[debian-mysql] Serious mess while upgrading mysql server

[Clint Byrum]

Excerpts from Didier Kryn's message of 2014-11-04 07:16:42 -0800:
>      Dear mysql Debian maintainers,
> 
>      As the administrator of a few Dell PowerEdge servers running Debian 
> Wheezy, I made a general upgrade of two machines today. This triggered 
> an upgrade of our mysql servers which had several consequences:
> 
>      1) the new version (5.5.40) is not fully compatible with version 
> 5.5.38 . The mysql administrator complained that his service would not 
> work without changing configuration files.

Hi Didier, I'm sorry that you've had a difficult time with the latest
update. It would be useful if you would include exactly _what_ had to
be changed.

In reading the release notes I don't see anything about preference
files:

http://dev.mysql.com/doc/relnotes/mysql/5.5/en/news-5-5-39.html
http://dev.mysql.com/doc/relnotes/mysql/5.5/en/news-5-5-40.html

>      2) the simple fact of restarting a server while it is involved in 
> databases replications also causes serious harm according to him.
> 
>      Would you be kind enough to consider the following suggestions:
> 
>      1) when a new version is not fully compatible with the previous 
> one, maybe the two versions might be in the repository, but the new one 
> *not* considered an upgrade of the old one, so that routine upgrades do 
> not touch it but the administrator must explicitely install one and 
> remove the other (like for java-6 vs java-7).
> 

We've been assured several times by the MySQL dev team that they're
doing a large amount of testing to ensure that these patch releases do
not introduce backward-incompatible behavior unless it is required to
close a security hole. They also promised to call them out if they are
necessary in the release notes. There are none called out in the 2
releases we recently shipped into stable, so I'm not sure we could have
done more than we already did here.

>      2) Even for simple upgrades (the ones which do not touch the user 
> interface), when about to stop the mysql server, display a warning about 
> the possible consequences and ask if the administrator really wants to 
> continue.
> 

There is a documented interface for preventing package installs from
touching running services. Please see 'man invoke-rc.d', specifically
the 'INIT SCRIPT POLICY' section.