PostgreSQL and MySQL are the two most widely used open-source relational databases. Both store data in tables with clear relationships, support transactions and run reliably for years. MySQL is owned by Oracle, and MariaDB is a popular community fork of it. PostgreSQL is developed by an independent global community.
For most business apps either will work. The differences matter when you need advanced features, AI search or specific hosting.
Side-by-side comparison
| What matters | PostgreSQL | MySQL |
|---|---|---|
| License and ownership | Open source, community developed | Open source edition, owned by Oracle |
| Advanced data types | Arrays, JSONB, ranges and more | Fewer built-in types |
| JSON support | JSONB with indexing | JSON type, somewhat more limited |
| Extensions | Rich, such as PostGIS and pgvector | Fewer extensions |
| Vector search for AI | Via the pgvector extension | Depends on version and fork |
| Simple read-heavy workloads | Fast | Very fast |
| Complex queries and reporting | Strong | Good |
| WordPress and many PHP apps | Not the default | The standard choice |
| Managed hosting options | All major clouds | All major clouds |
| Best fit | Custom apps, SaaS, analytics, AI features | WordPress, classic PHP apps, simple workloads |
What they have in common
Both are relational databases: data lives in tables, relationships are enforced and changes happen in transactions, so a payment and its invoice are saved together or not at all. Both handle millions of rows on modest servers, support replication for backups and read scaling, and have decades of production use behind them.
For a typical business app with customers, orders and bookings, either will serve you well. That is worth saying first, because the choice is rarely a disaster either way.
Data types and flexibility
PostgreSQL offers a wider range of data types, including arrays, ranges and JSONB, a binary JSON format that can be indexed and queried efficiently. That lets you store flexible data, such as custom fields that vary by customer, without giving up the structure of a relational database.
MySQL also supports JSON, and recent versions have improved it, but PostgreSQL's handling is generally considered more capable for complex queries on JSON data.
Extensions and AI features
PostgreSQL's extension system is one of its biggest strengths. PostGIS adds location queries used by mapping and logistics apps. The pgvector extension adds vector search, which lets you store embeddings for AI features next to your business data and search by meaning. For many projects, that removes the need for a separate vector database.
Performance
Benchmarks vary with workload and settings, and both databases are fast when well configured. MySQL has a reputation for speed on simple read-heavy workloads. PostgreSQL has a strong query planner that handles complex joins and reporting well. In real projects, indexes, query design and caching matter far more than the choice between the two.
Fit with your existing software
WordPress, WooCommerce and many classic PHP applications are built for MySQL. If you run them, MySQL is the natural choice. Many modern frameworks and hosted platforms default to PostgreSQL, including Supabase, and most ORMs support both equally well.
Running them day to day
Both need the same basics: automatic backups, tested restores, monitoring, updates and sensible user permissions. Managed services from the major clouds take care of most of this for either database. On your own servers, both are straightforward to run with good documentation and tools.
Letting AI query your database
Both can be connected to AI assistants through MCP servers, so staff can ask questions of the data in plain English. The rules are the same for both: read-only users, a replica rather than the primary database, and logs of every query. See how to connect AI to your database safely, the PostgreSQL MCP server and the MySQL MCP server.
If you are thinking about switching
Moving an existing application from one database to the other is possible but rarely urgent. Data types differ, some queries need rewriting and the application must be retested thoroughly. It is worth it when you need a feature the current database lacks, such as vector search or advanced data types, or when you are rebuilding the application anyway. Otherwise, the time is usually better spent on indexes, queries and backups in the database you already have.
If you do switch, run both databases side by side for a while, compare results for key reports and move traffic in stages. Keep a tested way back until the new setup has proven itself in production.
Which one to choose
Choose PostgreSQL when
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You are building a new custom app or SaaS product.
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You need flexible data, such as JSON alongside tables.
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You plan AI features that need vector search.
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Reporting and complex queries matter.
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You want location data with PostGIS.
Choose MySQL when
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You run WordPress, WooCommerce or another MySQL-based app.
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Your team and hosting are built around MySQL.
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The workload is simple and read-heavy.
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You are extending an existing MySQL system.
What we usually recommend
For new custom applications, SaaS products and anything with AI search, we recommend PostgreSQL. Its data types, JSON support and extensions such as pgvector mean one database can often cover what would otherwise need two or three systems.
For WordPress sites and existing MySQL applications, stay with MySQL unless you have a clear reason to move. A migration costs time and carries risk, and MySQL serves those workloads well. See database design and data migration.