MariaDB

In short: An open-source database system that came about as a direct fork of MySQL, after Oracle acquired MySQL — largely compatible, but developed independently since.

In more detail: MariaDB was started in 2009 by the original MySQL developers, out of concern that Oracle might close MySQL off proprietarily. It remains API- and mostly drop-in compatible with MySQL to this day, but has since developed its own features (e.g. different storage engines).

In Depth

The fork and its motivation

The trigger for the fork was Oracle’s acquisition of MySQL’s then-owner, Sun Microsystems, in 2009/2010 — parts of the original MySQL community (above all MySQL co-founder Michael “Monty” Widenius) feared a commercial corporation might make future versions more proprietary, tighten licensing terms, or simply slow down development in favour of Oracle’s own database. They forked the last open MySQL state as a standalone project remaining under the GPL, named MariaDB (named after Widenius’s daughter Maria — MySQL itself was named after his other daughter, My).

Compatibility in practice

“Drop-in compatible” means in practice: the same SQL commands, the same network protocol, the same client libraries usually work unchanged against MariaDB as against MySQL — an application written for MySQL can, in most cases, be switched to a MariaDB instance without code changes, only the connection details change. Many Linux distributions (e.g. some Debian/Ubuntu variants) have even completely replaced MySQL with MariaDB in their standard package sources, without existing applications noticing anything — the package name mysql-server effectively installs MariaDB there.

Divergence over time

Over the years, the two projects have diverged: different storage engines (MariaDB, for example, comes with Aria and ColumnStore, which don’t exist in MySQL), different replication features for distributed database clusters, and different JSON support (MySQL introduced its own native JSON data type, MariaDB implements JSON functions somewhat differently). Very new MySQL features (e.g. certain extensions from more recent MySQL 8 versions) are therefore no longer guaranteed to be available 1:1 in MariaDB, and vice versa.

Cloud offerings

Like MySQL, MariaDB is also offered by the major cloud providers as a managed service (AWS RDS, Azure Database, Google Cloud SQL), which considerably simplifies operation (backups, scaling, updates) compared to a self-hosted server. For newer projects, PostgreSQL-based serverless offerings like NeonDB are increasingly gaining popularity, offering a different trade-off (automatic scaling, pay-per-use instead of fixed server costs).

See also: SQL, MySQL, NeonDB, PostgreSQL