QUERY PLAN
GroupAggregate (cost=47.73..47.77 rows=2 width=12)
Group Key: parent_id
-> Sort (cost=47.73..47.74 rows=2 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..47.73 rows=2 width=4)
Filter: (parent_id = ANY ('{1756,1757}'::integer[]))