QUERY PLAN
GroupAggregate (cost=48.10..48.35 rows=13 width=12)
Group Key: parent_id
-> Sort (cost=48.10..48.14 rows=17 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..47.75 rows=17 width=4)
Filter: (parent_id = ANY ('{1596,1647}'::integer[]))