From: Shawn Green
Date: April 27 2012 1:26pm
Subject: Re: RFE: Allow to use version-specific my.cnf files
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Hello Honza,

On 4/27/2012 4:35 AM, Honza Horak wrote:
> On 04/25/2012 05:52 PM, Andrés Tello wrote:
>> Reads interesting, but...
>>
>> Why would you need that?
>>
>> I mean... If I run several databases in the same hardware, I use
>> completely
>> diferent paths for evertying, so I can have atomic, clean and specific
>> files for each instance/version of the database....
>
> Thanks for your opinion.
>
> You're right, it doesn't make too much sense regarding system-wide
> configuration files, such as /etc/my.cnf. A real use case I see is when
> we speak about users' config files, like ~/.my.cnf.
>
> Let's say we have two different MySQL versions on one hardware, then
> it's possible we'll need a bit different options for each instance.
>
> MySQL unfortunately doesn't distinguish between user-specific (usually
> called rc files) and system-wide config files. Trying to have the patch
> simple, I applied the feature to all config files (which was not
> necessary).
>
> The attached patch now is a bit more complicated, but restricts the
> feature only for config files in user's home directory. I believe this
> makes more sense, than the original one.
>
> Any comments welcome again.
>
> Cheers,

I frequently need to have multiple versions ready to operate on my 
machine at any time. I solved the configuration file problems by only 
setting them up in the basedir of the installed version.

For those special occasions when I need to configure multiple copies of 
the same version, I create a separate set of --datadir folders and craft 
separate configuration files for both. I start mysqld using the 
--defaults-file option and point that at the special file for each 
instance.

As a matter of convenience, if you need to constantly run with multiple 
instances on the same host and if any one of those may need to be using 
a different version than the others, then the utility mysqld_multi may 
be what you need to be looking at.  Each instance you manage by the 
script can have their own separate set of settings all stored in the 
same, common, configuration file. Check it out:
http://dev.mysql.com/doc/refman/5.1/en/mysqld-multi.html



-- 
Shawn Green
MySQL Principal Technical Support Engineer
Oracle USA, Inc. - Hardware and Software, Engineered to Work Together.
Office: Blountville, TN