QUERY PLAN
GroupAggregate (cost=48.23..48.48 rows=12 width=12)
Group Key: parent_id
-> Sort (cost=48.23..48.28 rows=17 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..47.89 rows=17 width=4)
Filter: (parent_id = ANY ('{1596,1647}'::integer[]))