MySQL

MySQL is one of the most widely deployed open-source relational databases, especially common in web stacks and as the storage layer behind countless WordPress, Rails, and PHP applications. It is owned by Oracle, with two prominent community forks: MariaDB (separate project since 2010) and Percona Server (a drop-in replacement with operational tooling).

Key features

• InnoDB engine. The default storage engine since MySQL 5.5: ACID transactions, row-level locking, MVCC, foreign keys.
• Replication. Mature primary-replica replication with semi-synchronous, asynchronous, and Group Replication options.
• Pluggable storage engines. InnoDB by default; MyISAM, MEMORY, Archive, and others available for niche workloads.
• JSON support. Native JSON columns since 5.7, with indexing via generated columns or multi-valued indexes.
• Mature ecosystem. Connectors for every language, broad managed offerings (RDS, Aurora, PlanetScale, Cloud SQL).

MySQL vs PostgreSQL

• MySQL is permissive by default and has historically focused on simplicity and replication speed; PostgreSQL is stricter and richer in types, extensions, and advanced SQL features.
• PostgreSQL has overtaken MySQL as the default for new projects in many parts of the industry; MySQL remains dominant in installed base and in specific stacks.