QUERY PLAN
Limit (cost=57.64..57.66 rows=10 width=195)
-> Sort (cost=57.64..57.67 rows=14 width=195)
Sort Key: s.created_at
-> Group (cost=57.27..57.37 rows=14 width=195)
Group Key: s.id, u.id
-> Sort (cost=57.27..57.30 rows=14 width=195)
Sort Key: s.id, u.id
-> Hash Left Join (cost=9.24..57.00 rows=14 width=195)
Hash Cond: (s.head_of = u.id)
-> Seq Scan on tbl_tasks s (cost=0.00..47.73 rows=14 width=191)
Filter: ((parent_id IS NULL) AND (task_group_id = 203))
-> Hash (cost=7.44..7.44 rows=144 width=4)
-> Seq Scan on tbl_users u (cost=0.00..7.44 rows=144 width=4)