QUERY PLAN
GroupAggregate (cost=60.52..60.67 rows=8 width=12)
Group Key: parent_id
-> Sort (cost=60.52..60.54 rows=10 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..60.35 rows=10 width=4)
Filter: (parent_id = ANY ('{1578,1577,1576,1566,1562,1561,1560,1559,1558,1557}'::integer[]))