# groonga - An open-source fulltext search engine and column store.

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# 7.3.50. `table_rename`

## 7.3.50.1. Summary

`table_rename` command renames a table.

It is a light operation. It just changes a relationship between name and the table object. It doesn't copy table and its column values.

It is a dangerous operation. You must stop all operations including read operations while you run `table_rename`. If the following case is occurred, Groonga process may be crashed:

> - Starts an operation (like `select`) that accesses the table to be renamed by the current table name. The current table name is called as `the old table name` in the below because the table name is renamed.
> - Runs `table_rename`. The `select` is still running.
> - The `select` accesses the table to be renamed by the old table name. But the `select` can't find the table by the old name because the table has been renamed to the new table name. It may crash the Groonga process.

## 7.3.50.2. Syntax

This command takes two parameters.

All parameters are required:

    table_rename name new_name

## 7.3.50.3. Usage

Here is a simple example of `table_rename` command.

Execution example:

    table_create Users TABLE_PAT_KEY ShortText
    # [[0, 1337566253.89858, 0.000355720520019531], true]
    column_create Users score COLUMN_SCALAR Int32
    # [[0, 1337566253.89858, 0.000355720520019531], true]
    load --table Users
    [
    {"_key": "Alice",  "score": 2},
    {"_key": "Bob",    "score": 0},
    {"_key": "Carlos", "score": -1}
    ]
    # [[0, 1337566253.89858, 0.000355720520019531], 3]
    table_rename Users Players
    # [[0, 1337566253.89858, 0.000355720520019531], true]
    table_list
    # [
    #   [
    #     0,
    #     1337566253.89858,
    #     0.000355720520019531
    #   ],
    #   [
    #     [
    #       [
    #         "id",
    #         "UInt32"
    #       ],
    #       [
    #         "name",
    #         "ShortText"
    #       ],
    #       [
    #         "path",
    #         "ShortText"
    #       ],
    #       [
    #         "flags",
    #         "ShortText"
    #       ],
    #       [
    #         "domain",
    #         "ShortText"
    #       ],
    #       [
    #         "range",
    #         "ShortText"
    #       ],
    #       [
    #         "default_tokenizer",
    #         "ShortText"
    #       ],
    #       [
    #         "normalizer",
    #         "ShortText"
    #       ]
    #     ],
    #     [
    #       256,
    #       "Players",
    #       "/tmp/groonga-databases/commands_table_rename.0000100",
    #       "TABLE_PAT_KEY|PERSISTENT",
    #       "ShortText",
    #       null,
    #       null,
    #       null
    #     ]
    #   ]
    # ]
    select Players
    # [
    #   [
    #     0,
    #     1337566253.89858,
    #     0.000355720520019531
    #   ],
    #   [
    #     [
    #       [
    #         3
    #       ],
    #       [
    #         [
    #           "_id",
    #           "UInt32"
    #         ],
    #         [
    #           "_key",
    #           "ShortText"
    #         ],
    #         [
    #           "score",
    #           "Int32"
    #         ]
    #       ],
    #       [
    #         1,
    #         "Alice",
    #         2
    #       ],
    #       [
    #         2,
    #         "Bob",
    #         0
    #       ],
    #       [
    #         3,
    #         "Carlos",
    #         -1
    #       ]
    #     ]
    #   ]
    # ]

## 7.3.50.4. Parameters

This section describes parameters of `table_rename`.

### 7.3.50.4.1. Required parameters

All parameters are required.

#### 7.3.50.4.1.1. `name`

Specifies the table name to be renamed.

#### 7.3.50.4.1.2. `new_name`

Specifies the new table name.

## 7.3.50.5. Return value

The command returns `true` as body on success such as:

    [HEADER, true]

If the command fails, error details are in `HEADER`.

See Output format for `HEADER`.