PostgreSQL and MySQL are the two most popular open-source databases. Both work great for web apps, but have key differences.
SQL Standards Compliance
PostgreSQL closely follows the SQL standard. MySQL has many non-standard extensions and sometimes silently truncates data instead of raising errors.
Data Types
PostgreSQL is significantly richer:
- JSONB — binary JSON with indexing. MySQL supports JSON but without binary storage
- ARRAY — native arrays. MySQL doesn't have them
- UUID — native type in PostgreSQL, stored as CHAR(36) in MySQL
Window Functions
PostgreSQL has supported full window functions since 8.4 (2009). MySQL added them only in 8.0 (2018).
Performance
- Simple reads — MySQL often faster due to simpler planner
- Complex analytics — PostgreSQL significantly better thanks to its optimizer
- Concurrent access — PostgreSQL handles concurrent transactions better
When to Choose What?
PostgreSQL:
- Complex business logic and analytics
- JSON/geospatial data
- Strict typing and data integrity
- Extensibility
MySQL:
- Simple CRUD applications
- Maximum speed on simple queries
- Wide hosting support
- WordPress/PHP ecosystem