| Performance | Traditionally faster for simple read-heavy workloads. InnoDB buffer pool provides excellent caching. Optimized for web application query patterns. | Superior performance for complex queries, joins, and write-heavy workloads. Advanced query planner makes better optimization decisions for complex SQL. |
| Features | Covers standard relational needs well. JSON support exists but is less mature than PostgreSQL's JSONB. Window functions, CTEs, and lateral joins now supported. | Feature-rich: JSONB, arrays, range types, full-text search, window functions, CTEs, materialized views, table inheritance, custom types, and extensions. |
| JSON/Document | JSON and JSON_TABLE support in MySQL 8+. Functional but less performant and flexible than PostgreSQL's JSONB. Adequate for simple JSON storage. | JSONB is a first-class binary JSON type with indexing (GIN), querying, and update operators. Effectively gives you document database capabilities within a relational database. |
| Extensibility | Plugin system for storage engines and authentication. Less extensible than PostgreSQL. Relies on MySQL forks (MariaDB, Percona) for advanced features. | Highly extensible with custom types, operators, functions, and extensions. PostGIS (geospatial), pg_vector (AI embeddings), TimescaleDB (time-series), Citus (distributed) add specialized capabilities. |
| Replication | Strong replication story: async, semi-sync, Group Replication, InnoDB Cluster, MySQL Router. Well-documented and battle-tested at massive scale. | Streaming replication, logical replication, and multiple third-party solutions (Patroni, Citus). Reliable but historically more complex to set up than MySQL replication. |
| Hosting & Ecosystem | Available everywhere: AWS RDS, PlanetScale, Vitess, every shared host. WordPress ecosystem alone ensures massive tooling support. | Available on all major clouds: AWS RDS, Supabase, Neon, Railway. Growing ecosystem with Supabase bringing PostgreSQL to a new generation of developers. |