QUERY PLAN
GroupAggregate (cost=156.14..156.27 rows=6 width=12)
Group Key: parent_id
-> Sort (cost=156.14..156.17 rows=9 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..156.00 rows=9 width=4)
Filter: (parent_id = ANY ('{1600,1598,1592,1591,1583,1537,1536,1535}'::integer[]))