QUERY PLAN
GroupAggregate (cost=51.30..51.59 rows=14 width=12)
Group Key: parent_id
-> Sort (cost=51.30..51.35 rows=19 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..50.90 rows=19 width=4)
Filter: (parent_id = ANY ('{1596,1641,1647,1687}'::integer[]))