QUERY PLAN
GroupAggregate (cost=50.97..51.06 rows=5 width=12)
Group Key: parent_id
-> Sort (cost=50.97..50.98 rows=6 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..50.89 rows=6 width=4)
Filter: (parent_id = ANY ('{1535,1662,1661,1667,1669}'::integer[]))