PostgreSQL and MySQL power the majority of web applications worldwide. Both are mature, reliable, and free. But they're built on different philosophies: PostgreSQL prioritizes correctness, extensibility, and SQL standards compliance. MySQL prioritizes simplicity, read performance, and ease of use. At Pillai Infotech, we use both — MySQL for our CMD Center (straightforward CRUD, PHP ecosystem), PostgreSQL for analytics-heavy projects with complex queries. Here's how to decide for your project.
📋 Table of Contents
Head-to-Head Comparison
| Factor | PostgreSQL 17 | MySQL 9.x |
|---|---|---|
| SQL compliance | Excellent (most compliant) | Good (some deviations) |
| ACID compliance | Full (all operations) | Full (InnoDB engine) |
| JSON support | JSONB (binary, indexable) | JSON (text-based, indexed since 8.0) |
| Full-text search | Built-in (tsvector, GIN index) | Built-in (FULLTEXT index) |
| Geospatial | PostGIS (industry standard) | Spatial extensions (basic) |
| Concurrency | MVCC (readers never block writers) | MVCC (InnoDB, improved in 8.0+) |
| Extensibility | Custom types, operators, index methods | Plugins and UDFs |
| Partitioning | Declarative (range, list, hash) | Range, list, hash, key |
| Replication | Streaming + logical replication | Built-in Group Replication, InnoDB Cluster |
| License | PostgreSQL License (permissive) | GPL v2 (Oracle-owned) |
Performance Benchmarks
Performance depends heavily on workload type. Neither database is universally faster.
| Workload | PostgreSQL | MySQL | Winner |
|---|---|---|---|
| Simple reads (PK lookup) | Fast | Slightly faster | MySQL (marginal) |
| Complex joins (5+ tables) | Excellent optimizer | Good but limited | PostgreSQL |
| Analytical queries (GROUP BY, window) | Strong (parallel query) | Adequate | PostgreSQL |
| Write-heavy (inserts) | Good (WAL-based) | Good (InnoDB buffer) | Comparable |
| JSON queries | JSONB with GIN index | JSON with functional index | PostgreSQL |
| High-concurrency reads | Excellent (MVCC) | Excellent (InnoDB) | Comparable |
The practical takeaway: If your workload is primarily simple CRUD with some joins (typical web app), both perform comparably. If you're doing complex analytical queries, window functions, CTEs, or JSON-heavy operations, PostgreSQL's query planner and optimizer consistently outperform MySQL.
JSON and Document Support
Both databases support JSON, but the implementations differ significantly:
-- PostgreSQL JSONB — binary storage, indexable, powerful operators
CREATE TABLE products (
id SERIAL PRIMARY KEY,
name TEXT NOT NULL,
attributes JSONB DEFAULT '{}'
);
-- GIN index for fast JSON queries
CREATE INDEX idx_products_attrs ON products USING GIN (attributes);
-- Query nested JSON efficiently
SELECT name, attributes->'specs'->>'weight' AS weight
FROM products
WHERE attributes @> '{"category": "electronics"}'
AND (attributes->'specs'->>'weight')::numeric < 500;
-- JSONB path queries (SQL/JSON standard)
SELECT name FROM products
WHERE attributes @? '$.tags[*] ? (@ == "wireless")';
-- MySQL JSON — text storage, functional indexes
CREATE TABLE products (
id INT AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(255) NOT NULL,
attributes JSON
);
-- Functional index on JSON path
CREATE INDEX idx_category ON products (
(CAST(attributes->>'$.category' AS CHAR(50)))
);
-- Query JSON
SELECT name, attributes->>'$.specs.weight' AS weight
FROM products
WHERE JSON_EXTRACT(attributes, '$.category') = 'electronics'
AND CAST(attributes->>'$.specs.weight' AS DECIMAL) < 500;
@>). MySQL stores JSON as text with internal optimization. If JSON querying is a core part of your application (not just storage), PostgreSQL has a significant advantage. For apps that use NoSQL-like patterns within SQL, PostgreSQL's JSONB can sometimes eliminate the need for a separate document database.
