MariaDB was created to be a drop-in replacement for MySQL. Widenius says that as long as MySQL has a larger user base than MariaDB, remaining drop-in compatibility will be essential, in order to make the transition between the databases trivial.

“However, being a drop-in replacement doesn’t stop us from changing the underlying code to make it faster and better or add new features,” he says.

via Dead database walking: MySQL’s creator on why the future belongs to MariaDB – MariaDB, open source, mysql, Oracle – Computerworld.