *         [SectionID... (sid, diff)]
 *         TermFrequency... (tf, diff)
 *         [Weight... (weight, diff)]
 *         [Position... (pos, diff)]
 */

/*
 * encode_terms encodes terms in ii_buffer->tmp_lexicon and returns the
 * expected temporary file size.
 */
static size_t
encode_terms(grn_ctx *ctx, grn_ii_buffer *ii_buffer,
             uint8_t *outbuf, ii_buffer_block *block)
{
  grn_id tid;
  uint8_t *outbufp = outbuf;
  uint8_t *outbufp_ = outbuf;
  grn_table_cursor  *tc;
  /* The first size is written into block->nextsize. */
  uint8_t *pnext = (uint8_t *)&block->nextsize;
  uint32_t flags = ii_buffer->ii->header.common->flags;
  tc = grn_table_cursor_open(ctx, ii_buffer->tmp_lexicon,
                             NULL, 0, NULL, 0, 0, -1, II_BUFFER_ORDER);
  while ((tid = grn_table_cursor_next(ctx, tc)) != GRN_ID_NIL) {
    char key[GRN_TABLE_MAX_KEY_SIZE];
    int key_size = grn_table_get_key(ctx, ii_buffer->tmp_lexicon, tid,
                                     key, GRN_TABLE_MAX_KEY_SIZE);
    /* gtid is a global term ID, not in a temporary lexicon. */
    grn_id gtid = grn_table_add(ctx, ii_buffer->lexicon, key, key_size, NULL);
    ii_buffer_counter *counter = &ii_buffer->counters[tid - 1];
    if (counter->nrecs) {
      uint32_t offset_rid = counter->offset_rid;
      uint32_t offset_sid = counter->offset_sid;
      uint32_t offset_tf = counter->offset_tf;
      uint32_t offset_weight = counter->offset_weight;
      uint32_t offset_pos = counter->offset_pos;
      GRN_B_ENC(gtid, outbufp);
      GRN_B_ENC(counter->nrecs, outbufp);
      GRN_B_ENC(counter->nposts, outbufp);
      ii_buffer->total_size += counter->nrecs + counter->nposts;
      counter->offset_rid = outbufp - outbuf;
      outbufp += offset_rid;
      if ((flags & GRN_OBJ_WITH_SECTION)) {
        counter->offset_sid = outbufp - outbuf;
        outbufp += offset_sid;
      }
      counter->offset_tf = outbufp - outbuf;
      outbufp += offset_tf;
      if ((flags & GRN_OBJ_WITH_WEIGHT)) {
        counter->offset_weight = outbufp - outbuf;
        outbufp += offset_weight;
      }
      if ((flags & GRN_OBJ_WITH_POSITION)) {
        counter->offset_pos = outbufp - outbuf;
        outbufp += offset_pos;
      }
    }
    if (outbufp_ + II_BUFFER_BLOCK_READ_UNIT_SIZE < outbufp) {
      uint32_t size = outbufp - outbufp_ + sizeof(uint32_t);
      grn_memcpy(pnext, &size, sizeof(uint32_t));
      pnext = outbufp;
      outbufp += sizeof(uint32_t);
      outbufp_ = outbufp;
    }
  }
  grn_table_cursor_close(ctx, tc);
  if (outbufp_ < outbufp) {
    uint32_t size = outbufp - outbufp_;
    grn_memcpy(pnext, &size, sizeof(uint32_t));
  }
  return outbufp - outbuf;
}

/* encode_postings encodes data in ii_buffer->block_buf. */
static void
encode_postings(grn_ctx *ctx, grn_ii_buffer *ii_buffer, uint8_t *outbuf)
{
  grn_id rid = 0;
  unsigned int sid = 1;
  uint32_t weight = 0;
  uint32_t pos = 0;
  uint32_t rest;
  grn_id *bp = ii_buffer->block_buf;
  uint32_t flags = ii_buffer->ii->header.common->flags;
  for (rest = ii_buffer->block_pos; rest; bp++, rest--) {
    grn_id id = *bp;
    switch (II_BUFFER_TYPE(id)) {
    case II_BUFFER_TYPE_RID :
      rid = II_BUFFER_UNPACK(id, II_BUFFER_TYPE_RID);
      if ((flags & GRN_OBJ_WITH_SECTION) && rest) {
        sid = *++bp;
        rest--;
      }
      weight = 0;
      pos = 0;
      break;
    case II_BUFFER_TYPE_WEIGHT :
      weight = II_BUFFER_UNPACK(id, II_BUFFER_TYPE_WEIGHT);
      break;
    default :
      {
        ii_buffer_counter *counter = &ii_buffer->counters[id - 1];
        if (counter->last_rid == rid && counter->last_sid == sid) {
          counter->last_tf++;
          counter->last_weight += weight;
        } else {
          if (counter->last_tf) {
            uint8_t *p = outbuf + counter->offset_tf;
            GRN_B_ENC(counter->last_tf - 1, p);
            counter->offset_tf = p - outbuf;
            if (flags & GRN_OBJ_WITH_WEIGHT) {
              p = outbuf + counter->offset_weight;
              GRN_B_ENC(counter->last_weight, p);
              counter->offset_weight = p - outbuf;
            }
          }
          {
            uint8_t *p = outbuf + counter->offset_rid;
            GRN_B_ENC(rid - counter->last_rid, p);
            counter->offset_rid = p - outbuf;
          }
          if (flags & GRN_OBJ_WITH_SECTION) {
            uint8_t *p = outbuf + counter->offset_sid;
            if (counter->last_rid != rid) {
              GRN_B_ENC(sid - 1, p);
            } else {
              GRN_B_ENC(sid - counter->last_sid - 1, p);
            }
            counter->offset_sid = p - outbuf;
          }
          counter->last_rid = rid;
          counter->last_sid = sid;
          counter->last_tf = 1;
          counter->last_weight = weight;
          counter->last_pos = 0;
        }
        if ((flags & GRN_OBJ_WITH_POSITION) && rest) {
          uint8_t *p = outbuf + counter->offset_pos;
          pos = *++bp;
          rest--;
          GRN_B_ENC(pos - counter->last_pos, p);
          counter->offset_pos = p - outbuf;
          counter->last_pos = pos;
        }
      }
      break;
    }
  }
}

/* encode_last_tf encodes last_tf and last_weight in counters. */
static void
encode_last_tf(grn_ctx *ctx, grn_ii_buffer *ii_buffer, uint8_t *outbuf)
{
  ii_buffer_counter *counter = ii_buffer->counters;
  grn_id tid, tid_max = grn_table_size(ctx, ii_buffer->tmp_lexicon);
  for (tid = 1; tid <= tid_max; counter++, tid++) {
    uint8_t *p = outbuf + counter->offset_tf;
    GRN_B_ENC(counter->last_tf - 1, p);
  }
  if ((ii_buffer->ii->header.common->flags & GRN_OBJ_WITH_WEIGHT)) {
    for (tid = 1; tid <= tid_max; counter++, tid++) {
      uint8_t *p = outbuf + counter->offset_weight;
      GRN_B_ENC(counter->last_weight, p);
    }
  }
}

/*
 * grn_ii_buffer_flush flushes the current block (ii_buffer->block_buf,
 * counters and tmp_lexicon) to a temporary file (ii_buffer->tmpfd).
 * Also, block information is stored into ii_buffer->blocks.
 */
static void
grn_ii_buffer_flush(grn_ctx *ctx, grn_ii_buffer *ii_buffer)
{
  size_t encsize;
  uint8_t *outbuf;
  ii_buffer_block *block;
  GRN_LOG(ctx, GRN_LOG_DEBUG, "flushing:%d npostings:%" GRN_FMT_SIZE,
          ii_buffer->nblocks, ii_buffer->block_pos);
  if (!(block = block_new(ctx, ii_buffer))) { return; }
  if (!(outbuf = allocate_outbuf(ctx, ii_buffer))) { return; }
  encsize = encode_terms(ctx, ii_buffer, outbuf, block);
  encode_postings(ctx, ii_buffer, outbuf);
  encode_last_tf(ctx, ii_buffer, outbuf);
  {
    ssize_t r = grn_write(ii_buffer->tmpfd, outbuf, encsize);
    if (r == -1 || (size_t)r != encsize) {
      ERR(GRN_INPUT_OUTPUT_ERROR,
          "write returned %" GRN_FMT_INT64D " != %" GRN_FMT_INT64U,
          (int64_t)r, (uint64_t)encsize);
      GRN_FREE(outbuf);
      return;
    }
    ii_buffer->filepos += r;
    block->tail = ii_buffer->filepos;
  }
  GRN_FREE(outbuf);
  memset(ii_buffer->counters, 0,
         grn_table_size(ctx, ii_buffer->tmp_lexicon) *
         sizeof(ii_buffer_counter));
  grn_obj_close(ctx, ii_buffer->tmp_lexicon);
  GRN_LOG(ctx, GRN_LOG_DEBUG, "flushed: %d encsize:%" GRN_FMT_SIZE,
          ii_buffer->nblocks, encsize);
  ii_buffer->tmp_lexicon = NULL;
  ii_buffer->nblocks++;
  ii_buffer->block_pos = 0;
}

/*
 * get_tmp_lexicon returns a temporary lexicon.
 *
 * Note that a lexicon is created for each block and ii_buffer->tmp_lexicon is
 * closed in grn_ii_buffer_flush.
 */
static grn_obj *
get_tmp_lexicon(grn_ctx *ctx, grn_ii_buffer *ii_buffer)
{
  grn_obj *tmp_lexicon = ii_buffer->tmp_lexicon;
  if (!tmp_lexicon) {
    grn_obj *domain = grn_ctx_at(ctx, ii_buffer->lexicon->header.domain);
    grn_obj *range = grn_ctx_at(ctx, DB_OBJ(ii_buffer->lexicon)->range);
    grn_table_flags flags;
    grn_table_get_info(ctx, ii_buffer->lexicon, &flags, NULL,
                       NULL, NULL, NULL);
    flags &= ~GRN_OBJ_PERSISTENT;
    tmp_lexicon = grn_table_create(ctx, NULL, 0, NULL, flags, domain, range);
    if (tmp_lexicon) {
      ii_buffer->tmp_lexicon = tmp_lexicon;
      {
        grn_obj tokenizer;
        GRN_TEXT_INIT(&tokenizer, 0);
        grn_table_get_default_tokenizer_string(ctx,
                                               ii_buffer->lexicon,
                                               &tokenizer);
        if (GRN_TEXT_LEN(&tokenizer) > 0) {
          grn_obj_set_info(ctx, tmp_lexicon,
                           GRN_INFO_DEFAULT_TOKENIZER, &tokenizer);
        }
        GRN_OBJ_FIN(ctx, &tokenizer);
      }
      {
        grn_obj normalizers;
        GRN_TEXT_INIT(&normalizers, 0);
        grn_table_get_normalizers_string(ctx,
                                         ii_buffer->lexicon,
                                         &normalizers);
        if (GRN_TEXT_LEN(&normalizers) > 0) {
          grn_obj_set_info(ctx, tmp_lexicon, GRN_INFO_NORMALIZERS, &normalizers);
        }
        GRN_OBJ_FIN(ctx, &normalizers);
      }
      {
        grn_obj token_filters;
        GRN_TEXT_INIT(&token_filters, 0);
        grn_table_get_token_filters_string(ctx,
                                           ii_buffer->lexicon,
                                           &token_filters);
        if (GRN_TEXT_LEN(&token_filters) > 0) {
          grn_obj_set_info(ctx,
                           tmp_lexicon,
                           GRN_INFO_TOKEN_FILTERS,
                           &token_filters);
        }
        GRN_OBJ_FIN(ctx, &token_filters);
      }
    }
  }
  return tmp_lexicon;
}

/* get_buffer_counter returns a counter associated with tid. */
static ii_buffer_counter *
get_buffer_counter(grn_ctx *ctx, grn_ii_buffer *ii_buffer,
                   grn_obj *tmp_lexicon, grn_id tid)
{
  if (tid > ii_buffer->ncounters) {
    ii_buffer_counter *counters;
    uint32_t ncounters =
      grn_table_size(ctx, tmp_lexicon) + II_BUFFER_NCOUNTERS_MARGIN;
    counters = GRN_REALLOC(ii_buffer->counters,
                           ncounters * sizeof(ii_buffer_counter));
    if (!counters) { return NULL; }
    memset(&counters[ii_buffer->ncounters], 0,
           (ncounters - ii_buffer->ncounters) * sizeof(ii_buffer_counter));
    ii_buffer->ncounters = ncounters;
    ii_buffer->counters = counters;
  }
  return &ii_buffer->counters[tid - 1];
}

/*
 * grn_ii_buffer_tokenize_value tokenizes a value.
 *
 * The result is written into the current block (ii_buffer->tmp_lexicon,
 * ii_buffer->block_buf, ii_buffer->counters, etc.).
 */
static void
grn_ii_buffer_tokenize_value(grn_ctx *ctx, grn_ii_buffer *ii_buffer,
                             grn_id rid, const ii_buffer_value *value)
{
  grn_obj *tmp_lexicon;
  if ((tmp_lexicon = get_tmp_lexicon(ctx, ii_buffer))) {
    unsigned int token_flags = 0;
    grn_token_cursor *token_cursor;
    grn_id *buffer = ii_buffer->block_buf;
    uint32_t block_pos = ii_buffer->block_pos;
    uint32_t ii_flags = ii_buffer->ii->header.common->flags;
    buffer[block_pos++] = II_BUFFER_PACK(rid, II_BUFFER_TYPE_RID);
    if (ii_flags & GRN_OBJ_WITH_SECTION) {
      buffer[block_pos++] = value->sid;
    }
    if (value->weight) {
      buffer[block_pos++] = II_BUFFER_PACK(value->weight,
                                           II_BUFFER_TYPE_WEIGHT);
    }
    if ((token_cursor = grn_token_cursor_open(ctx, tmp_lexicon,
                                              value->p, value->len,
                                              GRN_TOKEN_ADD, token_flags))) {
      while (!token_cursor->status) {
        grn_id tid;
        if ((tid = grn_token_cursor_next(ctx, token_cursor))) {
          ii_buffer_counter *counter;
          counter = get_buffer_counter(ctx, ii_buffer, tmp_lexicon, tid);
          if (!counter) { return; }
          buffer[block_pos++] = tid;
          if (ii_flags & GRN_OBJ_WITH_POSITION) {
            buffer[block_pos++] = token_cursor->pos;
          }
          if (counter->last_rid != rid) {
            counter->offset_rid += GRN_B_ENC_SIZE(rid - counter->last_rid);
            counter->last_rid = rid;
            counter->offset_sid += GRN_B_ENC_SIZE(value->sid - 1);
            counter->last_sid = value->sid;
            if (counter->last_tf) {
              counter->offset_tf += GRN_B_ENC_SIZE(counter->last_tf - 1);
              counter->last_tf = 0;
              counter->offset_weight += GRN_B_ENC_SIZE(counter->last_weight);
              counter->last_weight = 0;
            }
            counter->last_pos = 0;
            counter->nrecs++;
          } else if (counter->last_sid != value->sid) {
            counter->offset_rid += GRN_B_ENC_SIZE(0);
            counter->offset_sid +=
              GRN_B_ENC_SIZE(value->sid - counter->last_sid - 1);
            counter->last_sid = value->sid;
            if (counter->last_tf) {
              counter->offset_tf += GRN_B_ENC_SIZE(counter->last_tf - 1);
              counter->last_tf = 0;
              counter->offset_weight += GRN_B_ENC_SIZE(counter->last_weight);
              counter->last_weight = 0;
            }
            counter->last_pos = 0;
            counter->nrecs++;
          }
          counter->offset_pos +=
            GRN_B_ENC_SIZE(token_cursor->pos - counter->last_pos);
          counter->last_pos = token_cursor->pos;
          counter->last_tf++;
          counter->last_weight += value->weight;
          counter->nposts++;
        }
      }
      grn_token_cursor_close(ctx, token_cursor);
    }
    ii_buffer->block_pos = block_pos;
  }
}

/*
 * grn_ii_buffer_tokenize tokenizes ii_buffer->values.
 *
 * grn_ii_buffer_tokenize estimates the size of tokenized values.
 * If the remaining space of the current block is not enough to store the new
 * tokenized values, the current block is flushed.
 * Then, grn_ii_buffer_tokenize tokenizes values.
 */
static void
grn_ii_buffer_tokenize(grn_ctx *ctx, grn_ii_buffer *ii_buffer, grn_id rid)
{
  unsigned int i;
  uint32_t est_len = 0;
  for (i = 0; i < ii_buffer->nvalues; i++) {
    est_len += ii_buffer->values[i].len * 2 + 2;
  }
  if (ii_buffer->block_buf_size < ii_buffer->block_pos + est_len) {
    grn_ii_buffer_flush(ctx, ii_buffer);
  }
  if (ii_buffer->block_buf_size < est_len) {
    grn_id *block_buf = (grn_id *)GRN_REALLOC(ii_buffer->block_buf,
                                              est_len * sizeof(grn_id));
    if (block_buf) {
      ii_buffer->block_buf = block_buf;
      ii_buffer->block_buf_size = est_len;
    }
  }

  for (i = 0; i < ii_buffer->nvalues; i++) {
    const ii_buffer_value *value = &ii_buffer->values[i];
    if (value->len) {
      uint32_t est_len = value->len * 2 + 2;
      if (ii_buffer->block_buf_size >= ii_buffer->block_pos + est_len) {
        grn_ii_buffer_tokenize_value(ctx, ii_buffer, rid, value);
      }
    }
  }
  ii_buffer->nvalues = 0;
}

