QUERY PLAN
Limit (cost=68.19..68.21 rows=10 width=196)
-> Sort (cost=68.19..68.86 rows=269 width=196)
Sort Key: s.created_at DESC
-> HashAggregate (cost=59.68..62.37 rows=269 width=196)
Group Key: s.id, u.id
-> Nested Loop (cost=0.00..58.34 rows=269 width=196)
-> Seq Scan on tbl_users u (cost=0.00..8.16 rows=1 width=4)
Filter: ((id = 1000) AND (department_id = 10))
-> Seq Scan on tbl_tasks s (cost=0.00..47.49 rows=269 width=192)
Filter: ((parent_id IS NULL) AND (head_of = 1000))