Advanced Features
PostgreSQL's feature set is significantly broader. Features that PostgreSQL has and MySQL doesn't (or does differently):
- CTEs (WITH RECURSIVE): Both support CTEs, but PostgreSQL's implementation is more optimized. MySQL added CTEs in 8.0 and they've improved significantly
- Window functions: Both support them, but PostgreSQL supports more frame types and has better optimization for complex window queries
- Custom types: PostgreSQL lets you define custom data types, operators, and index methods. This powers extensions like PostGIS, pgvector, and TimescaleDB
- LISTEN/NOTIFY: PostgreSQL has built-in pub/sub for real-time notifications. No equivalent in MySQL without polling or external tools
- Partial indexes: Index only rows that match a condition. Dramatically reduces index size for filtered queries
- UPSERT (ON CONFLICT): Both support it, PostgreSQL's syntax is more flexible with ON CONFLICT DO UPDATE
- Array and range types: Native array columns and range types (integer ranges, date ranges) with operators and indexing
Replication and High Availability
| HA Feature | PostgreSQL | MySQL |
|---|---|---|
| Primary-replica | Streaming replication (built-in) | Async/semi-sync replication (built-in) |
| Logical replication | Built-in (table-level, selective) | Binary log-based |
| Automatic failover | Patroni, pg_auto_failover | InnoDB Cluster, Group Replication |
| Multi-primary | BDR (third-party), Citus | Group Replication (multi-primary mode) |
| Connection pooling | PgBouncer (external, essential) | ProxySQL / MySQL Router |
MySQL's InnoDB Cluster and Group Replication provide a more integrated HA solution out of the box. PostgreSQL requires assembling components (Patroni + PgBouncer + etcd), but this composability gives you more control. For managed services (RDS, Cloud SQL, Supabase), HA is handled for you regardless of which database you choose. See our database scaling guide for more on replication strategies.
Ecosystem and Hosting
| Ecosystem | PostgreSQL | MySQL |
|---|---|---|
| Managed hosting | AWS RDS, Cloud SQL, Supabase, Neon, Crunchy Bridge | AWS RDS/Aurora, Cloud SQL, PlanetScale, Vitess |
| Key extensions | PostGIS, pgvector, TimescaleDB, Citus | Vitess (sharding), ProxySQL |
| ORM support | Excellent (Prisma, SQLAlchemy, Hibernate, etc.) | Excellent (all major ORMs) |
| Shared hosting | Rare on shared hosts | Available everywhere (cPanel default) |
| WordPress / CMS | Not supported by WP | Default for WordPress, Drupal |
| Vector search (AI) | pgvector (mature, integrated) | HeatWave Vector Store (limited) |
PostgreSQL's extension ecosystem is a major differentiator. pgvector for AI/ML embeddings, PostGIS for geospatial, TimescaleDB for time-series, and Citus for distributed queries — all run within PostgreSQL itself, no separate databases needed.
Decision Guide
| Scenario | Choose | Why |
|---|---|---|
| WordPress or PHP CMS | MySQL | WordPress requires MySQL/MariaDB |
| Complex analytics + OLAP queries | PostgreSQL | Superior query planner, parallel query, CTEs |
| Simple CRUD web app | Either | Both handle this equally well |
| Geospatial / mapping | PostgreSQL | PostGIS is the industry standard |
| AI/ML vector search | PostgreSQL | pgvector is mature and well-integrated |
| Shared hosting (cPanel) | MySQL | Universally available on shared hosts |
| Heavy JSON/document workload | PostgreSQL | JSONB with GIN indexing |
| Global-scale sharding | MySQL | Vitess (YouTube-scale) and PlanetScale |
| Supabase / modern BaaS | PostgreSQL | Supabase, Railway, Neon are all Postgres |
Frequently Asked Questions
Is PostgreSQL faster than MySQL?
For complex queries with multiple joins, CTEs, and window functions — yes, PostgreSQL's query planner is more sophisticated. For simple key-value reads, MySQL is marginally faster. For typical web app workloads, the difference is negligible.
Should I use MariaDB instead of MySQL?
MariaDB forked from MySQL and maintains compatibility. It's a good choice if Oracle's ownership concerns you. However, MySQL 9.x and MariaDB have diverged in some features. For most projects, both work fine — choose based on hosting availability.
Can PostgreSQL replace MongoDB?
For many use cases, yes. PostgreSQL's JSONB support with GIN indexing handles document-style workloads well while giving you ACID transactions and SQL joins. For pure document workloads at massive scale, MongoDB still has edge cases where it excels.
Which is easier to manage?
MySQL is simpler to set up and has less configuration overhead. PostgreSQL requires more tuning (shared_buffers, work_mem, connection pooling with PgBouncer) but gives you more control. With managed services (RDS, Cloud SQL), both are equally easy.
Is PostgreSQL gaining market share over MySQL?
Yes. PostgreSQL has been the fastest-growing database engine for several years. The rise of Supabase, pgvector for AI, and PostGIS for geospatial have accelerated adoption. But MySQL remains dominant in volume — there are more MySQL databases running than PostgreSQL, largely due to WordPress and legacy applications.
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