/* grn_ii_buffer_fetch fetches the next term. */
static void
grn_ii_buffer_fetch(grn_ctx *ctx, grn_ii_buffer *ii_buffer,
                    ii_buffer_block *block)
{
  if (!block->rest) {
    /* Read the next unit. */
    if (block->head < block->tail) {
      size_t bytesize = block->nextsize;
      if (block->buffersize < block->nextsize) {
        void *r = GRN_REALLOC(block->buffer, bytesize);
        if (r) {
          block->buffer = (uint8_t *)r;
          block->buffersize = block->nextsize;
        } else {
          GRN_LOG(ctx, GRN_LOG_WARNING, "realloc: %" GRN_FMT_LLU,
                  (unsigned long long int)bytesize);
          return;
        }
      }
      {
        off64_t seeked_position;
        seeked_position = grn_lseek(ii_buffer->tmpfd, block->head, SEEK_SET);
        if (seeked_position != block->head) {
          ERRNO_ERR("failed to "
                    "grn_lseek(%" GRN_FMT_OFF64_T ") -> %" GRN_FMT_OFF64_T,
                    block->head,
                    seeked_position);
          return;
        }
      }
      {
        size_t read_bytesize;
        read_bytesize = grn_read(ii_buffer->tmpfd, block->buffer, bytesize);
        if (read_bytesize != bytesize) {
          SERR("failed to grn_read(%" GRN_FMT_SIZE ") -> %" GRN_FMT_SIZE,
               bytesize, read_bytesize);
          return;
        }
      }
      block->head += bytesize;
      block->bufcur = block->buffer;
      if (block->head >= block->tail) {
        if (block->head > block->tail) {
          GRN_LOG(ctx, GRN_LOG_WARNING,
                  "fetch error: %" GRN_FMT_INT64D " > %" GRN_FMT_INT64D,
                  block->head, block->tail);
        }
        block->rest = block->nextsize;
        block->nextsize = 0;
      } else {
        block->rest = block->nextsize - sizeof(uint32_t);
        grn_memcpy(&block->nextsize,
                   &block->buffer[block->rest], sizeof(uint32_t));
      }
    }
  }
  if (block->rest) {
    uint8_t *p = block->bufcur;
    GRN_B_DEC(block->tid, p);
    GRN_B_DEC(block->nrecs, p);
    GRN_B_DEC(block->nposts, p);
    block->rest -= (p - block->bufcur);
    block->bufcur = p;
  } else {
    block->tid = 0;
  }
}

/* grn_ii_buffer_chunk_flush flushes the current buffer for packed postings. */
static void
grn_ii_buffer_chunk_flush(grn_ctx *ctx, grn_ii_buffer *ii_buffer)
{
  grn_io_win io_win;
  uint32_t chunk_number;
  chunk_new(ctx, ii_buffer->ii, &chunk_number, ii_buffer->packed_len);
  GRN_LOG(ctx, GRN_LOG_INFO, "chunk:%d, packed_len:%" GRN_FMT_SIZE,
          chunk_number, ii_buffer->packed_len);
  fake_map(ctx, ii_buffer->ii->chunk, &io_win, ii_buffer->packed_buf,
           chunk_number, ii_buffer->packed_len);
  grn_io_win_unmap(ctx, &io_win);
  ii_buffer->term_buffer->header.chunk = chunk_number;
  ii_buffer->term_buffer->header.chunk_size = ii_buffer->packed_len;
  ii_buffer->term_buffer->header.buffer_free =
    S_SEGMENT - sizeof(buffer_header) -
    ii_buffer->term_buffer->header.nterms * sizeof(buffer_term);
  ii_buffer->term_buffer->header.nterms_void = 0;
  buffer_segment_update(ii_buffer->ii, ii_buffer->lseg, ii_buffer->dseg);
  ii_buffer->ii->header.common->total_chunk_size += ii_buffer->packed_len;
  ii_buffer->total_chunk_size += ii_buffer->packed_len;
  GRN_LOG(ctx, GRN_LOG_DEBUG,
          "nterms=%d chunk=%d total=%" GRN_FMT_INT64U "KB",
          ii_buffer->term_buffer->header.nterms,
          ii_buffer->term_buffer->header.chunk_size,
          ii_buffer->ii->header.common->total_chunk_size >> 10);
  ii_buffer->term_buffer = NULL;
  ii_buffer->packed_buf = NULL;
  ii_buffer->packed_len = 0;
  ii_buffer->packed_buf_size = 0;
  ii_buffer->curr_size = 0;
}

/*
 * merge_hit_blocks merges hit blocks into ii_buffer->data_vectors.
 * merge_hit_blocks returns the estimated maximum size in bytes.
 */
static size_t
merge_hit_blocks(grn_ctx *ctx, grn_ii_buffer *ii_buffer,
                 ii_buffer_block *hits[], int nhits)
{
  uint64_t nrecs = 0;
  uint64_t nposts = 0;
  size_t max_size;
  uint64_t flags = ii_buffer->ii->header.common->flags;
  int i;
  for (i = 0; i < nhits; i++) {
    ii_buffer_block *block = hits[i];
    nrecs += block->nrecs;
    nposts += block->nposts;
  }
  ii_buffer->curr_size += nrecs + nposts;
  max_size = nrecs * (ii_buffer->ii->n_elements);
  if (flags & GRN_OBJ_WITH_POSITION) { max_size += nposts - nrecs; }
  datavec_reset(ctx, ii_buffer->data_vectors,
                ii_buffer->ii->n_elements, nrecs, max_size);
  {
    int i;
    uint32_t lr = 0; /* Last rid */
    uint64_t spos = 0;
    uint32_t *ridp, *sidp = NULL, *tfp, *weightp = NULL, *posp = NULL;
    {
      /* Get write positions in datavec. */
      int j = 0;
      ridp = ii_buffer->data_vectors[j++].data;
      if (flags & GRN_OBJ_WITH_SECTION) {
        sidp = ii_buffer->data_vectors[j++].data;
      }
      tfp = ii_buffer->data_vectors[j++].data;
      if (flags & GRN_OBJ_WITH_WEIGHT) {
        weightp = ii_buffer->data_vectors[j++].data;
      }
      if (flags & GRN_OBJ_WITH_POSITION) {
        posp = ii_buffer->data_vectors[j++].data;
      }
    }
    for (i = 0; i < nhits; i++) {
      /* Read postings from hit blocks and join the postings into datavec. */
      ii_buffer_block *block = hits[i];
      uint8_t *p = block->bufcur;
      uint32_t n = block->nrecs;
      if (n) {
        GRN_B_DEC(*ridp, p);
        *ridp -= lr;
        lr += *ridp++;
        while (--n) {
          GRN_B_DEC(*ridp, p);
          lr += *ridp++;
        }
      }
      if ((flags & GRN_OBJ_WITH_SECTION)) {
        for (n = block->nrecs; n; n--) {
          GRN_B_DEC(*sidp++, p);
        }
      }
      for (n = block->nrecs; n; n--) {
        GRN_B_DEC(*tfp++, p);
      }
      if ((flags & GRN_OBJ_WITH_WEIGHT)) {
        for (n = block->nrecs; n; n--) {
          GRN_B_DEC(*weightp++, p);
        }
      }
      if ((flags & GRN_OBJ_WITH_POSITION)) {
        for (n = block->nposts; n; n--) {
          GRN_B_DEC(*posp, p);
          spos += *posp++;
        }
      }
      block->rest -= (p - block->bufcur);
      block->bufcur = p;
      grn_ii_buffer_fetch(ctx, ii_buffer, block);
    }
    {
      /* Set size and flags of datavec. */
      int j = 0;
      uint32_t f_s = (nrecs < 3) ? 0 : USE_P_ENC;
      uint32_t f_d = ((nrecs < 16) || (nrecs <= (lr >> 8))) ? 0 : USE_P_ENC;
      ii_buffer->data_vectors[j].data_size = nrecs;
      ii_buffer->data_vectors[j++].flags = f_d;
      if ((flags & GRN_OBJ_WITH_SECTION)) {
        ii_buffer->data_vectors[j].data_size = nrecs;
        ii_buffer->data_vectors[j++].flags = f_s;
      }
      ii_buffer->data_vectors[j].data_size = nrecs;
      ii_buffer->data_vectors[j++].flags = f_s;
      if ((flags & GRN_OBJ_WITH_WEIGHT)) {
        ii_buffer->data_vectors[j].data_size = nrecs;
        ii_buffer->data_vectors[j++].flags = f_s;
      }
      if ((flags & GRN_OBJ_WITH_POSITION)) {
        uint32_t f_p = (((nposts < 32) ||
                         (nposts <= (spos >> 13))) ? 0 : USE_P_ENC);
        ii_buffer->data_vectors[j].data_size = nposts;
        ii_buffer->data_vectors[j++].flags = f_p|ODD;
      }
    }
  }
  return (max_size + ii_buffer->ii->n_elements) * 4;
}

static buffer *
get_term_buffer(grn_ctx *ctx, grn_ii_buffer *ii_buffer)
{
  if (!ii_buffer->term_buffer) {
    const uint32_t n_logical_segments =
      grn_ii_n_logical_segments_inline(ii_buffer->ii);
    uint32_t lseg;
    for (lseg = 0; lseg < n_logical_segments; lseg++) {
      const uint32_t pseg = grn_ii_get_buffer_pseg_inline(ii_buffer->ii, lseg);
      if (pseg == GRN_II_PSEG_NOT_ASSIGNED) { break; }
    }
    if (lseg == n_logical_segments) {
      GRN_DEFINE_NAME(ii_buffer->ii);
      MERR("[ii][buffer][term-buffer] couldn't find a free buffer: "
           "<%.*s>",
           name_size, name);
      return NULL;
    }
    ii_buffer->lseg = lseg;
    ii_buffer->dseg = segment_get(ctx, ii_buffer->ii);
    void *term_buffer;
    term_buffer = grn_io_seg_ref(ctx, ii_buffer->ii->seg, ii_buffer->dseg);
    ii_buffer->term_buffer = (buffer *)term_buffer;
  }
  return ii_buffer->term_buffer;
}

/*
 * try_in_place_packing tries to pack a posting in an array element.
 *
 * The requirements are as follows:
 *  - nposts == 1
 *   - nhits == 1 && nrecs == 1 && tf == 0
 *  - weight == 0
 *  - !(flags & GRN_OBJ_WITH_SECTION) || (rid < 0x100000 && sid < 0x800)
 */
static grn_bool
try_in_place_packing(grn_ctx *ctx, grn_ii_buffer *ii_buffer,
                     grn_id tid, ii_buffer_block *hits[], int nhits)
{
  if (nhits == 1 && hits[0]->nrecs == 1 && hits[0]->nposts == 1) {
    grn_id rid;
    uint32_t sid = 1, tf, pos = 0, weight = 0;
    ii_buffer_block *block = hits[0];
    uint8_t *p = block->bufcur;
    uint32_t flags = ii_buffer->ii->header.common->flags;
    GRN_B_DEC(rid, p);
    if (flags & GRN_OBJ_WITH_SECTION) {
      GRN_B_DEC(sid, p);
      sid++;
    }
    GRN_B_DEC(tf, p);
    if (tf != 0) { GRN_LOG(ctx, GRN_LOG_WARNING, "tf=%d", tf); }
    if (flags & GRN_OBJ_WITH_WEIGHT) { GRN_B_DEC(weight, p); }
    if (flags & GRN_OBJ_WITH_POSITION) { GRN_B_DEC(pos, p); }
    if (!weight) {
      if (flags & GRN_OBJ_WITH_SECTION) {
        if (rid < 0x100000 && sid < 0x800) {
          uint32_t *a = array_get(ctx, ii_buffer->ii, tid);
          a[0] = (rid << 12) + (sid << 1) + 1;
          a[1] = pos;
          array_unref(ctx, ii_buffer->ii, tid);
        } else {
          return GRN_FALSE;
        }
      } else {
        uint32_t *a = array_get(ctx, ii_buffer->ii, tid);
        a[0] = (rid << 1) + 1;
        a[1] = pos;
        array_unref(ctx, ii_buffer->ii, tid);
      }
      block->rest -= (p - block->bufcur);
      block->bufcur = p;
      grn_ii_buffer_fetch(ctx, ii_buffer, block);
      return GRN_TRUE;
    }
  }
  return GRN_FALSE;
}

/* grn_ii_buffer_merge merges hit blocks and pack it. */
static void
grn_ii_buffer_merge(grn_ctx *ctx, grn_ii_buffer *ii_buffer,
                    grn_id tid, ii_buffer_block *hits[], int nhits)
{
  if (!try_in_place_packing(ctx, ii_buffer, tid, hits, nhits)) {
    /* Merge hit blocks and reserve a buffer for packed data. */
    size_t max_size = merge_hit_blocks(ctx, ii_buffer, hits, nhits);
    if (ii_buffer->packed_buf &&
        ii_buffer->packed_buf_size < ii_buffer->packed_len + max_size) {
      grn_ii_buffer_chunk_flush(ctx, ii_buffer);
    }
    if (!ii_buffer->packed_buf) {
      size_t buf_size = (max_size > II_BUFFER_PACKED_BUF_SIZE)
        ? max_size : II_BUFFER_PACKED_BUF_SIZE;
      if ((ii_buffer->packed_buf = GRN_MALLOC(buf_size))) {
        ii_buffer->packed_buf_size = buf_size;
      }
    }
    {
      /* Pack postings into the current buffer. */
      uint16_t nterm;
      ssize_t packed_len;
      buffer_term *bt;
      uint32_t *a;
      buffer *term_buffer;

      a = array_get(ctx, ii_buffer->ii, tid);
      if (!a) {
        grn_obj token;
        GRN_DEFINE_NAME(ii_buffer->ii);
        GRN_TEXT_INIT(&token, 0);
        grn_ii_get_term(ctx, ii_buffer->ii, tid, &token);
        MERR("[ii][buffer][merge] failed to allocate an array: "
             "<%.*s>: "
             "<%.*s>(%u)",
             name_size, name,
             (int)GRN_TEXT_LEN(&token), GRN_TEXT_VALUE(&token),
             tid);
        GRN_OBJ_FIN(ctx, &token);
        return;
      }
      term_buffer = get_term_buffer(ctx, ii_buffer);
      if (!term_buffer) {
        grn_obj token;
        GRN_DEFINE_NAME(ii_buffer->ii);
        GRN_TEXT_INIT(&token, 0);
        grn_ii_get_term(ctx, ii_buffer->ii, tid, &token);
        MERR("[ii][buffer][merge] failed to allocate a term buffer: "
             "<%.*s>: "
             "<%.*s>(%u)",
             name_size, name,
             (int)GRN_TEXT_LEN(&token), GRN_TEXT_VALUE(&token),
             tid);
        GRN_OBJ_FIN(ctx, &token);
        return;
      }
      nterm = term_buffer->header.nterms++;
      bt = &term_buffer->terms[nterm];
      a[0] = grn_ii_pos_pack(ii_buffer->ii,
                             ii_buffer->lseg,
                             POS_LOFFSET_HEADER + POS_LOFFSET_TERM * nterm);
      packed_len = grn_p_encv(ctx, ii_buffer->data_vectors,
                              ii_buffer->ii->n_elements,
                              ii_buffer->packed_buf +
                              ii_buffer->packed_len);
      a[1] = ii_buffer->data_vectors[0].data_size;
      bt->tid = tid;
      bt->size_in_buffer = 0;
      bt->pos_in_buffer = 0;
      bt->size_in_chunk = packed_len;
      bt->pos_in_chunk = ii_buffer->packed_len;
      ii_buffer->packed_len += packed_len;
      if (((ii_buffer->curr_size * ii_buffer->update_buffer_size) +
           (ii_buffer->total_size * term_buffer->header.nterms * 16)) >=
          (ii_buffer->total_size * II_BUFFER_NTERMS_PER_BUFFER * 16)) {
        grn_ii_buffer_chunk_flush(ctx, ii_buffer);
      }
      array_unref(ctx, ii_buffer->ii, tid);
    }
  }
}

grn_ii_buffer *
grn_ii_buffer_open(grn_ctx *ctx, grn_ii *ii,
                   long long unsigned int update_buffer_size)
{
  if (ii && ii->lexicon) {
    grn_ii_buffer *ii_buffer = GRN_CALLOC(sizeof(grn_ii_buffer));
    if (ii_buffer) {
      ii_buffer->ii = ii;
      ii_buffer->lexicon = ii->lexicon;
      ii_buffer->tmp_lexicon = NULL;
      ii_buffer->nblocks = 0;
      ii_buffer->blocks = NULL;
      ii_buffer->ncounters = II_BUFFER_NCOUNTERS_MARGIN;
      ii_buffer->block_pos = 0;
      ii_buffer->filepos = 0;
      ii_buffer->curr_size = 0;
      ii_buffer->total_size = 0;
      ii_buffer->update_buffer_size = update_buffer_size;
      ii_buffer->counters = GRN_CALLOC(ii_buffer->ncounters *
                                       sizeof(ii_buffer_counter));
      ii_buffer->term_buffer = NULL;
      ii_buffer->packed_buf = NULL;
      ii_buffer->packed_len = 0;
      ii_buffer->packed_buf_size = 0;
      ii_buffer->total_chunk_size = 0;
      ii_buffer->values = NULL;
      ii_buffer->nvalues = 0;
      ii_buffer->max_nvalues = 0;
      ii_buffer->last_rid = 0;
      if (ii_buffer->counters) {
        ii_buffer->block_buf = GRN_MALLOCN(grn_id, II_BUFFER_BLOCK_SIZE);
        if (ii_buffer->block_buf) {
          grn_snprintf(ii_buffer->tmpfpath, PATH_MAX, PATH_MAX,
                       "%sXXXXXX", grn_io_path(ii->seg));
          ii_buffer->block_buf_size = II_BUFFER_BLOCK_SIZE;
          ii_buffer->tmpfd = grn_mkstemp(ii_buffer->tmpfpath);
          if (ii_buffer->tmpfd != -1) {
            grn_table_flags flags;
            grn_table_get_info(ctx, ii->lexicon, &flags, NULL, NULL, NULL,
                               NULL);
            return ii_buffer;
          } else {
            SERR("failed grn_mkstemp(%s)",
                 ii_buffer->tmpfpath);
          }
          GRN_FREE(ii_buffer->block_buf);
        }
        GRN_FREE(ii_buffer->counters);
      }
      GRN_FREE(ii_buffer);
    }
  } else {
    ERR(GRN_INVALID_ARGUMENT, "ii or ii->lexicon is NULL");
  }
  return NULL;
}

static void
ii_buffer_value_init(grn_ctx *ctx, ii_buffer_value *value)
{
  value->sid = 0;
  value->weight = 0;
  value->p = NULL;
  value->len = 0;
  value->buf = NULL;
  value->cap = 0;
}

static void
ii_buffer_value_fin(grn_ctx *ctx, ii_buffer_value *value)
{
  if (value->buf) {
    GRN_FREE(value->buf);
  }
}

