The main goal of migrating to MariaDB is not performance driven. More so,
I think it's in WMF's and the open source communities interest to coalesce
around the MariaDB Foundation as the best route to ensuring a truly open
and well supported future for mysql derived database technology.
Performance gains along the way are icing on the cake.
Several months ago I noticed Wikipedia's Ganglia (cluster performance monitoring software) is publicly accessible. Check out db59 (mentioned in the note) amongst the other servers:
Hopefully this will get more people to adopt mariadb and be free of the legal and upgrade uncertainties of mysql. I installed it a few weeks ago and the result is -exactly- like mysql.
Wikipedia seems like the perfect system for a document store like CouchDB. I would be curious to know if they examined it and, if so, found it lacking.
Also, most MediaWiki installs use plugins, and those plugins often create their own database tables. So RDBMS is pretty much baked into the MediaWiki culture.
However, MediaWiki is fairly well abstracted from any particular RDBMS implementation. Everything from creating tables to making a join is done through an API.
MariaDB is a (almost) drop-in replacement for MySQL, CouchDB is a totally different concept that would require nearly a complete re-write of their backend. I doubt they considered it.
My guess is that they have been using MySQL for a long, long time (possibly since the beginning)m, and see no need to migrate to something different. MariaDB is API-compatible with MySQL, so this migration will not involve much changes at the client side; it's mostly thorough testing that needs to be done.
Document DB's aren't an invention of the past 10 years. SAS was invented in the 60's, Lotus Notes in the 80's. XML Databases were all the rage during the dotcom bubble.
The difference today is that open source projects have made document stores and 'nosql' technologies more accessible.
Note that unless your mysql server has more than 4 (physical) cores, you aren't going to see any performance improvements from any variation/fork of mysql. 8 cores is where things start to diverge under load.
Why do they care about whether the technology is derived from MySQL or not? Postgres makes way more sense for pretty much every application out there now. What am I missing?
They aren't starting from scratch. Migrating your database is a complex and risky project, and not the kind of thing you do unless you have a very clear, very pressing reason, like horrible performance and stability issues, or saving tens of millions of dollars in licenses. Migrating to MariaDB is more like upgrading a minor version, with minimal risk and zero downtime. And they have a lot of experience in MySQL, almost all of it transferable to MariaDB.
I use MariaDB on my Mac for most things that require MySQL. It's a drop in replacement for most things. Is there a special edge case with media wiki they had to solve or is it now just formally announced as being supported?
So, it's pretty much a drop-in replacement. But as with everything, time m ust be spent testing and so on before rolling it out to production. I believe a transition to MariaDB has been planned for a while now.
I remember I had problems with insert statements when previously with mysql inserts without default values worked but MariaDB was strict in this case and these inserts failed...
