QUERY PLAN
Limit (cost=44.58..44.59 rows=5 width=148)
-> Sort (cost=44.58..44.59 rows=5 width=148)
Sort Key: s.status, u.pinyin_shortcut, s.target_completed_at, s.updated_at DESC
-> Group (cost=44.49..44.52 rows=5 width=148)
Group Key: s.id, u.id
-> Sort (cost=44.49..44.50 rows=5 width=148)
Sort Key: s.id, u.id
-> Hash Left Join (cost=9.13..44.43 rows=5 width=148)
Hash Cond: (s.head_of = u.id)
-> Seq Scan on tbl_tasks s (cost=0.00..35.29 rows=5 width=141)
Filter: (task_group_id = 192)
-> Hash (cost=7.39..7.39 rows=139 width=7)
-> Seq Scan on tbl_users u (cost=0.00..7.39 rows=139 width=7)