/*
 * ii_buffer_values_append appends a value to ii_buffer.
 * This function deep-copies the value if need_copy == GRN_TRUE.
 */
static void
ii_buffer_values_append(grn_ctx *ctx, grn_ii_buffer *ii_buffer,
                        unsigned int sid, uint32_t weight,
                        const char *p, uint32_t len, grn_bool need_copy)
{
  if (ii_buffer->nvalues == ii_buffer->max_nvalues) {
    unsigned int i;
    unsigned int new_max_nvalues = ii_buffer->max_nvalues * 2;
    unsigned int new_size;
    ii_buffer_value *new_values;
    if (new_max_nvalues == 0) {
      new_max_nvalues = 1;
    }
    new_size = new_max_nvalues * sizeof(ii_buffer_value);
    new_values = (ii_buffer_value *)GRN_REALLOC(ii_buffer->values, new_size);
    if (!new_values) {
      return;
    }
    for (i = ii_buffer->max_nvalues; i < new_max_nvalues; i++) {
      ii_buffer_value_init(ctx, &new_values[i]);
    }
    ii_buffer->values = new_values;
    ii_buffer->max_nvalues = new_max_nvalues;
  }

  {
    ii_buffer_value *value = &ii_buffer->values[ii_buffer->nvalues];
    if (need_copy) {
      if (len > value->cap) {
        char *new_buf = (char *)GRN_REALLOC(value->buf, len);
        if (!new_buf) {
          return;
        }
        value->buf = new_buf;
        value->cap = len;
      }
      grn_memcpy(value->buf, p, len);
      p = value->buf;
    }
    value->sid = sid;
    value->weight = weight;
    value->p = p;
    value->len = len;
    ii_buffer->nvalues++;
  }
}

grn_rc
grn_ii_buffer_append(grn_ctx *ctx, grn_ii_buffer *ii_buffer,
                     grn_id rid, unsigned int sid, grn_obj *value)
{
  if (rid != ii_buffer->last_rid) {
    if (ii_buffer->last_rid) {
      grn_ii_buffer_tokenize(ctx, ii_buffer, ii_buffer->last_rid);
    }
    ii_buffer->last_rid = rid;
  }
  ii_buffer_values_append(ctx, ii_buffer, sid, 0,
                          GRN_TEXT_VALUE(value), GRN_TEXT_LEN(value),
                          GRN_TRUE);
  return ctx->rc;
}

/*
 * grn_ii_buffer_commit completes tokenization and builds an inverted index
 * from data in a temporary file.
 */
grn_rc
grn_ii_buffer_commit(grn_ctx *ctx, grn_ii_buffer *ii_buffer)
{
  /* Tokenize the remaining values and free resources. */
  if (ii_buffer->last_rid && ii_buffer->nvalues) {
    grn_ii_buffer_tokenize(ctx, ii_buffer, ii_buffer->last_rid);
  }
  if (ii_buffer->block_pos) {
    grn_ii_buffer_flush(ctx, ii_buffer);
  }
  if (ii_buffer->tmpfd != -1) {
    grn_close(ii_buffer->tmpfd);
  }
  if (ii_buffer->block_buf) {
    GRN_FREE(ii_buffer->block_buf);
    ii_buffer->block_buf = NULL;
  }
  if (ii_buffer->counters) {
    GRN_FREE(ii_buffer->counters);
    ii_buffer->counters = NULL;
  }

  if (ii_buffer->update_buffer_size &&
      ii_buffer->update_buffer_size < 20) {
    if (ii_buffer->update_buffer_size < 10) {
      ii_buffer->update_buffer_size =
        ii_buffer->total_size >> (10 - ii_buffer->update_buffer_size);
    } else {
      ii_buffer->update_buffer_size =
        ii_buffer->total_size << (ii_buffer->update_buffer_size - 10);
    }
  }

  GRN_LOG(ctx, GRN_LOG_DEBUG,
          "nblocks=%d, update_buffer_size=%" GRN_FMT_INT64U,
          ii_buffer->nblocks, ii_buffer->update_buffer_size);

  datavec_init(ctx, ii_buffer->data_vectors, ii_buffer->ii->n_elements, 0, 0);
  grn_open(ii_buffer->tmpfd,
           ii_buffer->tmpfpath,
           O_RDONLY | GRN_OPEN_FLAG_BINARY);
  if (ii_buffer->tmpfd == -1) {
    ERRNO_ERR("failed to open path: <%s>", ii_buffer->tmpfpath);
    return ctx->rc;
  }
  {
    /* Fetch the first term of each block. */
    uint32_t i;
    for (i = 0; i < ii_buffer->nblocks; i++) {
      grn_ii_buffer_fetch(ctx, ii_buffer, &ii_buffer->blocks[i]);
    }
  }
  {
    ii_buffer_block **hits;
    if ((hits = GRN_MALLOCN(ii_buffer_block *, ii_buffer->nblocks))) {
      grn_id tid;
      grn_table_cursor *tc;
      tc = grn_table_cursor_open(ctx, ii_buffer->lexicon,
                                 NULL, 0, NULL, 0, 0, -1, II_BUFFER_ORDER);
      if (tc) {
        while ((tid = grn_table_cursor_next(ctx, tc)) != GRN_ID_NIL) {
          /*
           * Find blocks which contain the current term.
           * Then, merge the postings.
           */
          int nrests = 0;
          int nhits = 0;
          uint32_t i;
          for (i = 0; i < ii_buffer->nblocks; i++) {
            if (ii_buffer->blocks[i].tid == tid) {
              hits[nhits++] = &ii_buffer->blocks[i];
            }
            if (ii_buffer->blocks[i].tid) { nrests++; }
          }
          if (nhits) { grn_ii_buffer_merge(ctx, ii_buffer, tid, hits, nhits); }
          if (!nrests) { break; }
        }
        if (ii_buffer->packed_len) {
          grn_ii_buffer_chunk_flush(ctx, ii_buffer);
        }
        grn_table_cursor_close(ctx, tc);
      }
      GRN_FREE(hits);
    }
  }
  datavec_fin(ctx, ii_buffer->data_vectors);
  GRN_LOG(ctx, GRN_LOG_DEBUG,
          "tmpfile_size:%" GRN_FMT_INT64D " > total_chunk_size:%" GRN_FMT_SIZE,
          ii_buffer->filepos, ii_buffer->total_chunk_size);
  grn_close(ii_buffer->tmpfd);
  if (grn_unlink(ii_buffer->tmpfpath) == 0) {
    GRN_LOG(ctx, GRN_LOG_INFO,
            "[ii][buffer][commit] removed temporary path: <%s>",
            ii_buffer->tmpfpath);
  } else {
    ERRNO_ERR("[ii][buffer][commit] failed to remove temporary path: <%s>",
              ii_buffer->tmpfpath);
  }
  ii_buffer->tmpfd = -1;
  return ctx->rc;
}

grn_rc
grn_ii_buffer_close(grn_ctx *ctx, grn_ii_buffer *ii_buffer)
{
  uint32_t i;
  grn_table_flags flags;
  grn_table_get_info(ctx, ii_buffer->ii->lexicon, &flags, NULL, NULL, NULL,
                     NULL);
  if (ii_buffer->tmp_lexicon) {
    grn_obj_close(ctx, ii_buffer->tmp_lexicon);
  }
  if (ii_buffer->tmpfd != -1) {
    grn_close(ii_buffer->tmpfd);
    if (grn_unlink(ii_buffer->tmpfpath) == 0) {
      GRN_LOG(ctx, GRN_LOG_INFO,
              "[ii][buffer][close] removed temporary path: <%s>",
              ii_buffer->tmpfpath);
    } else {
      ERRNO_ERR("[ii][buffer][close] failed to remove temporary path: <%s>",
                ii_buffer->tmpfpath);
    }
  }
  if (ii_buffer->block_buf) {
    GRN_FREE(ii_buffer->block_buf);
  }
  if (ii_buffer->counters) {
    GRN_FREE(ii_buffer->counters);
  }
  if (ii_buffer->blocks) {
    for (i = 0; i < ii_buffer->nblocks; i++) {
      if (ii_buffer->blocks[i].buffer) {
        GRN_FREE(ii_buffer->blocks[i].buffer);
      }
    }
    GRN_FREE(ii_buffer->blocks);
  }
  if (ii_buffer->values) {
    for (i = 0; i < ii_buffer->max_nvalues; i++) {
      ii_buffer_value_fin(ctx, &ii_buffer->values[i]);
    }
    GRN_FREE(ii_buffer->values);
  }
  GRN_FREE(ii_buffer);
  return ctx->rc;
}

/*
 * grn_ii_buffer_parse tokenizes values to be indexed.
 *
 * For each record of the target table, grn_ii_buffer_parse makes a list of
 * target values and calls grn_ii_buffer_tokenize. To make a list of target
 * values, ii_buffer_values_append is called for each value. Note that
 * ii_buffer_values_append is called for each element for a vector.
 */
static void
grn_ii_buffer_parse(grn_ctx *ctx, grn_ii_buffer *ii_buffer,
                    grn_obj *target, int ncols, grn_obj **cols)
{
  grn_table_cursor  *tc;
  grn_obj *vobjs;
  if ((vobjs = GRN_MALLOCN(grn_obj, ncols))) {
    int i;
    for (i = 0; i < ncols; i++) {
      GRN_TEXT_INIT(&vobjs[i], 0);
    }
    if ((tc = grn_table_cursor_open(ctx, target,
                                    NULL, 0, NULL, 0, 0, -1,
                                    GRN_CURSOR_BY_ID))) {
      grn_id rid;
      while ((rid = grn_table_cursor_next(ctx, tc)) != GRN_ID_NIL) {
        unsigned int j;
        int sid;
        grn_obj **col;
        for (sid = 1, col = cols; sid <= ncols; sid++, col++) {
          grn_obj *rv = &vobjs[sid - 1];
          grn_obj_reinit_for(ctx, rv, *col);
          if (GRN_OBJ_TABLEP(*col)) {
            grn_table_get_key2(ctx, *col, rid, rv);
          } else {
            grn_obj_get_value(ctx, *col, rid, rv);
          }
          switch (rv->header.type) {
          case GRN_BULK :
            ii_buffer_values_append(ctx, ii_buffer, sid, 0,
                                    GRN_TEXT_VALUE(rv), GRN_TEXT_LEN(rv),
                                    GRN_FALSE);
            break;
          case GRN_UVECTOR :
            {
              unsigned int size;
              unsigned int elem_size;
              size = grn_uvector_size(ctx, rv);
              elem_size = grn_uvector_element_size(ctx, rv);
              for (j = 0; j < size; j++) {
                ii_buffer_values_append(ctx, ii_buffer, sid, 0,
                                        GRN_BULK_HEAD(rv) + (elem_size * j),
                                        elem_size, GRN_FALSE);
              }
            }
            break;
          case GRN_VECTOR :
            if (rv->u.v.body) {
              int j;
              int n_sections = rv->u.v.n_sections;
              grn_section *sections = rv->u.v.sections;
              const char *head = GRN_BULK_HEAD(rv->u.v.body);
              for (j = 0; j < n_sections; j++) {
                grn_section *section = sections + j;
                if (section->length == 0) {
                  continue;
                }
                ii_buffer_values_append(ctx, ii_buffer, sid, section->weight,
                                        head + section->offset,
                                        section->length, GRN_FALSE);
              }
            }
            break;
          default :
            ERR(GRN_INVALID_ARGUMENT,
                "[index] invalid object assigned as value");
            break;
          }
        }
        grn_ii_buffer_tokenize(ctx, ii_buffer, rid);
      }
      grn_table_cursor_close(ctx, tc);
    }
    for (i = 0; i < ncols; i++) {
      GRN_OBJ_FIN(ctx, &vobjs[i]);
    }
    GRN_FREE(vobjs);
  }
}

grn_rc
grn_ii_build(grn_ctx *ctx, grn_ii *ii, uint64_t sparsity)
{
  grn_ii_buffer *ii_buffer;

  {
    /* Do nothing if there are no targets. */
    grn_obj *data_table = grn_ctx_at(ctx, DB_OBJ(ii)->range);
    if (!data_table) {
      return ctx->rc;
    }
    if (grn_table_size(ctx, data_table) == 0) {
      return ctx->rc;
    }
  }

  ii_buffer = grn_ii_buffer_open(ctx, ii, sparsity);
  if (ii_buffer) {
    grn_id *source = (grn_id *)ii->obj.source;
    if (ii->obj.source_size && ii->obj.source) {
      int ncols = ii->obj.source_size / sizeof(grn_id);
      grn_obj **cols = GRN_MALLOCN(grn_obj *, ncols);
      if (cols) {
        int i;
        for (i = 0; i < ncols; i++) {
          if (!(cols[i] = grn_ctx_at(ctx, source[i]))) { break; }
        }
        if (i == ncols) { /* All the source columns are available. */
          grn_obj *target = cols[0];
          if (!GRN_OBJ_TABLEP(target)) {
            target = grn_ctx_at(ctx, target->header.domain);
          }
          if (target) {
            grn_ii_buffer_parse(ctx, ii_buffer, target, ncols, cols);
            grn_ii_buffer_commit(ctx, ii_buffer);
          } else {
            ERR(GRN_INVALID_ARGUMENT, "failed to resolve the target");
          }
        } else {
          ERR(GRN_INVALID_ARGUMENT, "failed to resolve a column (%d)", i);
        }
        GRN_FREE(cols);
      }
    } else {
      ERR(GRN_INVALID_ARGUMENT, "ii->obj.source is void");
    }
    grn_ii_buffer_close(ctx, ii_buffer);
  }
  return ctx->rc;
}

/*
 * ==========================================================================
 * The following part provides constants, structures and functions for static
 * indexing.
 * ==========================================================================
 */

#define GRN_II_BUILDER_BUFFER_CHUNK_SIZE      (S_CHUNK >> 2)

#define GRN_II_BUILDER_MAX_LEXICON_CACHE_SIZE (1 << 24)

#define GRN_II_BUILDER_MIN_BLOCK_THRESHOLD    1
#define GRN_II_BUILDER_MAX_BLOCK_THRESHOLD    (1 << 28)

#define GRN_II_BUILDER_MIN_FILE_BUF_SIZE      (1 << 12)
#define GRN_II_BUILDER_MAX_FILE_BUF_SIZE      (1 << 30)

#define GRN_II_BUILDER_MIN_BLOCK_BUF_SIZE     (1 << 12)
#define GRN_II_BUILDER_MAX_BLOCK_BUF_SIZE     (1 << 30)

#define GRN_II_BUILDER_MIN_CHUNK_THRESHOLD    1
#define GRN_II_BUILDER_MAX_CHUNK_THRESHOLD    (1 << 28)

#define GRN_II_BUILDER_MIN_BUFFER_MAX_N_TERMS 1
#define GRN_II_BUILDER_MAX_BUFFER_MAX_N_TERMS \
  ((S_SEGMENT - sizeof(buffer_header)) / sizeof(buffer_term))

struct grn_ii_builder_options {
  uint32_t lexicon_cache_size; /* Cache size of temporary lexicon */
  /* A block is flushed if builder->n reaches this value. */
  uint32_t block_threshold;
  uint32_t file_buf_size;      /* Buffer size for buffered output */
  uint32_t block_buf_size;     /* Buffer size for buffered input */
  /* A chunk is flushed if chunk->n reaches this value. */
  uint32_t chunk_threshold;
  uint32_t buffer_max_n_terms; /* Maximum number of terms in each buffer */
};

static const grn_ii_builder_options grn_ii_builder_default_options = {
  0x80000,   /* lexicon_cache_size */
  0x4000000, /* block_threshold */
  0x10000,   /* file_buf_size */
  0x10000,   /* block_buf_size */
  0x1000,    /* chunk_threshold */
  0x3000,    /* buffer_max_n_terms */
};

/* grn_ii_builder_options_init fills options with the default options. */
void
grn_ii_builder_options_init(grn_ii_builder_options *options)
{
  *options = grn_ii_builder_default_options;
}

/* grn_ii_builder_options_fix fixes out-of-range options. */
static void
grn_ii_builder_options_fix(grn_ii_builder_options *options)
{
  if (options->lexicon_cache_size > GRN_II_BUILDER_MAX_LEXICON_CACHE_SIZE) {
    options->lexicon_cache_size = GRN_II_BUILDER_MAX_LEXICON_CACHE_SIZE;
  }

  if (options->block_threshold < GRN_II_BUILDER_MIN_BLOCK_THRESHOLD) {
    options->block_threshold = GRN_II_BUILDER_MIN_BLOCK_THRESHOLD;
  }
  if (options->block_threshold > GRN_II_BUILDER_MAX_BLOCK_THRESHOLD) {
    options->block_threshold = GRN_II_BUILDER_MAX_BLOCK_THRESHOLD;
  }

  if (options->file_buf_size < GRN_II_BUILDER_MIN_FILE_BUF_SIZE) {
    options->file_buf_size = GRN_II_BUILDER_MIN_FILE_BUF_SIZE;
  }
  if (options->file_buf_size > GRN_II_BUILDER_MAX_FILE_BUF_SIZE) {
    options->file_buf_size = GRN_II_BUILDER_MAX_FILE_BUF_SIZE;
  }

  if (options->block_buf_size < GRN_II_BUILDER_MIN_BLOCK_BUF_SIZE) {
    options->block_buf_size = GRN_II_BUILDER_MIN_BLOCK_BUF_SIZE;
  }
  if (options->block_buf_size > GRN_II_BUILDER_MAX_BLOCK_BUF_SIZE) {
    options->block_buf_size = GRN_II_BUILDER_MAX_BLOCK_BUF_SIZE;
  }

  if (options->chunk_threshold < GRN_II_BUILDER_MIN_CHUNK_THRESHOLD) {
    options->chunk_threshold = GRN_II_BUILDER_MIN_CHUNK_THRESHOLD;
  }
  if (options->chunk_threshold > GRN_II_BUILDER_MAX_CHUNK_THRESHOLD) {
    options->chunk_threshold = GRN_II_BUILDER_MAX_CHUNK_THRESHOLD;
  }

  if (options->buffer_max_n_terms < GRN_II_BUILDER_MIN_BUFFER_MAX_N_TERMS) {
    options->buffer_max_n_terms = GRN_II_BUILDER_MIN_BUFFER_MAX_N_TERMS;
  }
  if (options->buffer_max_n_terms > GRN_II_BUILDER_MAX_BUFFER_MAX_N_TERMS) {
    options->buffer_max_n_terms = GRN_II_BUILDER_MAX_BUFFER_MAX_N_TERMS;
  }
}

