Introduction to PostgreSQL

Almost every application needs to store data that many users read and change at the same time, and that must not get lost. PostgreSQL is the open source relational database that many developers reach for first: it is free, it follows the SQL standard closely, it protects your data with transactions and constraints, and it grows from a laptop to large production systems.

This guide takes you from "what is a relational database?" to running PostgreSQL 18 in production. Every part is hands-on: you type the commands into psql and compare your output with the real output shown in the guide.

What You'll Learn

The guide has ten parts. Each one builds on the previous parts, but you can jump to the topic you need.

1. Database Fundamentals: tables, keys and relationships, ACID transactions, and what happens inside PostgreSQL when a query runs.
2. How to Install PostgreSQL 18 and psql: install on Ubuntu, Debian, RHEL, macOS, Windows or Docker (or only the psql client), connect, and create your first database and application role.
3. SQL Basics and CRUD Operations: SELECT, INSERT, UPDATE and DELETE, filtering, sorting, upserts and aggregates.
4. Database Design and Schema Modeling: primary and foreign keys, relationships, normalization and PostgreSQL schemas.
5. Data Types and Constraints: choose the right column types and let the database reject bad data.
6. Advanced Queries and Joins: joins, subqueries, CTEs, window functions and LATERAL.
7. Indexes and Query Performance: read EXPLAIN ANALYZE plans and pick the right index.
8. Transactions and Concurrency Control: isolation levels, MVCC, row locks, job queues and deadlocks.
9. Backup, Recovery, and Replication: pg_dump, pg_basebackup, point-in-time recovery and streaming replicas.
10. Production Best Practices and Operations: security, tuning, connection pooling, monitoring, high availability and upgrades.

Why PostgreSQL?

Reliability: PostgreSQL grew out of the POSTGRES project at the University of California, Berkeley, started in 1986, and has been developed in the open since 1996. Committed data survives crashes, thanks to its write-ahead log.

Standards compliance: PostgreSQL follows the SQL standard closely, so most of what you learn applies to other relational databases too.

Rich features: jsonb documents, arrays, full-text search, window functions, recursive queries, row-level security and logical replication are built in.

Extensibility: extensions add capabilities without switching databases, for example PostGIS for geographic data or pgvector for vector search.

Performance: a well-configured server handles busy transactional workloads and complex analytical queries, and scales reads with replicas.

No vendor lock-in: the PostgreSQL License is a permissive open source license. There are no paid editions, and every cloud provider offers managed PostgreSQL.

Which Version This Guide Uses

The examples use PostgreSQL 18, the current major version in October 2026. Where a feature is new in version 18 (such as uuidv7(), RETURNING old and new, B-tree skip scans or virtual generated columns), the guide says so, and almost everything else works on PostgreSQL 14 and later. PostgreSQL 19 is in release candidate testing, and almost everything here applies to it as well.

The outputs shown in psql blocks come from running the commands against PostgreSQL 18.6.

Prerequisites

To follow along, you need:

• basic comfort with a terminal;
• a computer running Linux, macOS or Windows, or Docker;
• a text editor for longer SQL scripts.

You do not need any database experience. If you have used a spreadsheet, you already understand rows and columns, and the guide explains everything else as it goes.

What This Guide Covers

The guide is written for developers and DevOps engineers who need to use PostgreSQL, not only study it. You will learn to:

• design databases that prevent common data problems;
• write queries that stay fast as data grows;
• protect data with roles, constraints and transactions;
• debug queries that return the wrong rows or run slowly;
• run PostgreSQL in production and keep it running;
• recover from failures without losing data.

The examples use realistic data (user accounts, blog posts, orders, bank transfers) rather than abstract tables. Start with Database Fundamentals, or jump to installing PostgreSQL if you already know the concepts.

Practice hands-on

Reinforce what you learn here with the interactive Database Indexing simulator, right in your browser with no setup required.