The following is via a blog post by Asher Feldman, Site Architect, Wikipedia on Wikipedia Adopts MariaDB.
What was migrated?
- English Wikipedia
- German Wikipedia
What was this migrated from? MySQL 5.1 based on the Facebook patch, build r3753.
Why? Quote: MariaDB’s optimizer enhancements, the feature set of Percona’s XtraDB (many overlap with the Facebook patch, but I particularly like add-ons such as the ability to save the buffer pool LRU list, avoiding costly warmups on new servers), and of Oracle’s MySQL 5.5 provide compelling reasons to consider upgrading. Equally important, as supporters of the free culture movement, the Wikimedia Foundation strongly prefers free software projects; that includes a preference for projects without bifurcated code bases between differently licensed free and enterprise editions. We welcome and support the MariaDB Foundation as a not-for-profit steward of the free and open MySQL related database community.
Responsive MariaDB Team: "Along the way, a pair of bugs in MariaDB 5.5.28 and 5.5.29 were identified, one of which was a rare but potentially severe performance regression related to a new query optimizer feature. The MariaDB team was very responsive and quick to offer solutions, complete with test cases."
On performance: "For our most common query type, 95th percentile times over an 8-hour period dropped from 56ms to 43ms and the average from 15.4ms to 12.7ms. 50th percentile times remained a bit better with the 5.1-facebook build over the sample period, 0.185ms vs. 0.194ms. Many query types were 4-15% faster with MariaDB 5.5.30 under production load, a few were 5% slower, and nothing appeared aberrant beyond those bounds."