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.<br>
<br>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. <br>
<br>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. <br>
<br>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. <br>
<br>As the MariaDB roll-out proceeds, I will provide updates on wikitech-l. <br><br>Best,<br>Asher<br><br><div class="gmail_quote">On Wed, Feb 13, 2013 at 5:19 AM, Petr Bena <span dir="ltr"><<a href="mailto:benapetr@gmail.com" target="_blank">benapetr@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Okay - so what is outcome? Should we migrate beta cluster? Are we going to use it in production?<br></div>
<div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, Feb 13, 2013 at 2:08 PM, Chad <span dir="ltr"><<a href="mailto:innocentkiller@gmail.com" target="_blank">innocentkiller@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>On Wed, Feb 13, 2013 at 8:05 AM, bawolff <<a href="mailto:bawolff%2Bwn@gmail.com" target="_blank">bawolff+wn@gmail.com</a>> wrote:<br>
> Umm there was a thread several months ago about how it is used on several<br>
> of the slave dbs, if I recall.<br>
><br>
<br>
</div>Indeed, you're looking for "mariadb 5.5 in production for english wikipedia"<br>
<br>
<a href="http://www.gossamer-threads.com/lists/wiki/wikitech/319925" target="_blank">http://www.gossamer-threads.com/lists/wiki/wikitech/319925</a><br>
<span><font color="#888888"><br>
-Chad<br>
</font></span><div><div><br>
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