QUERY PLAN
GroupAggregate (cost=51.04..51.19 rows=8 width=12)
Group Key: parent_id
-> Sort (cost=51.04..51.07 rows=9 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..50.90 rows=9 width=4)
Filter: (parent_id = ANY ('{1596,1734,1747,1727}'::integer[]))