QUERY PLAN
GroupAggregate (cost=45.92..46.00 rows=4 width=12)
Group Key: parent_id
-> Sort (cost=45.92..45.93 rows=5 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..45.86 rows=5 width=4)
Filter: (parent_id = ANY ('{1596,1647}'::integer[]))