Improve function name
Improve function name

It is a filter command. So "get_" is storange. A command that names
"get_" will extract information by itself.

mroonga/mroonga,mroonga/mroonga,yoku0825/mroonga,mroonga/mroonga,naoa/mroonga,yoku0825/mroonga,mroonga/mroonga,yoku0825/mroonga,yoku0825/mroonga,naoa/mroonga,yoku0825/mroonga,naoa/mroonga,naoa/mroonga,yoku0825/mroonga,naoa/mroonga,naoa/mroonga