#define GRN_II_BUILDER_TERM_INPLACE_SIZE\
  (sizeof(grn_ii_builder_term) - (uintptr_t)&((grn_ii_builder_term *)0)->dummy)

typedef struct {
  grn_id   rid;    /* Last record ID */
  uint32_t sid;    /* Last section ID */
  /* Last position (GRN_OBJ_WITH_POSITION) or frequency. */
  uint32_t pos_or_freq;
  uint32_t offset; /* Buffer write offset */
  uint32_t size;   /* Buffer size */
  uint32_t dummy;  /* Padding */
  uint8_t  *buf;   /* Buffer (to be freed) */
} grn_ii_builder_term;

/* grn_ii_builder_term_is_inplace returns whether a term buffer is inplace. */
grn_inline static grn_bool
grn_ii_builder_term_is_inplace(grn_ii_builder_term *term)
{
  return term->size == GRN_II_BUILDER_TERM_INPLACE_SIZE;
}

/* grn_ii_builder_term_get_buf returns a term buffer. */
grn_inline static uint8_t *
grn_ii_builder_term_get_buf(grn_ii_builder_term *term)
{
  if (grn_ii_builder_term_is_inplace(term)) {
    return (uint8_t *)&term->dummy;
  } else {
    return term->buf;
  }
}

/*
 * grn_ii_builder_term_init initializes a term. Note that an initialized term
 * must be finalized by grn_ii_builder_term_fin.
 */
static void
grn_ii_builder_term_init(grn_ctx *ctx, grn_ii_builder_term *term)
{
  term->rid = GRN_ID_NIL;
  term->sid = 0;
  term->pos_or_freq = 0;
  term->offset = 0;
  term->size = GRN_II_BUILDER_TERM_INPLACE_SIZE;
}

/* grn_ii_builder_term_fin finalizes a term. */
static void
grn_ii_builder_term_fin(grn_ctx *ctx, grn_ii_builder_term *term)
{
  if (!grn_ii_builder_term_is_inplace(term)) {
    GRN_FREE(term->buf);
  }
}

/* grn_ii_builder_term_reinit reinitializes a term. */
static void
grn_ii_builder_term_reinit(grn_ctx *ctx, grn_ii_builder_term *term)
{
  grn_ii_builder_term_fin(ctx, term);
  grn_ii_builder_term_init(ctx, term);
}

/* grn_ii_builder_term_extend extends a term buffer. */
static grn_rc
grn_ii_builder_term_extend(grn_ctx *ctx, grn_ii_builder_term *term)
{
  uint8_t *buf;
  uint32_t size = term->size * 2;
  if (grn_ii_builder_term_is_inplace(term)) {
    buf = (uint8_t *)GRN_MALLOC(size);
    if (!buf) {
      ERR(GRN_NO_MEMORY_AVAILABLE,
          "failed to allocate memory for term buffer: size = %u", size);
      return ctx->rc;
    }
    grn_memcpy(buf, &term->dummy, term->offset);
  } else {
    buf = (uint8_t *)GRN_REALLOC(term->buf, size);
    if (!buf) {
      ERR(GRN_NO_MEMORY_AVAILABLE,
          "failed to reallocate memory for term buffer: size = %u", size);
      return ctx->rc;
    }
  }
  term->buf = buf;
  term->size = size;
  return GRN_SUCCESS;
}

/* grn_ii_builder_term_append appends an integer to a term buffer. */
grn_inline static grn_rc
grn_ii_builder_term_append(grn_ctx *ctx, grn_ii_builder_term *term,
                           uint64_t value)
{
  uint8_t *p;
  if (value < (uint64_t)1 << 5) {
    if (term->offset + 1 > term->size) {
      grn_rc rc = grn_ii_builder_term_extend(ctx, term);
      if (rc != GRN_SUCCESS) {
        return rc;
      }
    }
    p = grn_ii_builder_term_get_buf(term) + term->offset;
    p[0] = (uint8_t)value;
    term->offset++;
    return GRN_SUCCESS;
  } else if (value < (uint64_t)1 << 13) {
    if (term->offset + 2 > term->size) {
      grn_rc rc = grn_ii_builder_term_extend(ctx, term);
      if (rc != GRN_SUCCESS) {
        return rc;
      }
    }
    p = grn_ii_builder_term_get_buf(term) + term->offset;
    p[0] = (uint8_t)((value & 0x1f) | (1 << 5));
    p[1] = (uint8_t)(value >> 5);
    term->offset += 2;
    return GRN_SUCCESS;
  } else {
    uint8_t i, n;
    if (value < (uint64_t)1 << 21) {
      n = 3;
    } else if (value < (uint64_t)1 << 29) {
      n = 4;
    } else if (value < (uint64_t)1 << 37) {
      n = 5;
    } else if (value < (uint64_t)1 << 45) {
      n = 6;
    } else if (value < (uint64_t)1 << 53) {
      n = 7;
    } else {
      n = 8;
    }
    if (term->offset + n > term->size) {
      grn_rc rc = grn_ii_builder_term_extend(ctx, term);
      if (rc != GRN_SUCCESS) {
        return rc;
      }
    }
    p = grn_ii_builder_term_get_buf(term) + term->offset;
    p[0] = (uint8_t)(value & 0x1f) | ((n - 1) << 5);
    value >>= 5;
    for (i = 1; i < n; i++) {
      p[i] = (uint8_t)value;
      value >>= 8;
    }
    term->offset += n;
    return GRN_SUCCESS;
  }
}

typedef struct {
  uint64_t offset; /* File offset */
  uint32_t rest;   /* Remaining size */
  uint8_t  *buf;   /* Buffer (to be freed) */
  uint8_t  *cur;   /* Current pointer */
  uint8_t  *end;   /* End pointer */
  uint32_t tid;    /* Term ID */
} grn_ii_builder_block;

/*
 * grn_ii_builder_block_init initializes a block. Note that an initialized
 * block must be finalized by grn_ii_builder_block_fin.
 */
static void
grn_ii_builder_block_init(grn_ctx *ctx, grn_ii_builder_block *block)
{
  block->offset = 0;
  block->rest = 0;
  block->buf = NULL;
  block->cur = NULL;
  block->end = NULL;
  block->tid = GRN_ID_NIL;
}

/* grn_ii_builder_block_fin finalizes a block. */
static void
grn_ii_builder_block_fin(grn_ctx *ctx, grn_ii_builder_block *block)
{
  if (block->buf) {
    GRN_FREE(block->buf);
  }
}

/*
 * grn_ii_builder_block_next reads the next integer. Note that this function
 * returns GRN_END_OF_DATA if it reaches the end of a block.
 */
grn_inline static grn_rc
grn_ii_builder_block_next(grn_ctx *ctx, grn_ii_builder_block *block,
                          uint64_t *value)
{
  uint8_t n;
  if (block->cur == block->end) {
    return GRN_END_OF_DATA;
  }
  n = (*block->cur >> 5) + 1;
  if (n > block->end - block->cur) {
    return GRN_END_OF_DATA;
  }
  *value = 0;
  switch (n) {
  case 8 :
    *value |= (uint64_t)block->cur[7] << 53;
  case 7 :
    *value |= (uint64_t)block->cur[6] << 45;
  case 6 :
    *value |= (uint64_t)block->cur[5] << 37;
  case 5 :
    *value |= (uint64_t)block->cur[4] << 29;
  case 4 :
    *value |= (uint64_t)block->cur[3] << 21;
  case 3 :
    *value |= (uint64_t)block->cur[2] << 13;
  case 2 :
    *value |= (uint64_t)block->cur[1] << 5;
  case 1 :
    *value |= block->cur[0] & 0x1f;
    break;
  }
  block->cur += n;
  return GRN_SUCCESS;
}

typedef struct {
  grn_ii   *ii;          /* Inverted index */
  uint32_t buf_id;       /* Buffer ID */
  uint32_t buf_seg_id;   /* Buffer segment ID */
  buffer   *buf;         /* Buffer (to be unreferenced) */
  uint32_t chunk_id;     /* Chunk ID */
  uint32_t chunk_seg_id; /* Chunk segment ID */
  uint8_t  *chunk;       /* Chunk (to be unreferenced) */
  uint32_t chunk_offset; /* Chunk write position */
  uint32_t chunk_size;   /* Chunk size */
} grn_ii_builder_buffer;

/*
 * grn_ii_builder_buffer_init initializes a buffer. Note that a buffer must be
 * finalized by grn_ii_builder_buffer_fin.
 */
static void
grn_ii_builder_buffer_init(grn_ctx *ctx, grn_ii_builder_buffer *buf,
                           grn_ii *ii)
{
  buf->ii = ii;
  buf->buf_id = 0;
  buf->buf_seg_id = 0;
  buf->buf = NULL;
  buf->chunk_id = 0;
  buf->chunk_seg_id = 0;
  buf->chunk = NULL;
  buf->chunk_offset = 0;
  buf->chunk_size = 0;
}

/* grn_ii_builder_buffer_fin finalizes a buffer. */
static void
grn_ii_builder_buffer_fin(grn_ctx *ctx, grn_ii_builder_buffer *buf)
{
  if (buf->buf) {
    grn_io_seg_unref(ctx, buf->ii->seg, buf->buf_seg_id);
  }
  if (buf->chunk) {
    grn_io_seg_unref(ctx, buf->ii->chunk, buf->chunk_seg_id);
  }
}

/* grn_ii_builder_buffer_is_assigned returns whether a buffer is assigned. */
static grn_bool
grn_ii_builder_buffer_is_assigned(grn_ctx *ctx, grn_ii_builder_buffer *buf)
{
  return buf->buf != NULL;
}

/* grn_ii_builder_buffer_assign assigns a buffer. */
static grn_rc
grn_ii_builder_buffer_assign(grn_ctx *ctx, grn_ii_builder_buffer *buf,
                             size_t min_chunk_size)
{
  void *seg;
  size_t chunk_size;
  grn_rc rc;

  /* Create a buffer. */
  buf->buf_id = GRN_II_PSEG_NOT_ASSIGNED;
  rc = buffer_segment_new(ctx, buf->ii, &buf->buf_id);
  if (rc != GRN_SUCCESS) {
    if (ctx->rc != GRN_SUCCESS) {
      ERR(rc,
          "[ii][builder][buffer][assign] "
          "failed to allocate segment for buffer");
    }
    return rc;
  }
  buf->buf_seg_id = grn_ii_get_buffer_pseg_inline(buf->ii, buf->buf_id);
  seg = grn_io_seg_ref(ctx, buf->ii->seg, buf->buf_seg_id);
  if (!seg) {
    if (ctx->rc == GRN_SUCCESS) {
      ERR(GRN_UNKNOWN_ERROR,
          "[ii][builder][buffer][assign] "
          "failed to access buffer segment: buffer_id=<%u> segment_id=<%u>",
          buf->buf_id, buf->buf_seg_id);
    }
    return ctx->rc;
  }
  buf->buf = (buffer *)seg;

  /* Create a chunk. */
  chunk_size = GRN_II_BUILDER_BUFFER_CHUNK_SIZE;
  while (chunk_size < min_chunk_size) {
    chunk_size *= 2;
  }
  rc = chunk_new(ctx, buf->ii, &buf->chunk_id, chunk_size);
  if (rc != GRN_SUCCESS) {
    return rc;
  }

  const size_t seg_offset =
    (buf->chunk_id & ((1 << GRN_II_N_CHUNK_VARIATION) - 1)) <<
    GRN_II_W_LEAST_CHUNK;
  const uint32_t chunk_capacity =
    buf->ii->chunk->header->segment_size - seg_offset;
  if (chunk_capacity < chunk_size) {
    ERR(GRN_NOT_ENOUGH_SPACE,
        "[ii][builder][buffer][assign] "
        "too large chunk size: "
        "chunk_size=<%" GRN_FMT_SIZE "> "
        "chunk_capacity=<%u> "
        "chunk_id=<%u> "
        "segment_id=<%u>",
        chunk_size,
        chunk_capacity,
        buf->chunk_id,
        buf->chunk_seg_id);
    return ctx->rc;
  }

  buf->chunk_seg_id = buf->chunk_id >> GRN_II_N_CHUNK_VARIATION;
  seg = grn_io_seg_ref(ctx, buf->ii->chunk, buf->chunk_seg_id);
  if (!seg) {
    if (ctx->rc == GRN_SUCCESS) {
      ERR(GRN_UNKNOWN_ERROR,
          "[ii][builder][buffer][assign] "
          "failed to access chunk segment: chunk_id=<%u> segment_id=<%u>",
          buf->chunk_id, buf->chunk_seg_id);
    }
    return ctx->rc;
  }
  buf->chunk = ((uint8_t *)seg) + seg_offset;
  buf->chunk_offset = 0;
  buf->chunk_size = chunk_size;

  buf->buf->header.chunk = buf->chunk_id;
  buf->buf->header.chunk_size = chunk_size;
  buf->buf->header.buffer_free = S_SEGMENT - sizeof(buffer_header);
  buf->buf->header.nterms = 0;
  buf->buf->header.nterms_void = 0;
  buf->ii->header.common->total_chunk_size += chunk_size;
  return GRN_SUCCESS;
}

/* grn_ii_builder_buffer_flush flushes a buffer. */
static grn_rc
grn_ii_builder_buffer_flush(grn_ctx *ctx, grn_ii_builder_buffer *buf)
{
  grn_ii *ii;

  buf->buf->header.buffer_free = S_SEGMENT - sizeof(buffer_header) -
                                 buf->buf->header.nterms * sizeof(buffer_term);
  GRN_LOG(ctx, GRN_LOG_DEBUG,
          "[ii][builder][buffer][flush] "
          "n_terms=<%u> "
          "chunk_offset=<%u> "
          "chunk_size=<%u> "
          "total=<%" GRN_FMT_INT64U "KB>",
          buf->buf->header.nterms,
          buf->chunk_offset,
          buf->buf->header.chunk_size,
          buf->ii->header.common->total_chunk_size >> 10);

  ii = buf->ii;
  grn_ii_builder_buffer_fin(ctx, buf);
  grn_ii_builder_buffer_init(ctx, buf, ii);
  return GRN_SUCCESS;
}

typedef struct {
  grn_id   tid;         /* Term ID */
  uint32_t n;           /* Number of integers in buffers */
  grn_id   rid;         /* Record ID */
  uint32_t rid_gap;     /* Record ID gap */
  uint64_t pos_sum;     /* Sum of position gaps */

  uint32_t offset;      /* Write offset */
  uint32_t size;        /* Buffer size */
  grn_id   *rid_buf;    /* Buffer for record IDs (to be freed) */
  uint32_t *sid_buf;    /* Buffer for section IDs (to be freed) */
  uint32_t *freq_buf;   /* Buffer for frequencies (to be freed) */
  uint32_t *weight_buf; /* Buffer for weights (to be freed) */

  uint32_t pos_offset;  /* Write offset of pos_buf */
  uint32_t pos_size;    /* Buffer size of pos_buf */
  uint32_t *pos_buf;    /* Buffer for positions (to be freed) */

  size_t   enc_offset;  /* Write offset of enc_buf */
  size_t   enc_size;    /* Buffer size of enc_buf */
  uint8_t  *enc_buf;    /* Buffer for encoded data (to be freed) */
} grn_ii_builder_chunk;

/*
 * grn_ii_builder_chunk_init initializes a chunk. Note that an initialized
 * chunk must be finalized by grn_ii_builder_chunk_fin.
 */
static void
grn_ii_builder_chunk_init(grn_ctx *ctx, grn_ii_builder_chunk *chunk)
{
  chunk->tid = GRN_ID_NIL;
  chunk->n = 0;
  chunk->rid = GRN_ID_NIL;
  chunk->rid_gap = 0;
  chunk->pos_sum = 0;

  chunk->offset = 0;
  chunk->size = 0;
  chunk->rid_buf = NULL;
  chunk->sid_buf = NULL;
  chunk->freq_buf = NULL;
  chunk->weight_buf = NULL;

  chunk->pos_offset = 0;
  chunk->pos_size = 0;
  chunk->pos_buf = NULL;

  chunk->enc_offset = 0;
  chunk->enc_size = 0;
  chunk->enc_buf = NULL;
}

/* grn_ii_builder_chunk_fin finalizes a chunk. */
static void
grn_ii_builder_chunk_fin(grn_ctx *ctx, grn_ii_builder_chunk *chunk)
{
  if (chunk->enc_buf) {
    GRN_FREE(chunk->enc_buf);
  }
  if (chunk->pos_buf) {
    GRN_FREE(chunk->pos_buf);
  }
  if (chunk->weight_buf) {
    GRN_FREE(chunk->weight_buf);
  }
  if (chunk->freq_buf) {
    GRN_FREE(chunk->freq_buf);
  }
  if (chunk->sid_buf) {
    GRN_FREE(chunk->sid_buf);
  }
  if (chunk->rid_buf) {
    GRN_FREE(chunk->rid_buf);
  }
}

/*
 * grn_ii_builder_chunk_clear clears stats except rid and buffers except
 * enc_buf.
 */
static void
grn_ii_builder_chunk_clear(grn_ctx *ctx, grn_ii_builder_chunk *chunk)
{
  chunk->n = 0;
  chunk->rid_gap = 0;
  chunk->pos_sum = 0;
  chunk->offset = 0;
  chunk->pos_offset = 0;
}

