QUERY PLAN
GroupAggregate (cost=51.33..51.62 rows=14 width=12)
Group Key: parent_id
-> Sort (cost=51.33..51.38 rows=20 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..50.90 rows=20 width=4)
Filter: (parent_id = ANY ('{1596,1647,1727,1724}'::integer[]))