QUERY PLAN
GroupAggregate (cost=151.56..151.64 rows=4 width=12)
Group Key: parent_id
-> Sort (cost=151.56..151.57 rows=5 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..151.50 rows=5 width=4)
Filter: (parent_id = ANY ('{1622,1618,1617,1616,1615}'::integer[]))