Bug #10724 Incorrect column headers returned when using @@local to reference a variable
Submitted: 19 May 2005 1:02 Modified: 7 Aug 2005 0:54
Reporter: Harrison Fisk Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server Severity:S3 (Non-critical)
Version:4.1.12 OS:Windows (Windows XP)
Assigned to: Jim Winstead CPU Architecture:Any

[19 May 2005 1:02] Harrison Fisk 
Description:
If you use the @@local.variable syntax in a query, the column headers instead come back as @@session.variable.  They should come back as @@local, since that is what you gave in the query.

How to repeat:
mysql> select @@local.max_allowed_packet;
+------------------------------+
| @@session.max_allowed_packet |
+------------------------------+
|                      1048576 |
+------------------------------+
1 row in set (0.00 sec)

Suggested fix:
The column header should not be changed and should instead return exactly what is passed in (in this case it should return @@local.max_allowed_packet).
[19 May 2005 2:14] MySQL Verification Team 
c:\mysql\bin>mysql -uroot
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1 to server version: 4.1.13-debug

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> select @@local.max_allowed_packet;
+------------------------------+
| @@session.max_allowed_packet |
+------------------------------+
|                      1048576 |
+------------------------------+
1 row in set (0.13 sec)

miguel@hegel:~/dbs/4.1$ bin/mysql -uroot
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4 to server version: 4.1.13-debug-log

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> select @@local.max_allowed_packet;
+------------------------------+
| @@session.max_allowed_packet |
+------------------------------+
|                      1047552 |
+------------------------------+
1 row in set (0.00 sec)
[25 May 2005 0:17] Jim Winstead 
This needs a ruling from our standards czars.

Related to this, the case of the session/global/local specifier is not preserved, and @@version (@@global.version, etc) is especially strange -- it is always named @@VERSION.
[16 Jun 2005 0:34] 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/internals/26050
[29 Jun 2005 11:21] Magnus Blåudd 
Approved.
[25 Jul 2005 18:25] 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/internals/27561
[2 Aug 2005 2:23] Jim Winstead 
Fixed in 4.1.14 and 5.0.11.
[7 Aug 2005 0:54] Mike Hillyer 
Documented in 4.1.14 and 5.0.11 changelogs:

<listitem><para>
 <literal>SELECT @@local...</literal> returned <literal>@@session...</literal> in the column header. (Bug #10724)
</para></listitem>