QUERY PLAN
Limit (cost=49.81..49.83 rows=5 width=152)
-> Sort (cost=49.81..49.83 rows=5 width=152)
Sort Key: s.status, u.pinyin_shortcut, s.target_completed_at, s.updated_at DESC
-> Group (cost=49.72..49.76 rows=5 width=152)
Group Key: s.id, u.id
-> Sort (cost=49.72..49.73 rows=5 width=152)
Sort Key: s.id, u.id
-> Hash Left Join (cost=9.17..49.66 rows=5 width=152)
Hash Cond: (s.head_of = u.id)
-> Seq Scan on tbl_tasks s (cost=0.00..40.48 rows=5 width=145)
Filter: (task_group_id = 195)
-> Hash (cost=7.41..7.41 rows=141 width=7)
-> Seq Scan on tbl_users u (cost=0.00..7.41 rows=141 width=7)