QUERY PLAN
GroupAggregate (cost=50.95..51.05 rows=6 width=12)
Group Key: parent_id
-> Sort (cost=50.95..50.96 rows=6 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..50.87 rows=6 width=4)
Filter: (parent_id = ANY ('{1813,1834,1835,1837}'::integer[]))