QUERY PLAN
Limit (cost=66.23..66.25 rows=10 width=203)
-> Sort (cost=66.23..66.33 rows=43 width=203)
Sort Key: s.status, u.pinyin_shortcut, s.target_completed_at, s.updated_at DESC
-> HashAggregate (cost=64.87..65.30 rows=43 width=203)
Group Key: s.id, u.id
-> Hash Left Join (cost=18.24..64.65 rows=43 width=203)
Hash Cond: (s.head_of = u.id)
-> Seq Scan on tbl_tasks s (cost=0.00..46.30 rows=43 width=196)
Filter: ((parent_id IS NULL) AND (task_group_id = 106))
-> Hash (cost=16.44..16.44 rows=144 width=7)
-> Seq Scan on tbl_users u (cost=0.00..16.44 rows=144 width=7)