Execution example::

  load --table Memos
  [
  {"_key": "Groonga is fast",          "user": "alice", "tag": "groonga"},
  {"_key": "Mroonga is fast",          "user": "alice", "tag": "mroonga"},
  {"_key": "Groonga is very good!",    "user": "alice", "tag": "groonga"},
  {"_key": "Droonga is fast",          "user": "david", "tag": "droonga"},
  {"_key": "Groonga is a HTTP server", "user": "david", "tag": "groonga"}
  ]
  # [[0, 1337566253.89858, 0.000355720520019531], 5]
