QUERY PLAN
GroupAggregate (cost=49.85..50.12 rows=13 width=12)
Group Key: parent_id
-> Sort (cost=49.85..49.90 rows=18 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..49.48 rows=18 width=4)
Filter: (parent_id = ANY ('{1596,1647,1720}'::integer[]))