QUERY PLAN
Aggregate (cost=57.57..57.58 rows=1 width=8)
-> Sort (cost=57.45..57.47 rows=8 width=228)
Sort Key: s.target_completed_at, s.updated_at DESC
-> Group (cost=57.27..57.33 rows=8 width=228)
Group Key: s.id, u.id
-> Sort (cost=57.27..57.29 rows=8 width=26)
Sort Key: s.id
-> Nested Loop (cost=0.14..57.15 rows=8 width=26)
-> 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..48.91 rows=8 width=34)
Filter: ((parent_id IS NULL) AND (head_of = 1000) AND (status = '0'::smallint))