Up until 2012, MySQL held a near-monopoly on the title, having won every year since at least 2001 (except for 2002, won by PostgreSQL).
Since 2013, however, it’s been all MariaDB, and now MariaDB is going for a hat-trick of wins.
2015 was a great year for MariaDB development, and the latest stable release, 10.1, includes Galera Cluster, a true multi-master solution, table, tablespace and log encryption, page compression, replication enhancements, numerous optimizations, and a whole lot more. See What is MariaDB 10.1 for a detailed breakdown.
To vote in the database category, go to the Database of the Year forum. If you don’t already have a LinuxQuestions account, you’ll have to register, and make at least one post, before being allowed to vote.
This year there are also a number of new categories – see them all in the 2015 LinuxQuestions.org Members Choice Awards forum.