QUERY PLAN
Limit (cost=305.83..305.83 rows=1 width=251)
InitPlan 1 (returns $0)
-> Aggregate (cost=146.83..146.84 rows=1 width=32)
-> Seq Scan on tbl_tasks s_1 (cost=0.00..143.86 rows=1186 width=13)
Filter: (tree_path IS NOT NULL)
-> Sort (cost=158.99..159.00 rows=1 width=251)
Sort Key: s.status, u.pinyin_shortcut, s.target_completed_at, s.created_at DESC
-> Group (cost=158.97..158.98 rows=1 width=251)
Group Key: s.id, u.pinyin_shortcut
-> Sort (cost=158.97..158.98 rows=1 width=251)
Sort Key: s.id, u.pinyin_shortcut
-> Nested Loop Left Join (cost=0.00..158.96 rows=1 width=251)
Join Filter: (u.id = s.head_of)
-> Seq Scan on tbl_tasks s (cost=0.00..149.79 rows=1 width=248)
Filter: ((parent_id IS NULL) AND (tree_path @> $0) AND (task_group_id = 201))
-> Seq Scan on tbl_users u (cost=0.00..7.41 rows=141 width=7)