PostgreSQL vs MySQL: Which Database to Choose?

PostgreSQL and MySQL are the two most popular open-source relational databases. PostgreSQL prioritizes standards compliance, extensibility, and advanced features. MySQL prioritizes simplicity, read performance, and ease of deployment. Both are production-proven at massive scale, powering applications from startups to enterprises handling billions of rows.

How do they handle JSON data?

PostgreSQL's JSONB type stores JSON in a binary format that supports GIN indexing, allowing fast queries on nested fields without parsing the document. You can use operators like @> for containment queries and ->> for field extraction directly in WHERE clauses. MySQL's JSON type stores documents as text with validation and provides functions like JSON_EXTRACT(), but indexing requires generated columns. For applications mixing relational and document patterns, PostgreSQL's JSONB is significantly more capable.

Which performs better for reads vs writes?

MySQL's InnoDB engine is optimized for simple read-heavy workloads and can be faster for basic SELECT queries with primary key lookups. PostgreSQL performs better on complex queries involving CTEs, window functions, lateral joins, and subqueries. For write-heavy workloads, PostgreSQL's MVCC implementation handles concurrent writes more efficiently. In practice, both scale to millions of queries per second when properly indexed and tuned — the query complexity matters more than the database choice.

What advanced features does PostgreSQL offer?

PostgreSQL includes features that MySQL lacks or implements partially: recursive CTEs, materialized views, table inheritance, range types, array types, custom aggregate functions, and an extension ecosystem that includes PostGIS for geospatial data, pgvector for AI embeddings, TimescaleDB for time-series, and Citus for horizontal sharding. PostgreSQL also supports row-level security policies, making it a strong fit for multi-tenant applications.

How do replication strategies compare?

MySQL uses binary log replication, which is simple to set up and supports both asynchronous and semi-synchronous modes. MySQL Group Replication provides multi-primary support. PostgreSQL offers streaming replication (physical) and logical replication, which allows replicating specific tables or transforming data during replication. Logical replication enables zero-downtime major version upgrades and selective data distribution — a significant operational advantage.

When to use which?

Choose PostgreSQL when you need advanced SQL features, JSONB document storage, full-text search, geospatial queries, custom types, or row-level security. PostgreSQL is the better default choice for new applications and is required for extensions like pgvector (AI/ML) and PostGIS.

Choose MySQL when you need a simpler database with a gentler learning curve, your workload is primarily simple reads, you're using a framework with strong MySQL integration (WordPress, Laravel), or when you need MySQL-specific managed services like PlanetScale's branching workflow.

Key takeaways

• PostgreSQL offers more advanced features: JSONB, full-text search, extensions, row-level security
• MySQL is simpler to set up and can be faster for straightforward read-heavy workloads
• PostgreSQL's extension ecosystem (PostGIS, pgvector, TimescaleDB) is unmatched
• Both support ACID transactions, MVCC, and scale to massive datasets with proper tuning
• PostgreSQL is the better default for new projects; MySQL when simplicity or framework compatibility matters