/*
 * grn_ii_builder_chunk_extend_bufs extends buffers except pos_buf and enc_buf.
 */
static grn_rc
grn_ii_builder_chunk_extend_bufs(grn_ctx *ctx, grn_ii_builder_chunk *chunk,
                                 uint32_t ii_flags)
{
  uint32_t *buf;
  uint32_t size = chunk->size ? chunk->size * 2 : 1;
  size_t n_bytes = size * sizeof(uint32_t);

  buf = (uint32_t *)GRN_REALLOC(chunk->rid_buf, n_bytes);
  if (!buf) {
    ERR(GRN_NO_MEMORY_AVAILABLE,
        "failed to allocate memory for record IDs: n_bytes = %" GRN_FMT_SIZE,
        n_bytes);
    return ctx->rc;
  }
  chunk->rid_buf = buf;

  if (ii_flags & GRN_OBJ_WITH_SECTION) {
    buf = (uint32_t *)GRN_REALLOC(chunk->sid_buf, n_bytes);
    if (!buf) {
      ERR(GRN_NO_MEMORY_AVAILABLE,
          "failed to allocate memory for section IDs:"
          " n_bytes = %" GRN_FMT_SIZE,
          n_bytes);
      return ctx->rc;
    }
    chunk->sid_buf = buf;
  }

  buf = (uint32_t *)GRN_REALLOC(chunk->freq_buf, n_bytes);
  if (!buf) {
    ERR(GRN_NO_MEMORY_AVAILABLE,
        "failed to allocate memory for frequencies: n_bytes = %" GRN_FMT_SIZE,
        n_bytes);
    return ctx->rc;
  }
  chunk->freq_buf = buf;

  if (ii_flags & GRN_OBJ_WITH_WEIGHT) {
    buf = (uint32_t *)GRN_REALLOC(chunk->weight_buf, n_bytes);
    if (!buf) {
      ERR(GRN_NO_MEMORY_AVAILABLE,
          "failed to allocate memory for weights: n_bytes = %" GRN_FMT_SIZE,
          n_bytes);
      return ctx->rc;
    }
    chunk->weight_buf = buf;
  }

  chunk->size = size;
  return GRN_SUCCESS;
}

/* grn_ii_builder_chunk_extend_pos_buf extends pos_buf. */
static grn_rc
grn_ii_builder_chunk_extend_pos_buf(grn_ctx *ctx, grn_ii_builder_chunk *chunk)
{
  uint32_t *buf;
  uint32_t size = chunk->pos_size ? chunk->pos_size * 2 : 1;
  size_t n_bytes = size * sizeof(uint32_t);
  buf = (uint32_t *)GRN_REALLOC(chunk->pos_buf, n_bytes);
  if (!buf) {
    ERR(GRN_NO_MEMORY_AVAILABLE,
        "failed to allocate memory for positions: n_bytes = %" GRN_FMT_SIZE,
        n_bytes);
    return ctx->rc;
  }
  chunk->pos_buf = buf;
  chunk->pos_size = size;
  return GRN_SUCCESS;
}

/*
 * grn_ii_builder_chunk_reserve_enc_buf estimates a size that is enough to
 * store encoded data and allocates memory to enc_buf.
 */
static grn_rc
grn_ii_builder_chunk_reserve_enc_buf(grn_ctx *ctx, grn_ii_builder_chunk *chunk,
                                     uint32_t n_cinfos)
{
  size_t rich_size = (chunk->n + 4) * sizeof(uint32_t) +
                     n_cinfos * sizeof(chunk_info);
  if (chunk->enc_size < rich_size) {
    size_t size = chunk->enc_size ? chunk->enc_size * 2 : 1;
    uint8_t *buf;
    while (size < rich_size) {
      size *= 2;
    }
    buf = GRN_REALLOC(chunk->enc_buf, size);
    if (!buf) {
      ERR(GRN_NO_MEMORY_AVAILABLE,
          "failed to allocate memory for encoding: size = %" GRN_FMT_SIZE,
          size);
      return ctx->rc;
    }
    chunk->enc_buf = buf;
    chunk->enc_size = size;
  }
  chunk->enc_offset = 0;
  return GRN_SUCCESS;
}

/* grn_ii_builder_chunk_encode encodes a chunk buffer. */
static void
grn_ii_builder_chunk_encode_buf(grn_ctx *ctx, grn_ii_builder_chunk *chunk,
                                uint32_t *values, uint32_t n_values,
                                grn_bool use_p_enc)
{
  uint8_t *p = chunk->enc_buf + chunk->enc_offset;
  uint32_t i;
  if (use_p_enc) {
    uint8_t freq[33];
    uint32_t buf[UNIT_SIZE];
    while (n_values >= UNIT_SIZE) {
      memset(freq, 0, 33);
      for (i = 0; i < UNIT_SIZE; i++) {
        buf[i] = values[i];
        if (buf[i]) {
          uint32_t w;
          GRN_BIT_SCAN_REV(buf[i], w);
          freq[w + 1]++;
        } else {
          freq[0]++;
        }
      }
      p = pack(buf, UNIT_SIZE, freq, p);
      values += UNIT_SIZE;
      n_values -= UNIT_SIZE;
    }
    if (n_values) {
      memset(freq, 0, 33);
      for (i = 0; i < n_values; i++) {
        buf[i] = values[i];
        if (buf[i]) {
          uint32_t w;
          GRN_BIT_SCAN_REV(buf[i], w);
          freq[w + 1]++;
        } else {
          freq[0]++;
        }
      }
      p = pack(buf, n_values, freq, p);
    }
  } else {
    for (i = 0; i < n_values; i++) {
      GRN_B_ENC(values[i], p);
    }
  }
  chunk->enc_offset = p - chunk->enc_buf;
}

/* grn_ii_builder_chunk_encode encodes a chunk. */
static grn_rc
grn_ii_builder_chunk_encode(grn_ctx *ctx, grn_ii_builder_chunk *chunk,
                            chunk_info *cinfos, uint32_t n_cinfos)
{
  grn_rc rc;
  uint8_t *p;
  uint8_t shift = 0, use_p_enc_flags = 0;
  uint8_t rid_use_p_enc, rest_use_p_enc, pos_use_p_enc = 0;

  /* Choose an encoding. */
  rid_use_p_enc = chunk->offset >= 16 && chunk->offset > (chunk->rid >> 8);
  use_p_enc_flags |= rid_use_p_enc << shift++;
  rest_use_p_enc = chunk->offset >= 3;
  if (chunk->sid_buf) {
    use_p_enc_flags |= rest_use_p_enc << shift++;
  }
  use_p_enc_flags |= rest_use_p_enc << shift++;
  if (chunk->weight_buf) {
    use_p_enc_flags |= rest_use_p_enc << shift++;
  }
  if (chunk->pos_buf) {
    pos_use_p_enc = chunk->pos_offset >= 32 &&
                    chunk->pos_offset > (chunk->pos_sum >> 13);
    use_p_enc_flags |= pos_use_p_enc << shift++;
  }

  rc = grn_ii_builder_chunk_reserve_enc_buf(ctx, chunk, n_cinfos);
  if (rc != GRN_SUCCESS) {
    return rc;
  }

  /* Encode a header. */
  p = chunk->enc_buf;
  if (n_cinfos > 0) {
    uint32_t i;
    GRN_B_ENC(n_cinfos, p);
    for (i = 0; i < n_cinfos; i++) {
      GRN_B_ENC(cinfos[i].segno, p);
      GRN_B_ENC(cinfos[i].size, p);
      GRN_B_ENC(cinfos[i].dgap, p);
    }
  }
  if (use_p_enc_flags) {
    GRN_B_ENC(use_p_enc_flags << 1, p);
    GRN_B_ENC(chunk->offset, p);
    if (chunk->pos_buf) {
      GRN_B_ENC(chunk->pos_offset - chunk->offset, p);
    }
  } else {
    GRN_B_ENC((chunk->offset << 1) | 1, p);
  }
  chunk->enc_offset = p - chunk->enc_buf;

  /* Encode a body. */
  grn_ii_builder_chunk_encode_buf(ctx, chunk, chunk->rid_buf, chunk->offset,
                                  rid_use_p_enc);
  if (chunk->sid_buf) {
    grn_ii_builder_chunk_encode_buf(ctx, chunk, chunk->sid_buf, chunk->offset,
                                    rest_use_p_enc);
  }
  grn_ii_builder_chunk_encode_buf(ctx, chunk, chunk->freq_buf, chunk->offset,
                                  rest_use_p_enc);
  if (chunk->weight_buf) {
    grn_ii_builder_chunk_encode_buf(ctx, chunk, chunk->weight_buf,
                                    chunk->offset, rest_use_p_enc);
  }
  if (chunk->pos_buf) {
    grn_ii_builder_chunk_encode_buf(ctx, chunk, chunk->pos_buf,
                                    chunk->pos_offset, pos_use_p_enc);
  }

  return GRN_SUCCESS;
}

typedef struct {
  grn_ii                 *ii;     /* Building inverted index */
  grn_ii_builder_options options; /* Options */

  grn_obj  *src_table; /* Source table */
  grn_obj  **srcs;     /* Source columns (to be freed) */
  grn_obj  **src_token_columns; /* Source token columns (to be freed) */
  uint32_t n_srcs;     /* Number of source columns */
  uint8_t  sid_bits;   /* Number of bits for section ID */
  uint64_t sid_mask;   /* Mask bits for section ID */

  grn_obj  *lexicon;    /* Block lexicon (to be closed) */
  grn_bool have_tokenizer;  /* Whether lexicon has tokenizer */
  bool have_normalizers; /* Whether lexicon has at least one normalizers */

  uint32_t n;   /* Number of integers appended to the current block */
  grn_id   rid; /* Record ID */
  uint32_t sid; /* Section ID */
  uint32_t pos; /* Position */

  grn_ii_builder_term *terms;      /* Terms (to be freed) */
  uint32_t            n_terms;     /* Number of distinct terms */
  uint32_t            max_n_terms; /* Maximum number of distinct terms */
  uint32_t            terms_size;  /* Buffer size of terms */

  /* A temporary file to save blocks. */
  char    path[PATH_MAX];   /* File path */
  int     fd;               /* File descriptor (to be closed) */
  uint8_t *file_buf;        /* File buffer for buffered output (to be freed) */
  uint32_t file_buf_offset; /* File buffer write offset */

  grn_ii_builder_block *blocks;     /* Blocks (to be freed) */
  uint32_t             n_blocks;    /* Number of blocks */
  uint32_t             blocks_size; /* Buffer size of blocks */

  grn_ii_builder_buffer buf;   /* Buffer (to be finalized) */
  grn_ii_builder_chunk  chunk; /* Chunk (to be finalized) */

  uint32_t   df;          /* Document frequency (number of sections) */
  chunk_info *cinfos;     /* Chunk headers (to be freed) */
  uint32_t   n_cinfos;    /* Number of chunks */
  uint32_t   cinfos_size; /* Size of cinfos */
} grn_ii_builder;

/*
 * grn_ii_builder_init initializes a builder. Note that an initialized builder
 * must be finalized by grn_ii_builder_fin.
 */
static grn_rc
grn_ii_builder_init(grn_ctx *ctx, grn_ii_builder *builder,
                    grn_ii *ii, const grn_ii_builder_options *options)
{
  builder->ii = ii;
  builder->options = *options;
  if (grn_ii_builder_block_threshold_force > 0) {
    builder->options.block_threshold = grn_ii_builder_block_threshold_force;
  }
  grn_ii_builder_options_fix(&builder->options);

  builder->src_table = NULL;
  builder->srcs = NULL;
  builder->src_token_columns = NULL;
  builder->n_srcs = 0;
  builder->sid_bits = 0;
  builder->sid_mask = 0;

  builder->lexicon = NULL;
  builder->have_tokenizer = GRN_FALSE;
  builder->have_normalizers = false;

  builder->n = 0;
  builder->rid = GRN_ID_NIL;
  builder->sid = 0;
  builder->pos = 0;

  builder->terms = NULL;
  builder->n_terms = 0;
  builder->max_n_terms = 0;
  builder->terms_size = 0;

  builder->path[0] = '\0';
  builder->fd = -1;
  builder->file_buf = NULL;
  builder->file_buf_offset = 0;

  builder->blocks = NULL;
  builder->n_blocks = 0;
  builder->blocks_size = 0;

  grn_ii_builder_buffer_init(ctx, &builder->buf, ii);
  grn_ii_builder_chunk_init(ctx, &builder->chunk);

  builder->df = 0;
  builder->cinfos = NULL;
  builder->n_cinfos = 0;
  builder->cinfos_size = 0;

  return GRN_SUCCESS;
}

/* grn_ii_builder_fin_terms finalizes terms. */
static void
grn_ii_builder_fin_terms(grn_ctx *ctx, grn_ii_builder *builder)
{
  if (builder->terms) {
    uint32_t i;
    for (i = 0; i < builder->max_n_terms; i++) {
      grn_ii_builder_term_fin(ctx, &builder->terms[i]);
    }
    GRN_FREE(builder->terms);

    /* To avoid double finalization. */
    builder->terms = NULL;
  }
}

/* grn_ii_builder_fin finalizes a builder. */
static grn_rc
grn_ii_builder_fin(grn_ctx *ctx, grn_ii_builder *builder)
{
  if (builder->cinfos) {
    GRN_FREE(builder->cinfos);
  }
  grn_ii_builder_chunk_fin(ctx, &builder->chunk);
  grn_ii_builder_buffer_fin(ctx, &builder->buf);
  if (builder->blocks) {
    uint32_t i;
    for (i = 0; i < builder->n_blocks; i++) {
      grn_ii_builder_block_fin(ctx, &builder->blocks[i]);
    }
    GRN_FREE(builder->blocks);
  }
  if (builder->file_buf) {
    GRN_FREE(builder->file_buf);
  }
  if (builder->fd != -1) {
    grn_close(builder->fd);
    if (grn_unlink(builder->path) == 0) {
      GRN_LOG(ctx, GRN_LOG_INFO,
              "[ii][builder][fin] removed path: <%s>",
              builder->path);
    } else {
      ERRNO_ERR("[ii][builder][fin] failed to remove path: <%s>",
                builder->path);
    }
  }
  grn_ii_builder_fin_terms(ctx, builder);
  if (builder->lexicon) {
    grn_obj_close(ctx, builder->lexicon);
  }
  if (builder->srcs) {
    uint32_t i;
    for (i = 0; i < builder->n_srcs; i++) {
      grn_obj_unref(ctx, builder->srcs[i]);
    }
    GRN_FREE(builder->srcs);
  }
  if (builder->src_token_columns) {
    uint32_t i;
    for (i = 0; i < builder->n_srcs; i++) {
      grn_obj_unref(ctx, builder->src_token_columns[i]);
    }
    GRN_FREE(builder->src_token_columns);
  }
  if (builder->src_table) {
    grn_obj_unref(ctx, builder->src_table);
  }
  return GRN_SUCCESS;
}

/*
 * grn_ii_builder_open creates a builder. Note that a builder must be closed by
 * grn_ii_builder_close.
 */
static grn_rc
grn_ii_builder_open(grn_ctx *ctx, grn_ii *ii,
                    const grn_ii_builder_options *options,
                    grn_ii_builder **builder)
{
  grn_rc rc;
  grn_ii_builder *new_builder = GRN_MALLOCN(grn_ii_builder, 1);
  if (!new_builder) {
    return GRN_NO_MEMORY_AVAILABLE;
  }
  if (!options) {
    options = &grn_ii_builder_default_options;
  }
  rc = grn_ii_builder_init(ctx, new_builder, ii, options);
  if (rc != GRN_SUCCESS) {
    GRN_FREE(new_builder);
    return rc;
  }
  *builder = new_builder;
  return GRN_SUCCESS;
}

/* grn_ii_builder_close closes a builder. */
static grn_rc
grn_ii_builder_close(grn_ctx *ctx, grn_ii_builder *builder)
{
  grn_rc rc;
  if (!builder) {
    ERR(GRN_INVALID_ARGUMENT, "builder is null");
    return ctx->rc;
  }
  rc = grn_ii_builder_fin(ctx, builder);
  GRN_FREE(builder);
  return rc;
}

/* grn_ii_builder_create_lexicon creates a block lexicon. */
static grn_rc
grn_ii_builder_create_lexicon(grn_ctx *ctx, grn_ii_builder *builder)
{
  grn_table_flags flags;
  grn_obj *domain = grn_ctx_at(ctx, builder->ii->lexicon->header.domain);
  grn_obj *range = grn_ctx_at(ctx, DB_OBJ(builder->ii->lexicon)->range);
  grn_rc rc;

  rc = grn_table_get_info(ctx, builder->ii->lexicon, &flags, NULL,
                          NULL, NULL, NULL);
  if (rc != GRN_SUCCESS) {
    return rc;
  }
  flags &= ~GRN_OBJ_PERSISTENT;
  builder->lexicon = grn_table_create(ctx, NULL, 0, NULL,
                                      flags, domain, range);
  if (!builder->lexicon) {
    if (ctx->rc == GRN_SUCCESS) {
      ERR(GRN_UNKNOWN_ERROR, "[index] failed to create a block lexicon");
    }
    return ctx->rc;
  }
  {
    grn_obj tokenizer;
    GRN_TEXT_INIT(&tokenizer, 0);
    grn_table_get_default_tokenizer_string(ctx,
                                           builder->ii->lexicon,
                                           &tokenizer);
    if (GRN_TEXT_LEN(&tokenizer) > 0) {
      builder->have_tokenizer = GRN_TRUE;
      rc = grn_obj_set_info(ctx, builder->lexicon,
                            GRN_INFO_DEFAULT_TOKENIZER, &tokenizer);
    }
    GRN_OBJ_FIN(ctx, &tokenizer);
  }
  if (rc == GRN_SUCCESS) {
    grn_obj normalizers;
    GRN_TEXT_INIT(&normalizers, 0);
    grn_table_get_normalizers_string(ctx,
                                     builder->ii->lexicon,
                                     &normalizers);
    if (GRN_TEXT_LEN(&normalizers) > 0) {
      builder->have_normalizers = true;
      rc = grn_obj_set_info(ctx, builder->lexicon,
                            GRN_INFO_NORMALIZERS, &normalizers);
    }
    GRN_OBJ_FIN(ctx, &normalizers);
  }
  if (rc == GRN_SUCCESS) {
    grn_obj token_filters;
    GRN_TEXT_INIT(&token_filters, 0);
    grn_table_get_token_filters_string(ctx,
                                       builder->ii->lexicon,
                                       &token_filters);
    if (GRN_TEXT_LEN(&token_filters) > 0) {
      rc = grn_obj_set_info(ctx,
                            builder->lexicon,
                            GRN_INFO_TOKEN_FILTERS,
                            &token_filters);
    }
    GRN_OBJ_FIN(ctx, &token_filters);
  }
  if (rc != GRN_SUCCESS) {
    return rc;
  }
  if ((flags & GRN_OBJ_TABLE_TYPE_MASK) == GRN_OBJ_TABLE_PAT_KEY) {
    if (builder->options.lexicon_cache_size) {
      rc = grn_pat_cache_enable(ctx, (grn_pat *)builder->lexicon,
                                builder->options.lexicon_cache_size);
      if (rc != GRN_SUCCESS) {
        return rc;
      }
    }
  }
  return GRN_SUCCESS;
}

