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PostgreSQL vs MySQL: Which Database Should You Choose?

Postgres and MySQL are the two most popular open-source databases. How they differ on features, JSON, extensions, performance, hosting and ecosystem — and why most new apps (and AI app builders) default to Postgres.

PostgreSQL ("Postgres") and MySQL are the two most widely used open-source relational databases. Both store data in tables, both speak SQL, both run some of the largest websites on the internet. For most new apps either would work — but there are real differences, and one is the more common default today.

(New to databases? Start with what is a database? and SQL for beginners.)

The quick answer

  • Starting a new app with no constraints: PostgreSQL. More features, a huge extension ecosystem, and the default for most modern tools and hosts.
  • Your framework, host or team is built around MySQL (classic PHP hosting, WordPress, an existing MySQL app): MySQL is a fine, proven choice.

A little history

  • MySQL (1995) became famous as the "M" in the LAMP stack that powered the early web. It's now owned by Oracle. A community fork, MariaDB, split off in 2009 and is largely compatible.
  • PostgreSQL (with roots in the 1980s, SQL since the mid-1990s) is developed by an independent community and has a reputation for correctness and features. A new major version arrives every autumn.

Where they differ

Features

Postgres has a broader feature set:

  • JSONB — store and index JSON documents efficiently, so one database handles both structured and flexible data. (Postgres JSONB.) MySQL has a JSON type too, but Postgres's indexing and querying of JSON is more capable.
  • Extensions — add major capabilities: pgvector for AI embeddings (pgvector tutorial), PostGIS for maps and locations, and many more.
  • Row-level security — rules in the database about which rows each user can access. Supabase is built on this. (Supabase RLS explained.)
  • Transactional schema changes — a migration that fails halfway rolls back cleanly. In MySQL, most schema changes commit immediately, so a failed migration can leave things half-done. (Database migrations.)
  • Richer types and SQL — arrays, ranges, RETURNING, more powerful full-text search (Postgres full-text search).

Strictness

Postgres is strict by default: insert text that's too long or a value of the wrong type and you get an error. Older MySQL configurations were known for silently truncating or converting data; modern MySQL defaults to strict mode too, but you may meet legacy setups that aren't.

Performance

Both are fast. MySQL has a long-standing reputation for very fast simple reads; Postgres excels at complex queries. For a typical app, your indexes and query design matter far more than the choice of engine. Don't choose on benchmarks.

Connections

Postgres uses a process per connection, so apps with many short-lived connections (especially serverless ones) usually need a connection pooler. MySQL's thread-per-connection model copes with large numbers of connections more cheaply. See Postgres connection pooling.

Ecosystem and hosting

Both are offered by every major cloud. Most of the new wave of developer databases — Supabase, Neon and others — are Postgres-based, and AI app builders overwhelmingly default to Postgres. MySQL remains everywhere in traditional web hosting, WordPress and many established companies.

Side by side

PostgreSQL MySQL
Licence / owner Open source, community Open source (GPL), Oracle
JSON support JSONB, excellent indexing JSON type, more limited
Extensions Rich (pgvector, PostGIS…) Limited
Row-level security Built in No equivalent
Transactional schema changes Yes Mostly no
Many connections Needs a pooler at scale Handles well
Typical default for new apps Yes Common in PHP/WordPress

What about switching later?

Possible but not trivial: SQL dialects differ, data types differ, and your ORM or queries may need changes. Pick deliberately at the start. If you use an ORM, switching is easier but still needs testing.

The summary

  • Both are mature, fast, open-source relational databases.
  • Postgres has more features: JSONB, extensions like pgvector, row-level security, transactional migrations.
  • MySQL is simpler with connections and ubiquitous in traditional hosting.
  • For a new app with no constraints, choose Postgres.

EasySpawn provisions PostgreSQL, MySQL, MongoDB and Redis on every server, with connection details passed to your app as environment variables like DATABASE_URL — Postgres is the recommended default. See how it works or join the waitlist.

Related: SQL vs NoSQL · Which Database Should an AI-Built App Use? · Is SQLite Good Enough for Production? · Postgres Connection Strings Explained

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