Execution example:: > select --table Comments --query posted_by:tasukuchan --output_columns comment --drilldown hash_tags [[0,1317212783.21601,0.000313114],[[[4],[["comment","ShortText"]],["åã®æ¸ãè¾¼ã¿ããã¹ããã¹ãã"],["@daijiro ãããã¨ãï¼"],["groongaãªã #groonga"],["groongaéçºå宿ã®ããç¾½ç°ç©ºæ¸¯ã«æ¥ã¾ããï¼ #groonga #travel"]],[[2],[["_key","ShortText"],["_nsubrecs","Int32"]],["groonga",2],["travel",1]]]]