MySQL and PostgreSQL are the two most popular open-source relational databases. Both are mature, fast and reliable enough for nearly any application. The differences lie in features, philosophy and ecosystem — and those decide which fits your project better.

The short answer

  • Choose PostgreSQL for new applications where you control the stack: richer SQL, better JSON support, powerful extensions, strict data integrity.
  • Choose MySQL (or MariaDB) when your software expects it — WordPress, Magento, many PHP apps — or when your team already knows it well.

Neither choice will hold back a typical web application.

Comparison

MySQL 8 PostgreSQL 17
License GPL (Oracle), commercial editions exist PostgreSQL License (permissive)
Architecture Thread per connection Process per connection
Default storage engine InnoDB Single built-in engine (heap + MVCC)
SQL standards Good, with some MySQL-specific behaviour Very close to the standard
JSON JSON type, functions, indexes via generated columns json and jsonb with GIN indexes and rich operators
Advanced SQL CTEs, window functions (since 8.0) CTEs, window functions, LATERAL, MERGE, partial and expression indexes
Extensions Limited plugin model Huge ecosystem: PostGIS, pgvector, TimescaleDB, pg_trgm…
Full-text search Built in (InnoDB FTS) Built in, more flexible (tsvector, ranking, dictionaries)
Replication Async/semi-sync, Group Replication Streaming (physical), logical replication
Connection handling Lightweight threads Heavier processes — use PgBouncer at scale
Typical apps WordPress, Magento, Drupal, many PHP apps Django, Rails, modern SaaS, GIS, analytics

Data integrity and correctness

PostgreSQL is strict by default: invalid dates, truncated strings and type mismatches are errors. MySQL 8 is also strict by default (STRICT_TRANS_TABLES), a big improvement over older versions, but legacy apps sometimes run in permissive modes where data is silently adjusted.

PostgreSQL also offers transactional DDL — you can roll back a failed migration, including CREATE TABLE and ALTER TABLE. In MySQL, DDL statements commit implicitly, so a migration that fails halfway can leave the schema in between states.

Features developers notice

PostgreSQL extras that frequently matter:

  • jsonb — binary JSON with indexing; handles semi-structured data without a separate document database.
  • Partial indexes — CREATE INDEX … WHERE status = 'active'.
  • Arrays, ranges, enums, UUIDs as native types.
  • Extensions — pgvector for AI embeddings, PostGIS for geographic data, pg_trgm for fuzzy search.
  • RETURNING on INSERT/UPDATE/DELETE (MariaDB supports it on some statements; MySQL doesn’t).

MySQL strengths:

  • Simpler to operate for many teams; huge amount of hosting knowledge and tooling.
  • Very fast for simple primary-key lookups and read-heavy web workloads.
  • Mature, easy-to-set-up replication used at enormous scale.
  • First-class support in nearly every PHP application.

Performance

For typical web workloads, the difference is dominated by schema design, indexes, queries and caching, not the engine. Rough tendencies:

  • MySQL/InnoDB does very well on simple, high-concurrency reads and writes by primary key.
  • PostgreSQL shines on complex queries, joins, analytics and mixed workloads, thanks to its planner and index types.
  • PostgreSQL’s process-per-connection model needs connection pooling (PgBouncer) with hundreds of clients; MySQL handles many connections more cheaply.

Benchmark your workload if performance is decisive.

Operations on a VPS

Both run well on a small server:

  • Memory: give InnoDB’s buffer pool or PostgreSQL’s shared_buffers + OS cache enough RAM for the working set.
  • Backups: mysqldump vs pg_dump for logical backups; XtraBackup/mariadb-backup vs pgBackRest for physical ones.
  • Upgrades: MySQL minor upgrades are in-place; PostgreSQL major upgrades need pg_upgrade or dump/restore.

Guides: install MySQL, install MariaDB, install PostgreSQL, MySQL tuning, PostgreSQL tuning.

What about MariaDB?

MariaDB began as a MySQL fork and remains largely compatible for applications, though the two have diverged (JSON storage, authentication, optimizer features, replication). Debian packages MariaDB as its default “MySQL”. For WordPress and most PHP apps, MariaDB and MySQL are interchangeable. See MariaDB vs MySQL.

Recommendations by use case

Use case Pick
WordPress, WooCommerce, Magento, Drupal MySQL or MariaDB
New Django / Rails / Node.js / Go app PostgreSQL
Geographic data PostgreSQL + PostGIS
AI features with embeddings PostgreSQL + pgvector
Time-series metrics PostgreSQL + TimescaleDB
Team has deep MySQL experience MySQL
Mostly JSON documents but need SQL too PostgreSQL (jsonb)

Can you switch later?

Yes, but it’s work: SQL dialect differences, data types, and application queries need adjusting. Tools like pgloader migrate data from MySQL to PostgreSQL. ORMs (Django ORM, Prisma, Eloquent, SQLAlchemy) reduce the effort significantly.

Either database runs comfortably on a KVM VPS with SSD storage — start small, and scale RAM as your data grows.

  • MySQL
  • PostgreSQL
  • Databases