MySQL and PostgreSQL power the vast majority of modern web applications. Both are open-source, mature, and capable, but they adhere to different design philosophies that influence their suitability for different projects.
MySQL / MariaDB: The Speed and Simplicity Choice
MySQL built its reputation on speed and ease of use. It is the "M" in the famous LAMP stack and powers WordPress, Facebook, and countless other platforms.
- Strengths: Extremely fast for read-heavy workloads (typical websites), simpler replication setup, and massive community support.
- Weaknesses: Historically less strict adherence to SQL standards, though this has improved significantly in version 8.0+.
- Best For: Content Management Systems (CMS), e-commerce product catalogs, and web applications where read speed matters most.
PostgreSQL: The Features and Integrity Choice
PostgreSQL styles itself as "The World's Most Advanced Open Source Relational Database." It focuses on strict standards compliance, data integrity, and complex feature sets comparable to Oracle or SQL Server.
- Strengths: Superior handling of complex queries (JOINs), stronger ACID reliability, native JSON support (turning it into a viable NoSQL hybrid), and extensibility (e.g., PostGIS for geospatial data).
- Weaknesses: Slightly more complex configuration and historically slower for simple reads (though the gap has narrowed appropriately).
- Best For: Financial systems, scientific data analysis, complex enterprise applications, and anywhere data integrity is paramount.
The Verdict
If you are building a standard web app or blog, MySQL is a proven, high-performance default. If you are building a complex application dealing with financial transactions, geospatial data, or intricate data relationships, PostgreSQL's advanced features make it the superior long-term choice.