QUERY PLAN
GroupAggregate (cost=51.70..51.95 rows=13 width=12)
Group Key: parent_id
-> Sort (cost=51.70..51.74 rows=17 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..51.35 rows=17 width=4)
Filter: (parent_id = ANY ('{1596,1647,1727,1724}'::integer[]))