Execution example::

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