[Labs-l] Maria DB

[Asher Feldman]

For most projects, I recommend using the official packages available via
the MariaDB projects own apt repo.

The official packages are based on the Debian mysql packaging where
installing the server package also installs a default database created
around generic config defaults, a debian mysql maintenance user with a
randomly generated password, and scripts (including init) that assume
privileged access via that user. That is, installing the packages provides
you with a fresh running working database with generic defaults suitable
for a small server, and certain admin tasks automated. I think that's what
the average labs and general users wants and expects.

The packages I've built for production use at wmf strips out all of the
debianisms, the debian project script rewrites, the pre/post install
actions. They also leave debug symbols in the binaries and have compiler
flag tweaks, but do not at this stage contain any source
patches. Installing the server package doesn't create a default db, or
provide an environment where you can even start the server on a fresh sever
install without further work. Probably not a good choice for most labs
users.

On Wednesday, February 13, 2013, Petr Bena wrote:

> thanks for updates.
>
> Can you tell me what is a difference between maria db you are using and
> the version that is recommended for use on ubuntu?
>
>
> On Wed, Feb 13, 2013 at 6:58 PM, Asher Feldman <afeldman at wikimedia.org<javascript:_e({}, 'cvml', 'afeldman at wikimedia.org');>
> > wrote:
>
>> The production migration to MariaDB was paused for a time by the EQIAD
>> datacenter migration and issues involving other projects that took up my
>> time, but the trial production roll-out will resume this month.  All signs
>> still point to our using it in production.
>>
>> I did a lot of query testing on an enwiki MariaDB 5.5 slave over the
>> course
>> of more than a month before the first production deployment.  Major
>> version
>> migrations with mysql and derivatives are not to be taken lightly in
>> production environments.  At a minimum, one must be concerned about query
>> optimizer changes making one particular query type significantly slower.
>> In the case of the switch to 5.5, there are several default behavior
>> changes over 5.1 that can break applications or change results.  Hence,
>> some serious work over a plodding time frame before that first production
>> slave switch.
>>
>> Despite those efforts, a couple weeks after the switch, I saw a query
>> generated by what seems to be a very rare edge case from that AFTv4
>> extension that violated stricter enforcement of unsigned integer types in
>> 5.5, breaking replication and requiring one off rewriting and execution of
>> the query locally to ensure data consistency before skipping over it.  I
>> opened a bug, Mathias fixed the extension, and I haven't seen any other
>> compatibility issues from AFTv4 or anything else deployed on enwiki.
>>
>> That said, other projects utilize different extensions, so all of my
>> testing that has gone into enwiki cannot be assumed to fully cover
>> everything else.  Because of that, and because I want to continue
>> proceeding with caution for all of our projects, this will continue to be
>> a
>> slow and methodical process at this stage.  Bugs in extensions that aren't
>> used by English Wikipedia may be found and require fixing along the way.
>>
>> As the MariaDB roll-out proceeds, I will provide updates on wikitech-l.
>>
>> Best,
>> Asher
>>
>> On Wed, Feb 13, 2013 at 5:19 AM, Petr Bena <benapetr at gmail.com<javascript:_e({}, 'cvml', 'benapetr at gmail.com');>>
>> wrote:
>>
>> > Okay - so what is outcome? Should we migrate beta cluster? Are we going
>> to
>> > use it in production?
>> >
>> >
>> > On Wed, Feb 13, 2013 at 2:08 PM, Chad <innocentkiller at gmail.com<javascript:_e({}, 'cvml', 'innocentkiller at gmail.com');>>
>> wrote:
>> >
>> >> On Wed, Feb 13, 2013 at 8:05 AM, bawolff <bawolff+wn at gmail.com<javascript:_e({}, 'cvml', 'bawolff%2Bwn at gmail.com');>>
>> wrote:
>> >> > Umm there was a thread several months ago about how it is used on
>> >> several
>> >> > of the slave dbs, if I recall.
>> >> >
>> >>
>> >> Indeed, you're looking for "mariadb 5.5 in production for english
>> >> wikipedia"
>> >>
>> >> http://www.gossamer-threads.com/lists/wiki/wikitech/319925
>> >>
>> >> -Chad
>> >>
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