QUERY PLAN
GroupAggregate (cost=76.00..76.31 rows=15 width=12)
Group Key: parent_id
-> Sort (cost=76.00..76.05 rows=21 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..75.54 rows=21 width=4)
Filter: (parent_id = ANY ('{1456,1509,1557,1558,1559,1560,1561,1562,1565,1566,1576,1577,1578,1596,1668,1686,1734,1745,1768}'::integer[]))