QUERY PLAN
GroupAggregate (cost=47.43..47.52 rows=5 width=12)
Group Key: parent_id
-> Sort (cost=47.43..47.44 rows=6 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..47.35 rows=6 width=4)
Filter: (parent_id = ANY ('{1647,1641,1596}'::integer[]))