MySQL is the most popular open-source relational database management system. Oracle's acquisition of Sun and thereby of MySQL raised doubts about the vision of development, causing the appearance of forks, drop-in replacements of MySQL, which are becoming increasingly popular. In this thesis we therefore explored compatibility, features, and performance enhancements of the most popular fork MariaDB. In the first part we briefly presented MySQL and its forks, then described in more detail MariaDB's features and compare them to MySQL's. In the second part we presented the test environment, the benchmark tool, and the tests that were used to measure both DBMSs' performance. We then visualized and analyzed the benchmark results, concluding that while newer version of MySQL is considerably improved, most operations are carried out faster in MariaDB, which is in compliance with the developers' statements. Furthermore, MariaDB offers several highly useful features that MySQL does not yet include.