What is it
PostgreSQL is an object-relational DBMS focused on complex queries and extensibility. MySQL is a relational DBMS optimized for high read speeds and ease of deployment.
| Parameter | PostgreSQL | MySQL |
|---|---|---|
| License | PostgreSQL License | GPL / Commercial |
| Default Isolation | Read Committed | Repeatable Read |
| Index types | B-tree, GIN, GiST, BRIN, Hash | B-tree, Hash, Full-text |
| ACID Compliance | Full | InnoDB only |
| JSON support | JSONB (binary) | JSON (textual) |
Performance
PostgreSQL uses a process-per-connection model, ensuring stability for complex JOINs and analytical workloads. Parallel query execution allows efficient use of multi-core CPUs. MySQL uses a thread-per-connection model, offering lower overhead for simple OLTP scenarios with high read concurrency. In heavy write-concurrency benchmarks, PostgreSQL 15+ often outperforms MySQL 8.0 due to its advanced MVCC implementation.
Configuration & complexity
Configuring PostgreSQL requires understanding memory parameters. The main postgresql.conf includes shared_buffers (typically 25% RAM) and work_mem for sorts. MySQL is simpler to start with; the key parameter is innodb_buffer_pool_size. PostgreSQL is stricter regarding data types and integrity: inserting an invalid date triggers an error, while MySQL might convert it to a default value depending on SQL modes.
When to choose what
- PostgreSQL: Financial systems, GIS (via PostGIS), scientific data, complex enterprise ERPs.
- MySQL: Standard websites, CMS (WordPress, Drupal), microservices with straightforward data schemas.
Cost / licensing
PostgreSQL is completely free for commercial use without restrictions. MySQL is owned by Oracle and distributed under GPL. Embedding MySQL into proprietary software without releasing source code requires a commercial license.
Ecosystem & integrations
PostgreSQL features powerful extensions: PostGIS for geospatial data, TimescaleDB for time-series, and Citus for sharding. MySQL leads in replication tools and cloud provider support. Popular MySQL forks include Percona Server and MariaDB.
Verdict
Choose PostgreSQL if data integrity, complex relations, and extensibility are priorities. Choose MySQL for standard web projects where read speed and simple replica scaling are critical.