MySQL vs PostgreSQL: Which Database to Choose? (2026)

import ComparisonTable from ’../../components/ComparisonTable.astro’;

MySQL and PostgreSQL are the two most popular open-source relational databases. MySQL dominated web development for two decades (the M in LAMP stack); PostgreSQL has surged in adoption as applications require more sophisticated database capabilities.

Quick Verdict

Choose PostgreSQL if: You’re starting a new project, need JSON/JSONB capabilities, require advanced data types, or want a more standards-compliant SQL implementation.

Choose MySQL if: You’re integrating with an existing MySQL ecosystem, using managed services like Amazon Aurora MySQL, or your team has deep MySQL expertise and simpler requirements.

Feature Comparison

JSON Handling

MySQL JSON:

CREATE TABLE products (
  id INT PRIMARY KEY,
  name VARCHAR(255),
  metadata JSON
);

INSERT INTO products VALUES (
  1, 
  'Widget Pro',
  '{"color": "blue", "weight": 1.5, "tags": ["sale", "featured"]}'
);

-- Query JSON field (no index on JSON fields by default)
SELECT name, metadata->>'$.color' AS color
FROM products
WHERE JSON_CONTAINS(metadata, '"sale"', '$.tags');

-- JSON index requires generated column
ALTER TABLE products 
ADD COLUMN color VARCHAR(50) 
GENERATED ALWAYS AS (metadata->>'$.color') STORED;

CREATE INDEX idx_color ON products(color);

PostgreSQL JSONB:

CREATE TABLE products (
  id SERIAL PRIMARY KEY,
  name VARCHAR(255),
  metadata JSONB  -- Binary JSON, directly indexable
);

INSERT INTO products VALUES (
  1,
  'Widget Pro',
  '{"color": "blue", "weight": 1.5, "tags": ["sale", "featured"]}'
);

-- Create GIN index on entire JSONB column
CREATE INDEX idx_metadata ON products USING GIN(metadata);

-- Query with index (fast even on large tables)
SELECT name, metadata->>'color' AS color
FROM products
WHERE metadata @> '{"tags": ["sale"]}';

-- Extract and aggregate JSON fields
SELECT 
  metadata->>'color' AS color,
  COUNT(*) AS product_count,
  AVG((metadata->>'weight')::float) AS avg_weight
FROM products
GROUP BY metadata->>'color';

-- Update a nested JSON field
UPDATE products
SET metadata = metadata || '{"discount": 0.1}'
WHERE id = 1;

PostgreSQL’s JSONB is fundamentally more powerful — indexable, directly query-able, and with richer operators.

Advanced Data Types

PostgreSQL-exclusive types:

-- Arrays
CREATE TABLE users (
  id SERIAL PRIMARY KEY,
  name TEXT,
  tags TEXT[],          -- Array type
  permissions INT[]
);

INSERT INTO users VALUES (1, 'Alice', ARRAY['admin', 'user'], ARRAY[1, 2, 3]);

-- Query arrays
SELECT * FROM users WHERE 'admin' = ANY(tags);
SELECT * FROM users WHERE tags @> ARRAY['admin', 'user'];

-- Ranges
CREATE TABLE reservations (
  id SERIAL PRIMARY KEY,
  room_id INT,
  reserved_period TSRANGE  -- Timestamp range
);

INSERT INTO reservations VALUES (1, 101, '[2026-02-10 14:00, 2026-02-10 16:00)');

-- Find overlapping reservations (conflict detection)
SELECT * FROM reservations
WHERE room_id = 101 
  AND reserved_period && '[2026-02-10 15:00, 2026-02-10 17:00)';

-- UUID type
CREATE TABLE sessions (
  id UUID DEFAULT gen_random_uuid() PRIMARY KEY,
  user_id INT,
  created_at TIMESTAMPTZ DEFAULT NOW()
);

-- Network address types
CREATE TABLE servers (
  id SERIAL PRIMARY KEY,
  name TEXT,
  ip_address INET,
  mac_address MACADDR
);

-- Geometric types (PostGIS extends this further)
CREATE TABLE locations (
  id SERIAL PRIMARY KEY,
  name TEXT,
  position POINT,
  area POLYGON
);

Full-Text Search

MySQL full-text search:

CREATE TABLE articles (
  id INT PRIMARY KEY,
  title VARCHAR(255),
  body TEXT,
  FULLTEXT INDEX idx_fulltext (title, body)
);

-- Basic full-text search
SELECT *, MATCH(title, body) AGAINST ('postgresql database' IN NATURAL LANGUAGE MODE) AS score
FROM articles
WHERE MATCH(title, body) AGAINST ('postgresql database' IN NATURAL LANGUAGE MODE)
ORDER BY score DESC;

PostgreSQL full-text search:

