QUERY PLAN
GroupAggregate (cost=155.84..155.95 rows=5 width=12)
Group Key: parent_id
-> Sort (cost=155.84..155.86 rows=8 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..155.72 rows=8 width=4)
Filter: (parent_id = ANY ('{1600,1598,1592,1591,1583,1537,1536,1535}'::integer[]))