/*
 * grn_ii_builder_extend_terms extends a buffer for terms in order to make
 * terms[n_terms - 1] available.
 */
static grn_rc
grn_ii_builder_extend_terms(grn_ctx *ctx, grn_ii_builder *builder,
                            uint32_t n_terms)
{
  if (n_terms <= builder->n_terms) {
    return GRN_SUCCESS;
  }

  if (n_terms > builder->max_n_terms) {
    uint32_t i;
    if (n_terms > builder->terms_size) {
      /* Resize builder->terms for new terms. */
      size_t n_bytes;
      uint32_t terms_size = builder->terms_size ? builder->terms_size * 2 : 1;
      grn_ii_builder_term *terms;
      while (terms_size < n_terms) {
        terms_size *= 2;
      }
      n_bytes = terms_size * sizeof(grn_ii_builder_term);
      terms = (grn_ii_builder_term *)GRN_REALLOC(builder->terms, n_bytes);
      if (!terms) {
        ERR(GRN_NO_MEMORY_AVAILABLE,
            "failed to allocate memory for terms: n_bytes = %" GRN_FMT_SIZE,
            n_bytes);
        return ctx->rc;
      }
      builder->terms = terms;
      builder->terms_size = terms_size;
    }
    /* Initialize new terms. */
    for (i = builder->max_n_terms; i < n_terms; i++) {
      grn_ii_builder_term_init(ctx, &builder->terms[i]);
    }
    builder->max_n_terms = n_terms;
  }

  builder->n += n_terms - builder->n_terms;
  builder->n_terms = n_terms;
  return GRN_SUCCESS;
}

/* grn_ii_builder_get_term gets a term associated with tid. */
grn_inline static grn_rc
grn_ii_builder_get_term(grn_ctx *ctx, grn_ii_builder *builder, grn_id tid,
                        grn_ii_builder_term **term)
{
  uint32_t n_terms = tid;
  if (n_terms > builder->n_terms) {
    grn_rc rc = grn_ii_builder_extend_terms(ctx, builder, n_terms);
    if (rc != GRN_SUCCESS) {
      return rc;
    }
  }
  *term = &builder->terms[tid - 1];
  return GRN_SUCCESS;
}

/* grn_ii_builder_flush_file_buf flushes buffered data as a block. */
static grn_rc
grn_ii_builder_flush_file_buf(grn_ctx *ctx, grn_ii_builder *builder)
{
  if (builder->file_buf_offset) {
    ssize_t size = grn_write(builder->fd, builder->file_buf,
                             builder->file_buf_offset);
    if ((uint64_t)size != builder->file_buf_offset) {
      SERR("failed to write data: expected = %u, actual = %" GRN_FMT_INT64D,
           builder->file_buf_offset, (int64_t)size);
    }
    builder->file_buf_offset = 0;
  }
  return GRN_SUCCESS;
}

/* grn_ii_builder_flush_term flushes a term and clears it */
static grn_rc
grn_ii_builder_flush_term(grn_ctx *ctx, grn_ii_builder *builder,
                          grn_ii_builder_term *term)
{
  grn_rc rc;
  uint8_t *term_buf;

  /* Append sentinels. */
  if (term->rid != GRN_ID_NIL) {
    if (builder->ii->header.common->flags & GRN_OBJ_WITH_POSITION) {
      rc = grn_ii_builder_term_append(ctx, term, 0);
    } else {
      rc = grn_ii_builder_term_append(ctx, term, term->pos_or_freq);
    }
    if (rc != GRN_SUCCESS) {
      return rc;
    }
  }
  rc = grn_ii_builder_term_append(ctx, term, 0);
  if (rc != GRN_SUCCESS) {
    return rc;
  }

  {
    /* Put the global term ID. */
    int key_size;
    char key[GRN_TABLE_MAX_KEY_SIZE];
    uint8_t *p;
    uint32_t rest, value;
    grn_rc rc;
    grn_id local_tid = term - builder->terms + 1;
    grn_id global_tid = GRN_ID_NIL;
    key_size = grn_table_get_key(ctx, builder->lexicon, local_tid,
                                 key, GRN_TABLE_MAX_KEY_SIZE);
    if (!key_size) {
      if (ctx->rc == GRN_SUCCESS) {
        ERR(GRN_UNKNOWN_ERROR, "failed to get key: tid = %u", local_tid);
      }
      return ctx->rc;
    }
    /* Don't normalize key. */
    switch (builder->ii->lexicon->header.type) {
    case GRN_TABLE_PAT_KEY :
      GRN_TABLE_LOCK_BEGIN(ctx, builder->ii->lexicon) {
        global_tid = grn_pat_add(ctx,
                                 (grn_pat *)(builder->ii->lexicon),
                                 key,
                                 key_size,
                                 NULL,
                                 NULL);
      } GRN_TABLE_LOCK_END(ctx);
      break;
    case GRN_TABLE_DAT_KEY :
      GRN_TABLE_LOCK_BEGIN(ctx, builder->ii->lexicon) {
        global_tid = grn_dat_add(ctx,
                                 (grn_dat *)(builder->ii->lexicon),
                                 key,
                                 key_size,
                                 NULL,
                                 NULL);
      } GRN_TABLE_LOCK_END(ctx);
      break;
    case GRN_TABLE_HASH_KEY :
      GRN_TABLE_LOCK_BEGIN(ctx, builder->ii->lexicon) {
        global_tid = grn_hash_add(ctx,
                                 (grn_hash *)(builder->ii->lexicon),
                                 key,
                                 key_size,
                                 NULL,
                                 NULL);
      } GRN_TABLE_LOCK_END(ctx);
      break;
    default :
      global_tid = GRN_ID_NIL;
      break;
    }
    if (global_tid == GRN_ID_NIL) {
      if (ctx->rc == GRN_SUCCESS) {
        ERR(GRN_UNKNOWN_ERROR,
            "failed to get global term ID: tid = %u, key = \"%.*s\"",
            local_tid, key_size, key);
      }
      return ctx->rc;
    }

    rest = builder->options.file_buf_size - builder->file_buf_offset;
    if (rest < 10) {
      rc = grn_ii_builder_flush_file_buf(ctx, builder);
      if (rc != GRN_SUCCESS) {
        return rc;
      }
    }
    value = global_tid;
    p = builder->file_buf + builder->file_buf_offset;
    if (value < 1U << 5) {
      p[0] = (uint8_t)value;
      builder->file_buf_offset++;
    } else if (value < 1U << 13) {
      p[0] = (uint8_t)((value & 0x1f) | (1 << 5));
      p[1] = (uint8_t)(value >> 5);
      builder->file_buf_offset += 2;
    } else {
      uint8_t i, n;
      if (value < 1U << 21) {
        n = 3;
      } else if (value < 1U << 29) {
        n = 4;
      } else {
        n = 5;
      }
      p[0] = (uint8_t)(value & 0x1f) | ((n - 1) << 5);
      value >>= 5;
      for (i = 1; i < n; i++) {
        p[i] = (uint8_t)value;
        value >>= 8;
      }
      builder->file_buf_offset += n;
    }
  }

  /* Flush a term buffer. */
  term_buf = grn_ii_builder_term_get_buf(term);
  if (term->offset > builder->options.file_buf_size) {
    ssize_t size;
    rc = grn_ii_builder_flush_file_buf(ctx, builder);
    if (rc != GRN_SUCCESS) {
      return rc;
    }
    size = grn_write(builder->fd, term_buf, term->offset);
    if ((uint64_t)size != term->offset) {
      SERR("failed to write data: expected = %u, actual = %" GRN_FMT_INT64D,
           term->offset, (int64_t)size);
    }
  } else {
    uint32_t rest = builder->options.file_buf_size - builder->file_buf_offset;
    if (term->offset <= rest) {
      grn_memcpy(builder->file_buf + builder->file_buf_offset,
                 term_buf, term->offset);
      builder->file_buf_offset += term->offset;
    } else {
      grn_memcpy(builder->file_buf + builder->file_buf_offset,
                 term_buf, rest);
      builder->file_buf_offset += rest;
      rc = grn_ii_builder_flush_file_buf(ctx, builder);
      if (rc != GRN_SUCCESS) {
        return rc;
      }
      builder->file_buf_offset = term->offset - rest;
      grn_memcpy(builder->file_buf, term_buf + rest, builder->file_buf_offset);
    }
  }
  grn_ii_builder_term_reinit(ctx, term);
  return GRN_SUCCESS;
}

/*
 * grn_ii_builder_create_file creates a temporary file and allocates memory for
 * buffered output.
 */
static grn_rc
grn_ii_builder_create_file(grn_ctx *ctx, grn_ii_builder *builder)
{
  grn_snprintf(builder->path, PATH_MAX, PATH_MAX,
               "%sXXXXXX", grn_io_path(builder->ii->seg));
  builder->fd = grn_mkstemp(builder->path);
  if (builder->fd == -1) {
    SERR("failed to create a temporary file: path = \"%s\"",
         builder->path);
    return ctx->rc;
  }
  builder->file_buf = (uint8_t *)GRN_MALLOC(builder->options.file_buf_size);
  if (!builder->file_buf) {
    ERR(GRN_NO_MEMORY_AVAILABLE,
        "failed to allocate memory for buffered output: size = %u",
        builder->options.file_buf_size);
    return ctx->rc;
  }
  return GRN_SUCCESS;
}

/* grn_ii_builder_register_block registers a block. */
static grn_rc
grn_ii_builder_register_block(grn_ctx *ctx, grn_ii_builder *builder)
{
  grn_ii_builder_block *block;
  uint64_t file_offset = grn_lseek(builder->fd, 0, SEEK_CUR);
  if (file_offset == (uint64_t)-1) {
    SERR("failed to get file offset");
    return ctx->rc;
  }
  if (builder->n_blocks >= builder->blocks_size) {
    size_t n_bytes;
    uint32_t blocks_size = 1;
    grn_ii_builder_block *blocks;
    while (blocks_size <= builder->n_blocks) {
      blocks_size *= 2;
    }
    n_bytes = blocks_size * sizeof(grn_ii_builder_block);
    blocks = (grn_ii_builder_block *)GRN_REALLOC(builder->blocks, n_bytes);
    if (!blocks) {
      ERR(GRN_NO_MEMORY_AVAILABLE,
          "failed to allocate memory for block: n_bytes = %" GRN_FMT_SIZE,
          n_bytes);
      return ctx->rc;
    }
    builder->blocks = blocks;
    builder->blocks_size = blocks_size;
  }
  block = &builder->blocks[builder->n_blocks];
  grn_ii_builder_block_init(ctx, block);
  if (!builder->n_blocks) {
    block->offset = 0;
  } else {
    grn_ii_builder_block *prev_block = &builder->blocks[builder->n_blocks - 1];
    block->offset = prev_block->offset + prev_block->rest;
  }
  block->rest = (uint32_t)(file_offset - block->offset);
  builder->n_blocks++;
  return GRN_SUCCESS;
}

/* grn_ii_builder_flush_block flushes a block to a temporary file. */
static grn_rc
grn_ii_builder_flush_block(grn_ctx *ctx, grn_ii_builder *builder)
{
  grn_rc rc;
  grn_table_cursor *cursor;

  if (!builder->n) {
    /* Do nothing if there are no output data. */
    return GRN_SUCCESS;
  }
  if (builder->fd == -1) {
    rc = grn_ii_builder_create_file(ctx, builder);
    if (rc != GRN_SUCCESS) {
      return rc;
    }
  }

  /* Flush terms into a temporary file. */
  cursor = grn_table_cursor_open(ctx, builder->lexicon,
                                 NULL, 0, NULL, 0, 0, -1, GRN_CURSOR_BY_KEY);
  for (;;) {
    grn_id tid = grn_table_cursor_next(ctx, cursor);
    if (tid == GRN_ID_NIL) {
      break;
    }
    rc = grn_ii_builder_flush_term(ctx, builder, &builder->terms[tid - 1]);
    if (rc != GRN_SUCCESS) {
      return rc;
    }
  }
  grn_table_cursor_close(ctx, cursor);
  rc = grn_ii_builder_flush_file_buf(ctx, builder);
  if (rc != GRN_SUCCESS) {
    return rc;
  }

  /* Register a block and clear the current data. */
  rc = grn_ii_builder_register_block(ctx, builder);
  if (rc != GRN_SUCCESS) {
    return rc;
  }
  rc = grn_table_truncate(ctx, builder->lexicon);
  if (rc != GRN_SUCCESS) {
    return rc;
  }
  builder->rid = GRN_ID_NIL;
  builder->n_terms = 0;
  builder->n = 0;
  return GRN_SUCCESS;
}

/* grn_ii_builder_append_token appends a token. */
static grn_rc
grn_ii_builder_append_token(grn_ctx *ctx, grn_ii_builder *builder,
                            grn_id rid, uint32_t sid, uint32_t weight,
                            grn_id tid, uint32_t pos)
{
  grn_rc rc;
  uint32_t ii_flags = builder->ii->header.common->flags;
  grn_ii_builder_term *term;
  rc = grn_ii_builder_get_term(ctx, builder, tid, &term);
  if (rc != GRN_SUCCESS) {
    return rc;
  }
  if (rid != term->rid || sid != term->sid) {
    uint64_t rsid;
    if (term->rid != GRN_ID_NIL) {
      if (ii_flags & GRN_OBJ_WITH_POSITION) {
        /* Append the end of positions. */
        rc = grn_ii_builder_term_append(ctx, term, 0);
        if (rc != GRN_SUCCESS) {
          return rc;
        }
        builder->n++;
      } else {
        /* Append a frequency if positions are not available. */
        rc = grn_ii_builder_term_append(ctx, term, term->pos_or_freq);
        if (rc != GRN_SUCCESS) {
          return rc;
        }
        builder->n++;
      }
    }
    rsid = ((uint64_t)(rid - term->rid) << builder->sid_bits) | (sid - 1);
    rc = grn_ii_builder_term_append(ctx, term, rsid);
    if (rc != GRN_SUCCESS) {
      return rc;
    }
    builder->n++;
    if (ii_flags & GRN_OBJ_WITH_WEIGHT) {
      rc = grn_ii_builder_term_append(ctx, term, weight);
      if (rc != GRN_SUCCESS) {
        return rc;
      }
      builder->n++;
    }
    term->rid = rid;
    term->sid = sid;
    term->pos_or_freq = 0;
  }
  if (ii_flags & GRN_OBJ_WITH_POSITION) {
    rc = grn_ii_builder_term_append(ctx, term, pos - term->pos_or_freq);
    if (rc != GRN_SUCCESS) {
      return rc;
    }
    builder->n++;
    term->pos_or_freq = pos;
  } else {
    term->pos_or_freq++;
  }
  return GRN_SUCCESS;
}

static void
grn_ii_builder_start_value(grn_ctx *ctx,
                           grn_ii_builder *builder,
                           grn_id rid,
                           uint32_t sid)
{
  if (rid != builder->rid) {
    builder->rid = rid;
    builder->sid = sid;
    builder->pos = 1;
  } else if (sid != builder->sid) {
    builder->sid = sid;
    builder->pos = 1;
  } else {
    /* Insert a space between values. */
    builder->pos++;
  }
}

static grn_rc
grn_ii_builder_append_tokens(grn_ctx *ctx,
                             grn_ii_builder *builder,
                             grn_id rid,
                             uint32_t sid,
                             grn_obj *tokens)
{
  grn_ii_builder_start_value(ctx, builder, rid, sid);
  grn_obj *src_lexicon = builder->ii->lexicon;
  size_t n_tokens = grn_uvector_size(ctx, tokens);
  size_t i;
  for (i = 0; i < n_tokens; i++) {
    float weight;
    grn_id tid;
    grn_id src_tid = grn_uvector_get_element_record(ctx, tokens, i, &weight);
    uint32_t token_value_size;
    const char *token_value = _grn_table_key(ctx,
                                             src_lexicon,
                                             src_tid,
                                             &token_value_size);

    switch (builder->lexicon->header.type) {
    case GRN_TABLE_PAT_KEY :
      tid = grn_pat_add(ctx, (grn_pat *)builder->lexicon,
                        token_value, token_value_size, NULL, NULL);
      break;
    case GRN_TABLE_DAT_KEY :
      tid = grn_dat_add(ctx, (grn_dat *)builder->lexicon,
                        token_value, token_value_size, NULL, NULL);
      break;
    case GRN_TABLE_HASH_KEY :
      tid = grn_hash_add(ctx, (grn_hash *)builder->lexicon,
                         token_value, token_value_size, NULL, NULL);
      break;
    default :
      /* This case must not be happen. */
      tid = GRN_ID_NIL;
      break;
    }

    if (tid == GRN_ID_NIL) {
      /* TODO: Token value may not be a string. */
      ERR(GRN_INVALID_ARGUMENT,
          "[ii][builder][append-tokens] failed to add a token: <%.*s>",
          (int)token_value_size,
          token_value);
      return ctx->rc;
    }
    uint32_t pos = builder->pos + i;
    grn_rc rc = grn_ii_builder_append_token(ctx,
                                            builder,
                                            rid,
                                            sid,
                                            weight,
                                            tid,
                                            pos);
    if (rc != GRN_SUCCESS) {
      return rc;
    }
  }
  return GRN_SUCCESS;
}

