I apparently have_community_features

Posted in: MySQL, Technical Track

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, date_format and similarly time_format and datetime_format).

It is undocumented. I cannot find it where it should be, at 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.

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.

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3 Comments. Leave new

Giuseppe Maxia
May 4, 2009 4:06 pm

Hi Sheeri,
“have_community_features” should definitely be documented. It was introduced in MySQL 5.0.37 (IIRC) to allow the inclusion of SHOW PROFILES when compiling the server.
It is used for the same purpose on 5.1 and 6.0.
Getting a YES or a NO depends on how the server was compiled. If your copy of 6.0 says “NO”, probably SHOW PROFILES was not included.

Hope this helps, pending documentation fixes.



Sheeri Cabral
May 4, 2009 6:28 pm

Giuseppe — thanx, this is good to know!

Henrik Ingo
May 5, 2009 4:16 am

@Giuseppe: I guessed that much. It is like the community only ever provided 1 feature to MySQL. But in 5.4 for example, suppose this variable says “NO”, does it mean the google patches were excluded and I can now enjoy less performance?

I’m just saying, taken literally it’s easy to see situations where this is not a meaningful variable.


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