Details
Description
Description:
In theory, the result of sql1 ⊆ the result of sql2:
SELECT f1 FROM (SELECT (c1-~LN(4)) AS f1 FROM t) AS t1 where f1 != 1; -- sql1 |
SELECT f1 FROM (SELECT (c1-~LN(4)) AS f1 FROM t) AS t1 where 1; -- sql2 |
Because the condition of sql2 (where 1) is always true, but the condition of sql1 (where f1 != 1) may be false.
However, the value 2 changed to -1.8446744073709552e19 after changing f1 != 1 to 1, seems like a logical bug:
mysql> select version(); |
+-----------------------------------------+ |
| version() |
|
+-----------------------------------------+ |
| 10.11.1-MariaDB-1:10.11.1+maria~ubu2204 |
|
+-----------------------------------------+ |
1 row in set (0.00 sec) |
|
mysql> SELECT f1 FROM (SELECT (c1-~LN(4)) AS f1 FROM t) AS t1 where f1 != 1; |
+------+ |
| f1 |
|
+------+ |
| 2 |
|
+------+ |
1 row in set (0.00 sec) |
|
mysql> SELECT f1 FROM (SELECT (c1-~LN(4)) AS f1 FROM t) AS t1 where 1; |
+------------------------+ |
| f1 |
|
+------------------------+ |
| -1.8446744073709552e19 |
|
+------------------------+ |
1 row in set (0.00 sec) |
How to repeat:
drop table if exists t; |
CREATE TABLE t (c1 FLOAT UNSIGNED); |
INSERT INTO t VALUES (0); |
|
SELECT f1 FROM (SELECT (c1-~LN(4)) AS f1 FROM t) AS t1 where f1 != 1; |
SELECT f1 FROM (SELECT (c1-~LN(4)) AS f1 FROM t) AS t1 where 1; |
Hope these can be helpful for your debugging:
1. The bug cannot be reproduced after deleting '~';
2. We look for the first version of the bug in all docker images (with format x.x.x) of https://hub.docker.com/_/mariadb/tags
We found that the bug first occurred in mariadb:5.5.40, and we can't find any order versions in dockerhub:
MariaDB [TEST]> select version(); |
+-----------------------------+ |
| version() |
|
+-----------------------------+ |
| 5.5.40-MariaDB-1~wheezy-log |
|
+-----------------------------+ |
1 row in set (0.00 sec) |
|
MariaDB [TEST]> SELECT f1 FROM (SELECT (c1-~LN(4)) AS f1 FROM t) AS t1 where f1 != 1; |
+------+ |
| f1 |
|
+------+ |
| 2 |
|
+------+ |
1 row in set (0.00 sec) |
|
MariaDB [TEST]> SELECT f1 FROM (SELECT (c1-~LN(4)) AS f1 FROM t) AS t1 where 1; |
+------------------------+ |
| f1 |
|
+------------------------+ |
| -1.8446744073709552e19 |
|
+------------------------+ |
1 row in set (0.00 sec) |