The next release of Fedora, Fedora 19 may ship with MariaDB as the default database instead of the more popular MySQL. This decision is mainly taken because Fedora developers have always strived to ship the latest and greatest open source software in Fedora Operation System, and steps taken by Oracle are making MySQL to move more towards being closed source.

Muktware earlier covered this issue. This fear surfaced when a recent release of MySQL has bug fixes but without any test cases associated with it. What it meant was that a developer working with MySQL had no clue if the bug was actually fixed or not. Also, it seems that Oracle has removed revision history which stored data about code changes, who made the change and why. This will make it difficult to know if the bugs reported are actually fixed.

Also, Oracle has a bad reputation of dealing with open source software. Like they had acquired Java and OpenOffice but not has made significant improvements and developments with them. Later, they dumped OpenOffice back to Apache community.

Quoting from the mailing list:

MariaDB is a fork of the MySQL database project that provides a drop-in
replacement for MySQL. It preserves API/ABI compatibility with MySQL and
adds some new features.

The original company behind MySQL, MySQL AB, were bought out by Sun which was
then bought by Oracle. Recent changes made by Oracle indicate they are moving
the MySQL project to be more closed. They are no longer publishing any useful
information about security issues (CVEs), and they are not providing complete
regression tests any more, and a very large fraction of the mysql bug database
is now not public.

MariaDB, which was founded by some of the original MySQL developers, has a more
open-source attitude and an active community. We have found them to be much
easier to work with, especially in regards to security matters.

For developers, MariaDB is hundred percent compatible with MySQL, and is also more feature rich and secure. MySQL will continue to stay in Fedora official repos for sometime, but will be subsequently removed later on.