| Bug #21231 | A wrong result for a simple query with a subquery on information schema | ||
|---|---|---|---|
| Submitted: | 22 Jul 2006 17:26 | Modified: | 2 Aug 2006 18:52 |
| Reporter: | Igor Babaev | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Server: Information schema | Severity: | S2 (Serious) |
| Version: | 5.0 | OS: | Any (all) |
| Assigned to: | Igor Babaev | CPU Architecture: | Any |
[23 Jul 2006 1:16]
MySQL Verification Team
Thank you for the bug report.
[23 Jul 2006 1:19]
MySQL Verification Team
Sorry I forgot to mention 5.1 is already fixed:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3 to server version: 5.1.12-beta-debug
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> select table_name from information_schema.tables
-> where table_name=(select max(table_name)
-> from information_schema.tables);
+------------+
| table_name |
+------------+
| VIEWS |
+------------+
1 row in set (0.07 sec)
mysql>
[25 Jul 2006 2:03]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/9524
[25 Jul 2006 19:10]
Sergey Petrunya
Approving the fix as a backport of part of 5.1's changes
[2 Aug 2006 18:47]
Evgeny Potemkin
The function get_all_tables filling all information schema tables reset lex->sql_command to SQLCOM_SHOW_FIELDS. After this the function could evaluate partial conditions related to some columns. If these conditions contained a subquery over information schema it led to a wrong evaluation and a wrong result set. Fixed in 5.0.25, 5.1.12
[2 Aug 2006 18:52]
Paul DuBois
Noted in 5.0.25, 5.1.12 changelogs.
Description: The following simple query on information schema returns an empty set though apparently it must return at least one row as the table tables from information_schema is not empty. select table_name from information_schema.tables where table_name=(select max(table_name) from information_schema.tables) How to repeat: mysql> select version(); +--------------+ | version() | +--------------+ | 5.0.23-debug | +--------------+ 1 row in set (0.00 sec) mysql> select table_name from information_schema.tables -> where table_name=(select max(table_name) -> from information_schema.tables); Empty set (0.00 sec) Suggested fix: Fix is ready and will be applied after a formal verification.