QUERY PLAN
GroupAggregate (cost=52.94..53.24 rows=15 width=12)
Group Key: parent_id
-> Sort (cost=52.94..52.99 rows=21 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..52.48 rows=21 width=4)
Filter: (parent_id = ANY ('{1596,1647,1727,1726,1724}'::integer[]))