/*
 * grn_ii_builder_append_value appends a value. Note that values must be
 * appended in ascending rid and sid order.
 */
static grn_rc
grn_ii_builder_append_value(grn_ctx *ctx, grn_ii_builder *builder,
                            grn_id rid, uint32_t sid, uint32_t weight,
                            const char *value, uint32_t value_size)
{
  uint32_t pos = 0;
  grn_token_cursor *cursor;
  grn_ii_builder_start_value(ctx, builder, rid, sid);
  if (value_size) {
    if (!builder->have_tokenizer && !builder->have_normalizers) {
      grn_id tid;
      switch (builder->lexicon->header.type) {
      case GRN_TABLE_PAT_KEY :
        tid = grn_pat_add(ctx, (grn_pat *)builder->lexicon,
                          value, value_size, NULL, NULL);
        break;
      case GRN_TABLE_DAT_KEY :
        tid = grn_dat_add(ctx, (grn_dat *)builder->lexicon,
                          value, value_size, NULL, NULL);
        break;
      case GRN_TABLE_HASH_KEY :
        tid = grn_hash_add(ctx, (grn_hash *)builder->lexicon,
                           value, value_size, NULL, NULL);
        break;
      case GRN_TABLE_NO_KEY :
        tid = *(grn_id *)value;
        break;
      default :
        tid = GRN_ID_NIL;
        break;
      }
      if (tid != GRN_ID_NIL) {
        grn_rc rc;
        pos = builder->pos;
        rc = grn_ii_builder_append_token(ctx, builder, rid, sid,
                                         weight, tid, pos);
        if (rc != GRN_SUCCESS) {
          return rc;
        }
      }
    } else {
      cursor = grn_token_cursor_open(ctx, builder->lexicon, value, value_size,
                                     GRN_TOKEN_ADD, 0);
      if (!cursor) {
        if (ctx->rc == GRN_SUCCESS) {
          ERR(GRN_UNKNOWN_ERROR,
              "grn_token_cursor_open failed: value = <%.*s>",
              value_size, value);
        }
        return ctx->rc;
      }
      while (cursor->status == GRN_TOKEN_CURSOR_DOING) {
        grn_id tid = grn_token_cursor_next(ctx, cursor);
        if (tid != GRN_ID_NIL) {
          grn_rc rc;
          pos = builder->pos + cursor->pos;
          rc = grn_ii_builder_append_token(ctx, builder, rid, sid,
                                           weight, tid, pos);
          if (rc != GRN_SUCCESS) {
            break;
          }
        }
      }
      grn_token_cursor_close(ctx, cursor);
    }
  }
  builder->pos = pos + 1;
  return ctx->rc;
}

/* grn_ii_builder_append_obj appends a BULK, UVECTOR or VECTOR object. */
static grn_rc
grn_ii_builder_append_obj(grn_ctx *ctx, grn_ii_builder *builder,
                          grn_id rid, uint32_t sid, grn_obj *obj)
{
  switch (obj->header.type) {
  case GRN_BULK :
    return grn_ii_builder_append_value(ctx, builder, rid, sid, 0,
                                       GRN_TEXT_VALUE(obj), GRN_TEXT_LEN(obj));
  case GRN_UVECTOR :
    {
      const char *p = GRN_BULK_HEAD(obj);
      uint32_t i, n_values = grn_uvector_size(ctx, obj);
      uint32_t value_size = grn_uvector_element_size(ctx, obj);
      for (i = 0; i < n_values; i++) {
        grn_rc rc = grn_ii_builder_append_value(ctx, builder, rid, sid, 0,
                                                p, value_size);
        if (rc != GRN_SUCCESS) {
          return rc;
        }
        p += value_size;
      }
    }
    return GRN_SUCCESS;
  case GRN_VECTOR :
    if (obj->u.v.body) {
      /*
       * Note that the following sections and n_sections don't correspond to
       * source columns.
       */
      int i, n_secs = obj->u.v.n_sections;
      grn_section *secs = obj->u.v.sections;
      const char *head = GRN_BULK_HEAD(obj->u.v.body);
      for (i = 0; i < n_secs; i++) {
        grn_rc rc;
        grn_section *sec = &secs[i];
        if (sec->length == 0) {
          continue;
        }
        if ((builder->ii->header.common->flags & GRN_OBJ_WITH_SECTION) &&
            builder->have_tokenizer) {
          sid = i + 1;
        }
        rc = grn_ii_builder_append_value(ctx, builder, rid, sid, sec->weight,
                                         head + sec->offset, sec->length);
        if (rc != GRN_SUCCESS) {
          return rc;
        }
      }
    }
    return GRN_SUCCESS;
  default :
    ERR(GRN_INVALID_ARGUMENT, "[index] invalid object assigned as value");
    return ctx->rc;
  }
}

/*
 * grn_ii_builder_append_srcs reads values from source columns and appends the
 * values.
 */
static grn_rc
grn_ii_builder_append_srcs(grn_ctx *ctx, grn_ii_builder *builder)
{
  size_t i;
  grn_rc rc = GRN_SUCCESS;
  grn_obj *objs;
  grn_table_cursor *cursor;

  /* Allocate memory for objects to store source values. */
  objs = GRN_MALLOCN(grn_obj, builder->n_srcs);
  if (!objs) {
    ERR(GRN_NO_MEMORY_AVAILABLE,
        "failed to allocate memory for objs: n_srcs = %u", builder->n_srcs);
    return ctx->rc;
  }

  /* Create a cursor to get records in the ID order. */
  cursor = grn_table_cursor_open(ctx, builder->src_table, NULL, 0, NULL, 0,
                                 0, -1, GRN_CURSOR_BY_ID);
  if (!cursor) {
    if (ctx->rc == GRN_SUCCESS) {
      ERR(GRN_OBJECT_CORRUPT, "[index] failed to open table cursor");
    }
    GRN_FREE(objs);
    return ctx->rc;
  }

  /* Read source values and append it. */
  for (i = 0; i < builder->n_srcs; i++) {
    GRN_TEXT_INIT(&objs[i], 0);
  }
  while (rc == GRN_SUCCESS) {
    grn_id rid = grn_table_cursor_next(ctx, cursor);
    if (rid == GRN_ID_NIL) {
      break;
    }
    for (i = 0; i < builder->n_srcs; i++) {
      grn_obj *obj = &objs[i];
      grn_obj *src = builder->srcs[i];
      grn_obj *token_column = builder->src_token_columns[i];
      if (token_column) {
        rc = grn_obj_reinit_for(ctx, obj, token_column);
        if (rc == GRN_SUCCESS) {
          if (!grn_obj_get_value(ctx, token_column, rid, obj)) {
            if (ctx->rc == GRN_SUCCESS) {
              ERR(GRN_UNKNOWN_ERROR, "failed to get tokens: rid = %u", rid);
            }
            rc = ctx->rc;
          }
          if (rc == GRN_SUCCESS) {
            uint32_t sid = (uint32_t)(i + 1);
            rc = grn_ii_builder_append_tokens(ctx, builder, rid, sid, obj);
          }
        }
      } else {
        rc = grn_obj_reinit_for(ctx, obj, src);
        if (rc == GRN_SUCCESS) {
          if (GRN_OBJ_TABLEP(src)) {
            int len = grn_table_get_key2(ctx, src, rid, obj);
            if (len <= 0) {
              if (ctx->rc == GRN_SUCCESS) {
                ERR(GRN_UNKNOWN_ERROR, "failed to get key: rid = %u, len = %d",
                    rid, len);
              }
              rc = ctx->rc;
            }
          } else {
            if (!grn_obj_get_value(ctx, src, rid, obj)) {
              if (ctx->rc == GRN_SUCCESS) {
                ERR(GRN_UNKNOWN_ERROR, "failed to get value: rid = %u", rid);
              }
              rc = ctx->rc;
            }
          }
          if (rc == GRN_SUCCESS) {
            uint32_t sid = (uint32_t)(i + 1);
            rc = grn_ii_builder_append_obj(ctx, builder, rid, sid, obj);
          }
        }
      }
    }
    if (rc == GRN_SUCCESS && builder->n >= builder->options.block_threshold) {
      rc = grn_ii_builder_flush_block(ctx, builder);
    }
  }
  if (rc == GRN_SUCCESS) {
    rc = grn_ii_builder_flush_block(ctx, builder);
  }
  for (i = 0; i < builder->n_srcs; i++) {
    GRN_OBJ_FIN(ctx, &objs[i]);
  }
  grn_table_cursor_close(ctx, cursor);
  GRN_FREE(objs);
  return rc;
}

/* grn_ii_builder_set_src_table sets a source table. */
static grn_rc
grn_ii_builder_set_src_table(grn_ctx *ctx, grn_ii_builder *builder)
{
  builder->src_table = grn_ctx_at(ctx, DB_OBJ(builder->ii)->range);
  if (!builder->src_table) {
    if (ctx->rc == GRN_SUCCESS) {
      ERR(GRN_INVALID_ARGUMENT, "source table is null: range = %d",
          DB_OBJ(builder->ii)->range);
    }
    return ctx->rc;
  }
  return GRN_SUCCESS;
}

/* grn_ii_builder_set_sid_bits calculates sid_bits and sid_mask. */
static grn_rc
grn_ii_builder_set_sid_bits(grn_ctx *ctx, grn_ii_builder *builder)
{
  /* Calculate the number of bits required to represent a section ID. */
  if (builder->n_srcs == 1 && builder->have_tokenizer &&
      (builder->srcs[0]->header.flags & GRN_OBJ_COLUMN_VECTOR) != 0) {
    /* If the source column is a vector column and the index has a tokenizer, */
    /* the maximum sid equals to the maximum number of elements. */
    size_t max_elems = 0;
    grn_table_cursor *cursor;
    grn_obj obj;
    cursor = grn_table_cursor_open(ctx, builder->src_table, NULL, 0, NULL, 0,
                                    0, -1, GRN_CURSOR_BY_ID);
    if (!cursor) {
      if (ctx->rc == GRN_SUCCESS) {
        ERR(GRN_OBJECT_CORRUPT, "[index] failed to open table cursor");
      }
      return ctx->rc;
    }
    GRN_TEXT_INIT(&obj, 0);
    for (;;) {
      grn_id rid = grn_table_cursor_next(ctx, cursor);
      if (rid == GRN_ID_NIL) {
        break;
      }
      GRN_BULK_REWIND(&obj);
      if (!grn_obj_get_value(ctx, builder->srcs[0], rid, &obj)) {
        continue;
      }
      if (obj.u.v.n_sections > max_elems) {
        max_elems = obj.u.v.n_sections;
      }
    }
    GRN_OBJ_FIN(ctx, &obj);
    grn_table_cursor_close(ctx, cursor);
    while (((uint32_t)1 << builder->sid_bits) < max_elems) {
      builder->sid_bits++;
    }
  }
  if (builder->sid_bits == 0) {
    while (((uint32_t)1 << builder->sid_bits) < builder->n_srcs) {
      builder->sid_bits++;
    }
  }
  builder->sid_mask = ((uint64_t)1 << builder->sid_bits) - 1;
  return GRN_SUCCESS;
}

/* grn_ii_builder_set_srcs sets source columns. */
static grn_rc
grn_ii_builder_set_srcs(grn_ctx *ctx, grn_ii_builder *builder)
{
  size_t i;
  grn_id *source;
  builder->n_srcs = builder->ii->obj.source_size / sizeof(grn_id);
  source = (grn_id *)builder->ii->obj.source;
  if (!source || !builder->n_srcs) {
    ERR(GRN_INVALID_ARGUMENT,
        "source is not available: source = %p, source_size = %u",
        builder->ii->obj.source, builder->ii->obj.source_size);
    return ctx->rc;
  }
  builder->srcs = GRN_MALLOCN(grn_obj *, builder->n_srcs);
  if (!builder->srcs) {
    return GRN_NO_MEMORY_AVAILABLE;
  }
  for (i = 0; i < builder->n_srcs; i++) {
    builder->srcs[i] = grn_ctx_at(ctx, source[i]);
    if (!builder->srcs[i]) {
      if (ctx->rc == GRN_SUCCESS) {
        ERR(GRN_OBJECT_CORRUPT, "source not found: id = %d", source[i]);
      }
      return ctx->rc;
    }
  }
  builder->src_token_columns = GRN_MALLOCN(grn_obj *, builder->n_srcs);
  if (!builder->src_token_columns) {
    return GRN_NO_MEMORY_AVAILABLE;
  }
  {
    grn_obj token_columns;
    GRN_PTR_INIT(&token_columns, GRN_OBJ_VECTOR, GRN_ID_NIL);
    for (i = 0; i < builder->n_srcs; i++) {
      builder->src_token_columns[i] = NULL;
      grn_obj *src = builder->srcs[i];
      grn_column_get_all_token_columns(ctx, src, &token_columns);
      size_t n_token_columns = GRN_PTR_VECTOR_SIZE(&token_columns);
      size_t j;
      for (j = 0; j < n_token_columns; j++) {
        grn_obj *token_column = GRN_PTR_VALUE_AT(&token_columns, j);
        if (!builder->src_token_columns[i] &&
            DB_OBJ(token_column)->range == DB_OBJ(builder->ii->lexicon)->id) {
          builder->src_token_columns[i] = token_column;
        } else {
          grn_obj_unref(ctx, token_column);
        }
      }
      GRN_BULK_REWIND(&token_columns);
    }
    GRN_OBJ_FIN(ctx, &token_columns);
  }
  return grn_ii_builder_set_sid_bits(ctx, builder);
}

/* grn_ii_builder_append_source appends values in source columns. */
static grn_rc
grn_ii_builder_append_source(grn_ctx *ctx, grn_ii_builder *builder)
{
  grn_rc rc = grn_ii_builder_set_src_table(ctx, builder);
  if (rc != GRN_SUCCESS) {
    return rc;
  }
  if (grn_table_size(ctx, builder->src_table) == 0) {
    /* Nothing to do because there are no values. */
    return ctx->rc;
  }
  /* Create a block lexicon. */
  rc = grn_ii_builder_create_lexicon(ctx, builder);
  if (rc != GRN_SUCCESS) {
    return rc;
  }
  rc = grn_ii_builder_set_srcs(ctx, builder);
  if (rc != GRN_SUCCESS) {
    return rc;
  }
  rc = grn_ii_builder_append_srcs(ctx, builder);
  if (rc != GRN_SUCCESS) {
    return rc;
  }
  grn_ii_builder_fin_terms(ctx, builder);
  return GRN_SUCCESS;
}

/*
 * grn_ii_builder_fill_block reads the next data from a temporary file and fill
 * a block buffer.
 */
static grn_rc
grn_ii_builder_fill_block(grn_ctx *ctx, grn_ii_builder *builder,
                          uint32_t block_id)
{
  ssize_t size;
  uint32_t buf_rest;
  uint64_t file_offset;
  grn_ii_builder_block *block = &builder->blocks[block_id];
  if (!block->rest) {
    return GRN_END_OF_DATA;
  }
  if (!block->buf) {
    block->buf = (uint8_t *)GRN_MALLOC(builder->options.block_buf_size);
    if (!block->buf) {
      ERR(GRN_NO_MEMORY_AVAILABLE,
          "failed to allocate memory for buffered input: size = %u",
          builder->options.block_buf_size);
      return ctx->rc;
    }
  }

  /* Move the remaining data to the head. */
  buf_rest = block->end - block->cur;
  if (buf_rest) {
    grn_memmove(block->buf, block->cur, buf_rest);
  }
  block->cur = block->buf;
  block->end = block->buf + buf_rest;

  /* Read the next data. */
  file_offset = grn_lseek(builder->fd, block->offset, SEEK_SET);
  if (file_offset != block->offset) {
    SERR("failed to seek file: expected = %" GRN_FMT_INT64U
         ", actual = %" GRN_FMT_INT64D,
         block->offset, file_offset);
    return ctx->rc;
  }
  buf_rest = builder->options.block_buf_size - buf_rest;
  if (block->rest < buf_rest) {
    buf_rest = block->rest;
  }
  size = grn_read(builder->fd, block->end, buf_rest);
  if (size <= 0) {
    SERR("failed to read data: expected = %u, actual = %" GRN_FMT_INT64D,
         buf_rest, (int64_t)size);
    return ctx->rc;
  }
  block->offset += size;
  block->rest -= size;
  block->end += size;
  return GRN_SUCCESS;
}

/* grn_ii_builder_read_from_block reads the next value from a block. */
static grn_rc
grn_ii_builder_read_from_block(grn_ctx *ctx, grn_ii_builder *builder,
                               uint32_t block_id, uint64_t *value)
{
  grn_ii_builder_block *block = &builder->blocks[block_id];
  grn_rc rc = grn_ii_builder_block_next(ctx, block, value);
  if (rc == GRN_SUCCESS) {
    return GRN_SUCCESS;
  } else if (rc == GRN_END_OF_DATA) {
    rc = grn_ii_builder_fill_block(ctx, builder, block_id);
    if (rc != GRN_SUCCESS) {
      return rc;
    }
    return grn_ii_builder_block_next(ctx, block, value);
  }
  return rc;
}

