Database Internals - Reading Notes

3 minute read • February 4, 2026

This is a collection of my notes on Database Internals by Alex Petrov. The book provides a deep dive into how database management systems work under the hood, covering storage engines, distributed systems, and the algorithms that power modern databases.

Chapter Notes

Part I - Storage Engines

Part II - Distributed Systems

Motivation

These notes are intended as a reference and are not meant as a substitute for the original text. I’ve been enjoying the book so far, and I highly recommend that anyone interested in the topic read it themselves. I found Timilehin Adeniran’s notes on Designing Data-Intensive Applications extremely helpful while reading that book, so I thought I’d try to do the same here.

When learning about complex topics, I take notes twice - once with pen and paper and once more by keyboard a few days later for the sake of spaced repetition. These posts represent my second pass at note-taking and benefit from the ability to link to external documents, embed diagrams and videos, etc. Plus, nobody has to try to read my handwriting.

Database systems are fundamental to modern software infrastructure, yet their inner workings often remain opaque to application developers. Understanding how databases store, index, and retrieve data can help engineers make better architectural decisions, optimize query performance, and debug production issues.

AI Usage

I do not use AI of any form while writing these notes. I do however use GitHub Copilot to review my notes and check for typos, grammatical issues, etc. The agent I use for reviewing these articles is defined here.

Additional Resources

Attribution

Database Internals by Alex Petrov (O’Reilly). Copyright 2019 Oleksander Petrov, 978-1-492-04034-7

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