CREATE TABLE articles (
  id SERIAL PRIMARY KEY,
  title TEXT,
  body TEXT,
  -- Store pre-computed tsvector for performance
  search_vector TSVECTOR GENERATED ALWAYS AS (
    setweight(to_tsvector('english', coalesce(title, '')), 'A') ||
    setweight(to_tsvector('english', coalesce(body, '')), 'B')
  ) STORED
);

CREATE INDEX idx_search ON articles USING GIN(search_vector);

-- Full-text search with ranking
SELECT 
  id,
  title,
  ts_rank(search_vector, query) AS rank,
  ts_headline('english', body, query) AS excerpt
FROM articles, 
  to_tsquery('english', 'postgresql & database') AS query
WHERE search_vector @@ query
ORDER BY rank DESC
LIMIT 10;

PostgreSQL’s FTS supports stemming, dictionaries, multiple languages, and relevance ranking out of the box.

Performance: Write-Heavy vs Read-Heavy

MySQL read performance: MySQL’s query cache (deprecated in 8.0) and simpler architecture traditionally made it faster for simple read queries. For high-concurrency read workloads, MySQL and PostgreSQL perform comparably.

PostgreSQL write performance: PostgreSQL’s MVCC implementation handles concurrent writes better, especially for complex transactions:

-- PostgreSQL handles this efficiently with MVCC
-- Multiple concurrent transactions don't block each other on reads

-- Transaction isolation levels
SET TRANSACTION ISOLATION LEVEL READ COMMITTED;  -- Default
SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;    -- Strongest

-- SKIP LOCKED — efficient queue processing
SELECT id, payload 
FROM job_queue
WHERE status = 'pending'
ORDER BY created_at
LIMIT 1
FOR UPDATE SKIP LOCKED;

Extensions (PostgreSQL’s Killer Feature)

-- pgvector: AI/ML vector similarity search
CREATE EXTENSION vector;

CREATE TABLE embeddings (
  id SERIAL PRIMARY KEY,
  content TEXT,
  embedding vector(1536)  -- OpenAI embedding size
);

-- Find most similar documents
SELECT content, embedding <-> '[0.1, 0.2, ...]' AS distance
FROM embeddings
ORDER BY distance
LIMIT 5;

-- PostGIS: Geospatial queries
CREATE EXTENSION postgis;

SELECT 
  name,
  ST_Distance(location, ST_Point(-73.9857, 40.7484)::geography) AS distance_meters
FROM restaurants
WHERE ST_DWithin(
  location, 
  ST_Point(-73.9857, 40.7484)::geography, 
  1000  -- 1km radius
)
ORDER BY distance_meters;

-- TimescaleDB: Time-series data
CREATE EXTENSION timescaledb;

SELECT create_hypertable('metrics', 'time');

-- Automatic partitioning by time — queries 10-100x faster
SELECT time_bucket('5 minutes', time) AS bucket,
       AVG(cpu_usage) AS avg_cpu
FROM metrics
WHERE time > NOW() - INTERVAL '1 hour'
GROUP BY bucket
ORDER BY bucket;

No MySQL equivalent exists for pgvector or PostGIS integration depth.

Replication and High Availability

MySQL replication:

-- Simple source-replica setup
-- On replica:
CHANGE REPLICATION SOURCE TO
  SOURCE_HOST='primary.db.example.com',
  SOURCE_USER='replication',
  SOURCE_PASSWORD='password',
  SOURCE_LOG_FILE='mysql-bin.000001',
  SOURCE_LOG_POS=4;

START REPLICA;
SHOW REPLICA STATUS\G

PostgreSQL streaming replication:

# postgresql.conf on primary
wal_level = replica
max_wal_senders = 3
wal_keep_size = 100MB

# pg_hba.conf
host replication replication_user replica_ip/32 md5

# On replica
pg_basebackup -h primary -U replication_user -D /var/lib/postgresql/data -P

Both support logical replication for selective table replication and cross-version replication.

Migration from MySQL to PostgreSQL

# Using pgloader for migration
# pgloader mysql://user:pass@mysql_host/mydb postgresql://user:pass@pg_host/mydb

# Manual migration considerations:
# 1. AUTO_INCREMENT → SERIAL or IDENTITY
# 2. TINYINT(1) → BOOLEAN
# 3. DATETIME → TIMESTAMP WITH TIME ZONE
# 4. ENUM → PostgreSQL ENUM or CHECK constraint
# 5. Backtick identifiers → double quotes
# 6. MySQL-specific functions → PostgreSQL equivalents

Bottom Line

PostgreSQL is the better database for new projects — superior JSON handling, richer type system, powerful extension ecosystem (especially pgvector for AI applications), and stricter SQL standards compliance. MySQL remains a solid choice for teams with existing infrastructure and simpler requirements. The managed database landscape (Supabase for PostgreSQL, Amazon Aurora for both) makes operational concerns less relevant. Choose PostgreSQL for new development.