QUERY PLAN
GroupAggregate (cost=51.97..52.07 rows=5 width=12)
Group Key: parent_id
-> Sort (cost=51.97..51.99 rows=6 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..51.90 rows=6 width=4)
Filter: (parent_id = ANY ('{1596,1644,1641,1631,1630,1629}'::integer[]))