QUERY PLAN
GroupAggregate (cost=152.83..152.92 rows=4 width=12)
Group Key: parent_id
-> Sort (cost=152.83..152.85 rows=6 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..152.75 rows=6 width=4)
Filter: (parent_id = ANY ('{1562,1561,1560,1559,1558,1557}'::integer[]))