/* grn_ii_builder_pack_chunk tries to pack a chunk. */
static grn_rc
grn_ii_builder_pack_chunk(grn_ctx *ctx, grn_ii_builder *builder,
                          grn_bool *packed)
{
  grn_id rid;
  uint32_t sid, pos, *a;
  grn_ii_builder_chunk *chunk = &builder->chunk;
  *packed = GRN_FALSE;
  if (chunk->offset != 1) { /* df != 1 */
    return GRN_SUCCESS;
  }
  if (chunk->weight_buf && chunk->weight_buf[0]) { /* weight != 0 */
    return GRN_SUCCESS;
  }
  if (chunk->freq_buf[0] != 0) { /* freq != 1 */
    return GRN_SUCCESS;
  }
  rid = chunk->rid_buf[0];
  if (chunk->sid_buf) {
    if (rid >= 0x100000) {
      return GRN_SUCCESS;
    }
    sid = chunk->sid_buf[0] + 1;
    if (sid >= 0x800) {
      return GRN_SUCCESS;
    }
    a = array_get(ctx, builder->ii, chunk->tid);
    if (!a) {
      grn_obj token;
      GRN_DEFINE_NAME(builder->ii);
      GRN_TEXT_INIT(&token, 0);
      grn_ii_get_term(ctx, builder->ii, chunk->tid, &token);
      MERR("[ii][builder][chunk][pack] failed to allocate an array: "
           "<%.*s>: "
           "<%.*s>(%u): "
           "(%u:%u)",
           name_size, name,
           (int)GRN_TEXT_LEN(&token), GRN_TEXT_VALUE(&token),
           chunk->tid,
           rid, sid);
      GRN_OBJ_FIN(ctx, &token);
      return ctx->rc;
    }
    a[0] = POS_EMBED_RID_SID(rid, sid);
  } else {
    a = array_get(ctx, builder->ii, chunk->tid);
    if (!a) {
      grn_obj token;
      GRN_DEFINE_NAME(builder->ii);
      GRN_TEXT_INIT(&token, 0);
      grn_ii_get_term(ctx, builder->ii, chunk->tid, &token);
      MERR("[ii][builder][chunk][pack] failed to allocate an array: "
           "<%.*s>: "
           "<%.*s>(%u): "
           "(%u)",
           name_size, name,
           (int)GRN_TEXT_LEN(&token), GRN_TEXT_VALUE(&token),
           chunk->tid,
           rid);
      GRN_OBJ_FIN(ctx, &token);
      return ctx->rc;
    }
    a[0] = POS_EMBED_RID(rid);
  }
  pos = 0;
  if (chunk->pos_buf) {
    pos = chunk->pos_buf[0];
  }
  a[1] = pos;
  array_unref(ctx, builder->ii, chunk->tid);
  *packed = GRN_TRUE;

  grn_ii_builder_chunk_clear(ctx, chunk);
  return GRN_SUCCESS;
}

/* grn_ii_builder_get_cinfo returns a new cinfo. */
static grn_rc
grn_ii_builder_get_cinfo(grn_ctx *ctx, grn_ii_builder *builder,
                         chunk_info **cinfo)
{
  if (builder->n_cinfos == builder->cinfos_size) {
    uint32_t size = builder->cinfos_size ? (builder->cinfos_size * 2) : 1;
    size_t n_bytes = size * sizeof(chunk_info);
    chunk_info *cinfos = (chunk_info *)GRN_REALLOC(builder->cinfos, n_bytes);
    if (!cinfos) {
      ERR(GRN_NO_MEMORY_AVAILABLE,
          "failed to allocate memory for cinfos: n_bytes = %" GRN_FMT_SIZE,
          n_bytes);
      return ctx->rc;
    }
    builder->cinfos = cinfos;
    builder->cinfos_size = size;
  }
  *cinfo = &builder->cinfos[builder->n_cinfos++];
  return GRN_SUCCESS;
}

/* grn_ii_builder_flush_chunk flushes a chunk. */
static grn_rc
grn_ii_builder_flush_chunk(grn_ctx *ctx, grn_ii_builder *builder)
{
  grn_rc rc;
  chunk_info *cinfo = NULL;
  grn_ii_builder_chunk *chunk = &builder->chunk;
  void *seg;
  uint8_t *in;
  uint32_t in_size, chunk_id, seg_id, seg_offset, seg_rest;

  rc = grn_ii_builder_chunk_encode(ctx, chunk, NULL, 0);
  if (rc != GRN_SUCCESS) {
    return rc;
  }
  in = chunk->enc_buf;
  in_size = chunk->enc_offset;

  rc = chunk_new(ctx, builder->ii, &chunk_id, chunk->enc_offset);
  if (rc != GRN_SUCCESS) {
    return rc;
  }

  /* Copy to the first segment. */
  seg_id = chunk_id >> GRN_II_N_CHUNK_VARIATION;
  seg_offset = (chunk_id & ((1 << GRN_II_N_CHUNK_VARIATION) - 1)) <<
               GRN_II_W_LEAST_CHUNK;
  seg = grn_io_seg_ref(ctx, builder->ii->chunk, seg_id);
  if (!seg) {
    if (ctx->rc == GRN_SUCCESS) {
      ERR(GRN_UNKNOWN_ERROR,
          "failed access chunk segment: chunk_id = %u, seg_id = %u",
          chunk_id, seg_id);
    }
    return ctx->rc;
  }
  seg_rest = S_CHUNK - seg_offset;
  if (in_size <= seg_rest) {
    grn_memcpy((uint8_t *)seg + seg_offset, in, in_size);
    in_size = 0;
  } else {
    grn_memcpy((uint8_t *)seg + seg_offset, in, seg_rest);
    in += seg_rest;
    in_size -= seg_rest;
  }
  grn_io_seg_unref(ctx, builder->ii->chunk, seg_id);

  /* Copy to the next segments. */
  while (in_size) {
    seg_id++;
    seg = grn_io_seg_ref(ctx, builder->ii->chunk, seg_id);
    if (!seg) {
      if (ctx->rc == GRN_SUCCESS) {
        ERR(GRN_UNKNOWN_ERROR,
            "failed access chunk segment: chunk_id = %u, seg_id = %u",
            chunk_id, seg_id);
      }
      return ctx->rc;
    }
    if (in_size <= S_CHUNK) {
      grn_memcpy(seg, in, in_size);
      in_size = 0;
    } else {
      grn_memcpy(seg, in, S_CHUNK);
      in += S_CHUNK;
      in_size -= S_CHUNK;
    }
    grn_io_seg_unref(ctx, builder->ii->chunk, seg_id);
  }

  /* Append a cinfo. */
  rc = grn_ii_builder_get_cinfo(ctx, builder, &cinfo);
  if (rc != GRN_SUCCESS) {
    return rc;
  }
  cinfo->segno = chunk_id;
  cinfo->size = chunk->enc_offset;
  cinfo->dgap = chunk->rid_gap;

  builder->buf.ii->header.common->total_chunk_size += chunk->enc_offset;
  grn_ii_builder_chunk_clear(ctx, chunk);
  return GRN_SUCCESS;
}

/* grn_ii_builder_read_to_chunk read values from a block to a chunk. */
static grn_rc
grn_ii_builder_read_to_chunk(grn_ctx *ctx, grn_ii_builder *builder,
                             uint32_t block_id)
{
  grn_rc rc;
  uint64_t value;
  uint32_t rid = GRN_ID_NIL, last_sid = 0;
  uint32_t ii_flags = builder->ii->header.common->flags;
  grn_ii_builder_chunk *chunk = &builder->chunk;

  for (;;) {
    uint32_t gap, freq;
    uint64_t value;
    rc = grn_ii_builder_read_from_block(ctx, builder, block_id, &value);
    if (rc != GRN_SUCCESS) {
      return rc;
    }
    if (!value) {
      break;
    }
    if (chunk->offset == chunk->size) {
      rc = grn_ii_builder_chunk_extend_bufs(ctx, chunk, ii_flags);
      if (rc != GRN_SUCCESS) {
        return rc;
      }
    }

    /* Read record ID. */
    gap = value >> builder->sid_bits; /* In-block gap */
    if (gap) {
      if (chunk->n >= builder->options.chunk_threshold) {
        const double threshold_scale = 1 + log(builder->df + 1);
        const double threshold =
          builder->options.chunk_threshold * threshold_scale;
        if (chunk->n >= threshold) {
          if (grn_logger_pass(ctx, GRN_LOG_DEBUG)) {
            grn_obj token;
            GRN_DEFINE_NAME(builder->ii);
            GRN_TEXT_INIT(&token, 0);
            grn_ii_get_term(ctx, builder->ii, chunk->tid, &token);
            GRN_LOG(ctx, GRN_LOG_DEBUG,
                    "[ii][builder][read-to-chunk] flush"
                    "<%.*s>: "
                    "<%.*s>(%u): "
                    "n=<%u> "
                    "df=<%u> "
                    "threshold=<%.1f>",
                    name_size, name,
                    (int)GRN_TEXT_LEN(&token), GRN_TEXT_VALUE(&token),
                    chunk->tid,
                    chunk->n,
                    builder->df,
                    threshold);
            GRN_OBJ_FIN(ctx, &token);
          }
          rc = grn_ii_builder_flush_chunk(ctx, builder);
          if (rc != GRN_SUCCESS) {
            return rc;
          }
        }
      }
      last_sid = 0;
    }
    rid += gap;
    gap = rid - chunk->rid; /* Global gap */
    chunk->rid_buf[chunk->offset] = chunk->offset ? gap : rid;
    chunk->n++;
    chunk->rid = rid;
    chunk->rid_gap += gap;
    builder->df++;

    /* Read section ID. */
    if (ii_flags & GRN_OBJ_WITH_SECTION) {
      uint32_t sid = (value & builder->sid_mask) + 1;
      chunk->sid_buf[chunk->offset] = sid - last_sid - 1;
      chunk->n++;
      last_sid = sid;
    }

    /* Read weight. */
    if (ii_flags & GRN_OBJ_WITH_WEIGHT) {
      uint32_t weight;
      rc = grn_ii_builder_read_from_block(ctx, builder, block_id, &value);
      if (rc != GRN_SUCCESS) {
        return rc;
      }
      weight = value;
      chunk->weight_buf[chunk->offset] = weight;
      chunk->n++;
    }

    /* Read positions or a frequency. */
    if (ii_flags & GRN_OBJ_WITH_POSITION) {
      uint32_t pos = -1;
      freq = 0;
      for (;;) {
        rc = grn_ii_builder_read_from_block(ctx, builder, block_id, &value);
        if (rc != GRN_SUCCESS) {
          return rc;
        }
        if (!value) {
          break;
        }
        if (builder->chunk.pos_offset == builder->chunk.pos_size) {
          rc = grn_ii_builder_chunk_extend_pos_buf(ctx, chunk);
          if (rc != GRN_SUCCESS) {
            return rc;
          }
        }
        if (pos == (uint32_t)-1) {
          chunk->pos_buf[chunk->pos_offset] = value - 1;
          chunk->pos_sum += value - 1;
        } else {
          chunk->pos_buf[chunk->pos_offset] = value;
          chunk->pos_sum += value;
        }
        chunk->n++;
        pos += value;
        chunk->pos_offset++;
        freq++;
      }
    } else {
      rc = grn_ii_builder_read_from_block(ctx, builder, block_id, &value);
      if (rc != GRN_SUCCESS) {
        return rc;
      }
      freq = value;
    }
    chunk->freq_buf[chunk->offset] = freq - 1;
    chunk->n++;
    chunk->offset++;
  }
  rc = grn_ii_builder_read_from_block(ctx, builder, block_id, &value);
  if (rc == GRN_SUCCESS) {
    builder->blocks[block_id].tid = value;
  } else if (rc == GRN_END_OF_DATA) {
    builder->blocks[block_id].tid = GRN_ID_NIL;
  } else {
    return rc;
  }
  return GRN_SUCCESS;
}

/* grn_ii_builder_register_chunks registers chunks. */
static grn_rc
grn_ii_builder_register_chunks(grn_ctx *ctx, grn_ii_builder *builder)
{
  grn_rc rc;
  uint32_t buf_tid, *a;
  buffer_term *buf_term;

  rc = grn_ii_builder_chunk_encode(ctx, &builder->chunk, builder->cinfos,
                                   builder->n_cinfos);
  if (rc != GRN_SUCCESS) {
    return rc;
  }

  if (!grn_ii_builder_buffer_is_assigned(ctx, &builder->buf)) {
    rc = grn_ii_builder_buffer_assign(ctx, &builder->buf,
                                      builder->chunk.enc_offset);
    if (rc != GRN_SUCCESS) {
      return rc;
    }
  }
  buf_tid = builder->buf.buf->header.nterms;
  if (buf_tid >= builder->options.buffer_max_n_terms ||
      builder->buf.chunk_size - builder->buf.chunk_offset <
      builder->chunk.enc_offset) {
    rc = grn_ii_builder_buffer_flush(ctx, &builder->buf);
    if (rc != GRN_SUCCESS) {
      return rc;
    }
    rc = grn_ii_builder_buffer_assign(ctx, &builder->buf,
                                      builder->chunk.enc_offset);
    if (rc != GRN_SUCCESS) {
      return rc;
    }
    buf_tid = 0;
  }
  buf_term = &builder->buf.buf->terms[buf_tid];
  buf_term->tid = builder->chunk.tid;
  if (builder->n_cinfos > 0) {
    buf_term->tid |= CHUNK_SPLIT;
  }
  buf_term->size_in_buffer = 0;
  buf_term->pos_in_buffer = 0;
  buf_term->size_in_chunk = builder->chunk.enc_offset;
  buf_term->pos_in_chunk = builder->buf.chunk_offset;

  if (grn_logger_pass(ctx, GRN_LOG_DEBUG)) {
    grn_obj token;
    GRN_DEFINE_NAME(builder->ii);
    GRN_TEXT_INIT(&token, 0);
    grn_ii_get_term(ctx, builder->ii, builder->chunk.tid, &token);
    GRN_LOG(ctx, GRN_LOG_DEBUG,
            "[ii][builder][register][chunks] "
            "<%.*s>: "
            "<%.*s>(%u): "
            "n_chunks=<%u> "
            "chunk=<%u>/<%u>(%u)/(%u) "
            "encoded_chunk_size=<%" GRN_FMT_SIZE ">",
            name_size, name,
            (int)GRN_TEXT_LEN(&token), GRN_TEXT_VALUE(&token),
            builder->chunk.tid,
            builder->n_cinfos,
            builder->buf.chunk_offset,
            builder->buf.chunk_size,
            builder->buf.chunk_size - builder->buf.chunk_offset,
            builder->buf.ii->chunk->header->segment_size,
            builder->chunk.enc_offset);
    GRN_OBJ_FIN(ctx, &token);
  }
  grn_memcpy(builder->buf.chunk + builder->buf.chunk_offset,
             builder->chunk.enc_buf, builder->chunk.enc_offset);
  builder->buf.chunk_offset += builder->chunk.enc_offset;

  a = array_get(ctx, builder->ii, builder->chunk.tid);
  if (!a) {
    grn_obj token;
    GRN_DEFINE_NAME(builder->ii);
    GRN_TEXT_INIT(&token, 0);
    grn_ii_get_term(ctx, builder->ii, builder->chunk.tid, &token);
    MERR("[ii][builder][register][chunks] "
         "failed to allocate an array in segment: "
         "<%.*s>: "
         "<%.*s>(%u): "
         "max_n_segments=<%u>",
         name_size, name,
         (int)GRN_TEXT_LEN(&token), GRN_TEXT_VALUE(&token),
         builder->chunk.tid,
         builder->ii->seg->header->max_segment);
    GRN_OBJ_FIN(ctx, &token);
    return ctx->rc;
  }
  a[0] = grn_ii_pos_pack(builder->ii,
                         builder->buf.buf_id,
                         POS_LOFFSET_HEADER + POS_LOFFSET_TERM * buf_tid);
  a[1] = builder->df;
  array_unref(ctx, builder->ii, builder->chunk.tid);

  builder->buf.buf->header.nterms++;
  builder->n_cinfos = 0;
  grn_ii_builder_chunk_clear(ctx, &builder->chunk);
  return GRN_SUCCESS;
}

static grn_rc
grn_ii_builder_commit(grn_ctx *ctx, grn_ii_builder *builder)
{
  uint32_t i;
  grn_rc rc;
  grn_table_cursor *cursor;

  for (i = 0; i < builder->n_blocks; i++) {
    uint64_t value;
    rc = grn_ii_builder_read_from_block(ctx, builder, i, &value);
    if (rc != GRN_SUCCESS) {
      return rc;
    }
    builder->blocks[i].tid = value;
  }

  cursor = grn_table_cursor_open(ctx, builder->ii->lexicon,
                                 NULL, 0, NULL, 0, 0, -1, GRN_CURSOR_BY_KEY);
  for (;;) {
    grn_id tid = grn_table_cursor_next(ctx, cursor);
    if (tid == GRN_ID_NIL) {
      break;
    }
    builder->chunk.tid = tid;
    builder->chunk.rid = GRN_ID_NIL;
    builder->df = 0;
    for (i = 0; i < builder->n_blocks; i++) {
      if (tid == builder->blocks[i].tid) {
        rc = grn_ii_builder_read_to_chunk(ctx, builder, i);
        if (rc != GRN_SUCCESS) {
          return rc;
        }
      }
    }
    if (builder->chunk.n == 0) {
      /* This term does not appear. */
      continue;
    }
    if (builder->n_cinfos == 0) {
      grn_bool packed;
      rc = grn_ii_builder_pack_chunk(ctx, builder, &packed);
      if (rc != GRN_SUCCESS) {
        return rc;
      }
      if (packed) {
        continue;
      }
    }
    rc = grn_ii_builder_register_chunks(ctx, builder);
    if (rc != GRN_SUCCESS) {
      return rc;
    }
  }
  grn_table_cursor_close(ctx, cursor);
  if (grn_ii_builder_buffer_is_assigned(ctx, &builder->buf)) {
    rc = grn_ii_builder_buffer_flush(ctx, &builder->buf);
    if (rc != GRN_SUCCESS) {
      return rc;
    }
  }
  return GRN_SUCCESS;
}

grn_rc
grn_ii_build2(grn_ctx *ctx, grn_ii *ii, const grn_ii_builder_options *options)
{
  grn_rc rc, rc_close;
  grn_ii_builder *builder;
  rc = grn_ii_builder_open(ctx, ii, options, &builder);
  if (rc == GRN_SUCCESS) {
    rc = grn_ii_builder_append_source(ctx, builder);
    if (rc == GRN_SUCCESS) {
      rc = grn_ii_builder_commit(ctx, builder);
    }
    rc_close = grn_ii_builder_close(ctx, builder);
    if (rc == GRN_SUCCESS) {
      rc = rc_close;
    }
  }
  if (rc != GRN_SUCCESS) {
    grn_obj_flush(ctx, (grn_obj *)ii);
  }
  return rc;
}

grn_rc
grn_ii_wal_recover(grn_ctx *ctx, grn_ii *ii)
{
  if (GRN_CTX_GET_WAL_ROLE(ctx) == GRN_WAL_ROLE_NONE) {
    return GRN_SUCCESS;
  }

  if (!grn_wal_exist(ctx, (grn_obj *)ii)) {
    return GRN_SUCCESS;
  }

  grn_obj_set_error(ctx,
                    (grn_obj *)ii,
                    GRN_FUNCTION_NOT_IMPLEMENTED,
                    GRN_ID_NIL,
                    "[ii][wal][recover]",
                    "not implemented");
  return ctx->rc;
}

grn_rc
grn_ii_warm(grn_ctx *ctx, grn_ii *ii)
{
  grn_rc rc = grn_io_warm(ctx, ii->seg);
  if (rc == GRN_SUCCESS) {
    rc = grn_io_warm(ctx, ii->chunk);
  }
  return rc;
}
