QUERY PLAN
Limit (cost=59.20..59.23 rows=10 width=195)
-> Sort (cost=59.20..59.34 rows=57 width=195)
Sort Key: s.created_at
-> HashAggregate (cost=57.40..57.97 rows=57 width=195)
Group Key: s.id, u.id
-> Hash Left Join (cost=9.24..57.11 rows=57 width=195)
Hash Cond: (s.head_of = u.id)
-> Seq Scan on tbl_tasks s (cost=0.00..47.73 rows=57 width=191)
Filter: ((parent_id IS NULL) AND (status = '0'::smallint))
-> 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)