Do you have_community_features? I do!
SHOW GLOBAL VARIABLES LIKE 'have_community_features'; +-------------------------+-------+ | Variable_name | Value | +-------------------------+-------+ | have_community_features | YES | +-------------------------+-------+ 1 row in set (0.00 sec)
I am pretty sure this is one of those variables that MySQL has put in as an unused placeholder, but for now, it is not even documented as unused (as are table_lock_wait_timeout, http://dev.mysql.com/doc/refman/5.1/en/server-system-variables.html, and a Google search restricted to the site dev.mysql.com turns up only one match, which is not useful: http://www.google.com/search?q=site%3Adev.mysql.com+have_community_features
I wonder if using this parameter could have been an easier way to deal with the release of MySQL 5.4. I wonder what it is used for, or what it will be used for. In all the versions of 5.1 I have access to, I see the parameter in there (from 5.1.29 – 5.1.32).
More interestingly, on a 6.0.5 server:
Server version: 6.0.5-alpha-community MySQL Community Server (GPL) Type 'help;' or '\h' for help. Type '\c' to clear the buffer. mysql> SHOW GLOBAL VARIABLES LIKE 'have_community_features'; +-------------------------+-------+ | Variable_name | Value | +-------------------------+-------+ | have_community_features | NO | +-------------------------+-------+ 1 row in set (0.03 sec)
This has been logged as Bug 44651.