[ { "Plan": { "Node Type": "Limit", "Parallel Aware": false, "Plans": [ { "Node Type": "Merge Append", "Parent Relationship": "Outer", "Parallel Aware": false, "Sort Key": [ "his_robot_register_y2019m3.time_stamp DESC" ], "Plans": [ { "Node Type": "Index Scan", "Parent Relationship": "Member", "Parallel Aware": false, "Scan Direction": "Backward", "Index Name": "pk_his_robot_register_y2019m3", "Relation Name": "his_robot_register_y2019m3", "Alias": "his_robot_register_y2019m3", "Index Cond": "((booth_id = 2) AND (zone_id = 9) AND (robot_id = 34) AND (time_stamp >= '2019-03-11 00:00:00'::timestamp without time zone) AND (time_stamp <= '2019-03-12 00:00:00'::timestamp without time zone))", "Filter": "(factory_id = 701)" } ] } ] } } ]
단순 조회하는건데 query plan에 merge append가 있는데 이게 뭘 의미하는건가요? |