QUERY PLAN
Aggregate (cost=56.11..56.12 rows=1 width=8)
-> Sort (cost=56.03..56.04 rows=5 width=231)
Sort Key: s.status, u.pinyin_shortcut, s.target_completed_at, s.updated_at DESC
-> Group (cost=55.94..55.97 rows=5 width=231)
Group Key: s.id, u.id
-> Sort (cost=55.94..55.95 rows=5 width=29)
Sort Key: s.id, u.id
-> Hash Left Join (cost=9.24..55.88 rows=5 width=29)
Hash Cond: (s.head_of = u.id)
-> Seq Scan on tbl_tasks s (cost=0.00..46.62 rows=5 width=34)
Filter: ((parent_id IS NULL) AND (task_group_id = 204))
-> Hash (cost=7.44..7.44 rows=144 width=7)
-> Seq Scan on tbl_users u (cost=0.00..7.44 rows=144 width=7)