PostgreSQL

Pronunciation: POHST-gres-kyoo-EL

Updated October 3, 20262 min read

In short

PostgreSQL is a free, open-source relational database known for reliability, strict standards support and extensions, and widely used for web applications.

What is PostgreSQL?

PostgreSQL, often just called Postgres, grew out of the POSTGRES research project at the University of California, Berkeley, which began in 1986. It is a relational database: data lives in tables with rows and columns, and you read and change it with SQL. It is developed by a global community and released under a permissive license, so anyone can use it for free, including in commercial products.

Postgres is known for doing things correctly. Transactions follow the ACID rules, so a group of changes either all happen or none do, and multiversion concurrency control (MVCC) lets many users read and write at the same time without blocking each other. It supports advanced SQL features such as window functions, common table expressions and many index types.

It is also unusually extensible. Columns can hold JSON in a binary format called JSONB that can be indexed and queried, so one database can serve both relational and document-style data. Extensions add whole new abilities: PostGIS for maps and geography, pgvector for AI embeddings, and full-text search is built in.

A common misconception is that PostgreSQL is only for very large or complex projects. It runs just as well behind a small website, and most cloud providers offer it as a managed service. Compared with MySQL, it is usually described as stricter and richer in features, while both are mature, fast and widely supported.

Key takeaways

PostgreSQL is a free, open-source relational database that uses SQL.
Transactions are ACID, and MVCC lets readers and writers work at the same time.
JSONB columns let it store and index document-style data.
Extensions such as PostGIS and pgvector add new capabilities.
It is offered as a managed service by most cloud providers.

Example

A table with a JSONB columnsql

CREATE TABLE products (
  id    SERIAL PRIMARY KEY,
  name  TEXT NOT NULL,
  price NUMERIC(10, 2) NOT NULL,
  attrs JSONB              -- flexible, document-style data
);

INSERT INTO products (name, price, attrs)
VALUES ('Desk lamp', 39.90, '{"color": "black", "watts": 8}');

-- Query inside the JSON
SELECT name FROM products WHERE attrs->>'color' = 'black';

Readers ask

Is PostgreSQL free?

Yes. It is released under the PostgreSQL License, a permissive open-source license, so you can use, change and ship it, also in commercial software, without paying.

What is the difference between PostgreSQL and MySQL?

Both are open-source relational databases. PostgreSQL is usually seen as stricter about standards and richer in advanced features and extensions, while MySQL is known for simplicity and its long history in web hosting. Either is a solid choice for most applications.

Can PostgreSQL store JSON?

Yes. The JSONB type stores JSON in a binary form that can be indexed and queried with operators, so PostgreSQL can handle many document-database use cases.