Machiel Richards wrote:
> Hi All
>
>
>
> I hope that someone can assist me with this.
>
>
>
> We have a client with a production MySQL database running
> MySQL 5.0.
>
>
>
> Their slow query counts have skyrocketed over the last week
> and I found that their slow query logs are not enabled.
>
>
>
> However when trying to configure this I get the following
> message:
>
>
>
> mysql> set global log_slow_queries=ON;
>
> ERROR 1238 (HY000): Variable 'log_slow_queries' is a read only variable
>
> mysql>
>
>
>
> I did the same thing many times before on other databases
> but this specific one gives me this message.
>
>
>
> Can anyone perhaps give me some insight as to why i'm
> getting this and how to enable it (preferably without having to restart the
> database seeing it is a high availability production system)?
>
>
You can do what you described in version 5.1 but not in 5.0 . For 5.0
that variable is not dynamic. That means you cannot change it while the
system is running:
http://dev.mysql.com/doc/refman/5.0/en/server-options.html#option_mysqld_log-slow-queries
One way around this is to setup the machine with the Slow Query Log
enabled but to use a very large value of --long-query-time to
essentially ignore every query. Then, when you want to capture slow
queries, you reset --long-query-time to a reasonable value.
Unfortunately, this requires a restart to initialize. After that you can
adjust the --long-query-time to throttle the contents of the log.
http://dev.mysql.com/doc/refman/5.0/en/slow-query-log.html
http://dev.mysql.com/doc/refman/5.0/en/server-system-variables.html#sysvar_long_query_time
--
Shawn Green, MySQL Senior Support Engineer
Sun Microsystems, Inc.
Office: Blountville, TN
