QUERY PLAN
GroupAggregate (cost=46.71..46.95 rows=12 width=12)
Group Key: parent_id
-> Sort (cost=46.71..46.75 rows=16 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..46.39 rows=16 width=4)
Filter: (parent_id = ANY ('{1596,1647}'::integer[]))