QUERY PLAN
Limit (cost=68.78..68.80 rows=10 width=198)
-> Sort (cost=68.78..69.46 rows=273 width=198)
Sort Key: s.status, s.target_completed_at, s.updated_at DESC
-> HashAggregate (cost=60.15..62.88 rows=273 width=198)
Group Key: s.id, u.id
-> Nested Loop (cost=0.14..58.78 rows=273 width=198)
-> Index Scan using tbl_users_pkey on tbl_users u (cost=0.14..8.16 rows=1 width=4)
Index Cond: (id = 1000)
Filter: (department_id = 10)
-> Seq Scan on tbl_tasks s (cost=0.00..47.89 rows=273 width=194)
Filter: ((parent_id IS NULL) AND (head_of = 1000))