Execution example::

  select Entries --filter 'content @ "fast"' --output_columns content
  # [
  #   [
  #     0, 
  #     1337566253.89858, 
  #     0.000355720520019531
  #   ], 
  #   [
  #     [
  #       [
  #         2
  #       ], 
  #       [
  #         [
  #           "content", 
  #           "Text"
  #         ]
  #       ], 
  #       [
  #         "I started to use groonga. It's very fast!"
  #       ], 
  #       [
  #         "I also started to use mroonga. It's also very fast! Really fast!"
  #       ]
  #     ]
  #   ]
  # ]
