MariaDB Definition MariaDB is an open source relational database management system (DBMS) that is a compatible drop-in replacement for the widely used MySQL database technology. It was created as a software fork of MySQL by developers who played key roles in building the original database; they devised MariaDB in 2009 in response to Oracle Corp.'s acquisition of MySQL. MariaDB is based on SQL and supports ACID-style data processing with guaranteed atomicity, consistency, isolation and durabi...