QUERY PLAN
GroupAggregate (cost=174.46..174.71 rows=9 width=12)
Group Key: parent_id
-> Sort (cost=174.46..174.51 rows=21 width=4)
Sort Key: parent_id
-> Seq Scan on tbl_tasks (cost=0.00..174.00 rows=21 width=4)
Filter: (parent_id = ANY ('{1618,1617,1616,1615,1614,1613,1611,1600,1598,1592,1591,1583,1582,1568,1566,1562,1561,1560,1559,1558}'::integer[]))