P0-[4.0 bug hunting]-[WHERE clause]-Wrong NULL value evaluation result in INCORRECT query results #64
Description
Bug Report
1. What did you do?
Running wreck-it with the default command line.
mysql> desc table_int_float;
+-----------+---------+------+------+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------+---------+------+------+---------+----------------+
| id | int(16) | NO | PRI | NULL | auto_increment |
| col_int | int(16) | YES | | NULL | |
| col_float | float | YES | MUL | NULL | |
+-----------+---------+------+------+---------+----------------+
3 rows in set (0.00 sec)
mysql> select col_float from table_varchar_float;
+-----------+
| col_float |
+-----------+
| NULL |
| -1 |
| -0.1 |
| NULL |
| 1.5 |
| 0.1 |
| NULL |
| NULL |
| 0 |
| 0.5 |
| NULL |
| NULL |
| -0.1 |
| 1 |
| NULL |
| 1.5 |
| NULL |
| NULL |
| NULL |
+-----------+
19 rows in set (0.00 sec)
mysql> SELECT * FROM table_varchar_float WHERE !(table_varchar_float.col_float and 1) IS NULL;
Empty set (0.00 sec)
2. What did you expect to see?
It should return some rows in the table (where the col_float=NULL).
mysql> select !(NULL and 1) is NULL;
+-----------------------+
| !(NULL and 1) is NULL |
+-----------------------+
| 1 |
+-----------------------+
1 row in set (0.00 sec)
3. What did you see instead?
It returns empty set.
4. What version of TiDB are you using? (tidb-server -V or run select tidb_version(); on TiDB)
mysql> select tidb_version();
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tidb_version() |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Release Version: v4.0.0-rc
Git Commit Hash: 79db9e30ab8f98ac07c8ae55c66dfecc24b43d56
Git Branch: heads/refs/tags/v4.0.0-rc
UTC Build Time: 2020-04-08 07:32:25
GoVersion: go1.13
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)