PostgreSQL

Learn when and how to leverage PostgreSQL in system design interviews

Intro

If you only have time to learn one database for system design interviews, make it PostgreSQL. Not only is PostgreSQL the most popular relational database in the world, but it's also consistently ranked as the most loved database by developers in the StackOverflow Developer Survey. Its combination of reliability, advanced features, and active community make it an excellent choice for both real-world applications and system design interviews. In fact, PostgreSQL is what powers this very website!

PostgreSQL (often called "Postgres") is an open-source relational database that combines rock-solid reliability with advanced features like full-text search, JSON support, and complex transactions. While newer databases often specialize in specific use cases, PostgreSQL remains the "Swiss Army knife" of databases, capable of handling everything from simple CRUD operations to complex analytical queries.

In this deep dive, we'll explore PostgreSQL from a system design interview perspective. We'll start with the fundamentals and progressively dive into more advanced topics like query optimization, scalability, and concurrency control before finally discussing some common interview topics.

Let's get after it.

Basic Concepts

Before diving into PostgreSQL-specific features, let's review how SQL databases organize data. These core concepts apply to any SQL database, not just PostgreSQL but are a necessary foundation that we will build on throughout this deep dive.

Already comfortable with SQL database basics? Feel free to skip ahead. But if you have time, I'd recommend reviewing this section - having a deep understanding of these fundamentals will help you confidently explain your design decisions in interviews.

Relational Database Principles

At its core, PostgreSQL stores data in tables (also called relations). Think of a table like a spreadsheet with rows and columns. Each column has a specific data type (like text, numbers, or dates), and each row represents one complete record.