MySQL Bugs: #62095: Query cache failed to set size

Bug #62095	Query cache failed to set size
Submitted:	5 Aug 2011 15:09	Modified:	9 Sep 2011 18:12
Reporter:	Yoachan Rayon	Email Updates:
Status:	No Feedback	Impact on me:	None
Category:	MySQL Server: Query Cache	Severity:	S2 (Serious)
Version:	5.0.92-community MySQL Community Edition	OS:	Linux (CentOS 5.6 x-64)
Assigned to:		CPU Architecture:	Any

Description:
I have a machine with CentOS 5.6 x_64 which used to be fine using bundled mySQL (5.0.77). But few hours ago I did upgrade to 5.0.92, and suddently query_cache_size was reset to zero.

When I tried to do SET GLOBAL query_cache_size = 268435456;

it response with a warning

Query cache failed to set size 268435456; new query cache size is 0

How to repeat:
run command SET GLOBAL query_cache_size = 268435456;

Suggested fix:
query_cache_size set to 268435456

Had you build 5.0.92 yourself from sources?

I do not see any problem with current code:

macbook-pro:5.0 openxs$ bin/mysql -uroot test
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.0.95-debug Source distribution

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> SET GLOBAL query_cache_size = 268435456;
Query OK, 0 rows affected (0.45 sec)

mysql> show variables like 'query%';
+------------------------------+-----------+
| Variable_name                | Value     |
+------------------------------+-----------+
| query_alloc_block_size       | 8192      | 
| query_cache_limit            | 1048576   | 
| query_cache_min_res_unit     | 4096      | 
| query_cache_size             | 268435456 | 
| query_cache_type             | ON        | 
| query_cache_wlock_invalidate | OFF       | 
| query_prealloc_size          | 8192      | 
+------------------------------+-----------+
7 rows in set (0.01 sec)

Yes, I got it bundled with WHM/CPanel.
I think it was upgraded along with WHM.

Currently I'm downloading a copy of it in my local machine just to do test,
but I think I was wrong to post a ticket here for 5.0.92 is not MySQL latest release..... If I think it was buggy I suppose to upgrade it.....

Sorry for the trouble...

In my case, the "SET GLOBAL VARIABLE query_cache_size" only works for value less than 12MB .... if somehow it ring a bell.
12MB and any number above will give me that warning I mentioned earlier.

Thank you for the feedback.

Please send us output of ulimit -a for user you are running mysqld as.

No feedback was provided for this bug for over a month, so it is
being suspended automatically. If you are able to provide the
information that was originally requested, please do so and change
the status of the bug back to "Open".