QUERY PLAN
GroupAggregate (cost=61.19..61.36 rows=9 width=12)
Group Key: parent_id
-> Sort (cost=61.19..61.22 rows=10 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..61.02 rows=10 width=4)
Filter: (parent_id = ANY ('{1456,1509,1557,1558,1559,1560,1561,1562,1565,1566}'::integer[]))