Description:
An Item_ref ref items in base_ref_items, but Item_rollup_group_item only exists in field_list. If an Item_ref reference to a constant with rollup, then the Item_ref's used_tables should be RAND_TABLE_BIT, but now it's 0.
This will cause wrong result.
mysql> CREATE TABLE t1 (a int primary key, b int);
Query OK, 0 rows affected (0.09 sec)
mysql> INSERT INTO t1 VALUES (1, 2);
Query OK, 1 row affected (0.01 sec)
mysql> SELECT 1 as x FROM t1 GROUP BY x WITH ROLLUP HAVING EXISTS (SELECT 1 FROM t1 WHERE x is NULL);
Empty set (0.00 sec)
mysql> EXPLAIN SELECT 1 as x FROM t1 GROUP BY x WITH ROLLUP HAVING EXISTS (SELECT 1 FROM t1 WHERE x is NULL);
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------------+
| 1 | SIMPLE | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | Impossible HAVING |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------------+
1 row in set, 2 warnings (0.00 sec)
How to repeat:
CREATE TABLE t1 (a int primary key, b int);
INSERT INTO t1 VALUES (1, 2);
SELECT 1 as x FROM t1 GROUP BY x WITH ROLLUP HAVING EXISTS (SELECT 1 FROM t1 WHERE x is NULL);
EXPLAIN SELECT 1 as x FROM t1 GROUP BY x WITH ROLLUP HAVING EXISTS (SELECT 1 FROM t1 WHERE x is NULL);
Suggested fix:
Find item in field_list for Item_ref and use that item to propagate used_tables
