Database Engineering

"The database is never just a detail. It is the center of gravity of every production system."

What You'll Master

This guide covers the full spectrum of database engineering — from choosing the right data model to tuning queries under production load. You will understand why PostgreSQL uses MVCC, how sharding decisions break apart at the seams, and what Instagram actually changed to serve 1 billion photos a day.

Companion reading for System Design Ch09 — Databases: SQL and Ch10 — Databases: NoSQL, which cover the selection layer. This guide goes deeper: internals, operations, and architecture.

The Learning Path

Work through the parts sequentially — each builds on concepts from the previous.

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Part 1 — Foundations

Storage engines, data models, indexes, and transactions. The non-negotiable bedrock every database engineer must own.

#	Chapter	Difficulty	~Time
01	The Database Landscape	Beginner	30 min
02	Data Modeling for Scale	Intermediate	35 min
03	Indexing Strategies	Intermediate	40 min
04	Transactions & Concurrency Control	Advanced	45 min

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Part 2 — Engine Deep Dives

Under the hood of PostgreSQL, MySQL, the major NoSQL families, and specialized engines for time-series, search, and vectors.

#	Chapter	Difficulty	~Time
05	PostgreSQL in Production	Intermediate	40 min
06	MySQL & Distributed SQL	Intermediate	35 min
07	NoSQL at Scale	Intermediate	45 min
08	Specialized Databases	Intermediate	50 min

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Part 3 — Scaling & Operations

How to keep databases alive, fast, and consistent when they grow beyond a single machine.

#	Chapter	Difficulty	~Time
09	Replication & High Availability	Advanced	50 min
10	Sharding & Partitioning	Advanced	45 min
11	Query Optimization & Performance	Advanced	50 min
12	Backup, Migration & Disaster Recovery	Intermediate	55 min

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Part 4 — Real-World Design

Full case studies from companies that solved hard database problems at scale. Specific numbers, specific decisions, specific regrets.

#	Chapter	Difficulty	~Time
13	Instagram: PostgreSQL at Scale	Advanced	30 min
14	Discord: Data Layer Evolution	Advanced	30 min
15	Uber: Geospatial Database Design	Advanced	30 min
16	Database Selection Framework	Intermediate	35 min

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Prerequisites

Before starting Part 1, you should be comfortable with:

• [ ] Basic SQL (SELECT, JOIN, GROUP BY)
• [ ] What a primary key and foreign key are
• [ ] General understanding of how a web application uses a database

You do not need to be a DBA. This guide teaches database internals from first principles.

If you want the big-picture view of database selection first, read System Design Ch09 and Ch10 before starting here.

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How to Use This Guide

1. Read Part 1 completely — indexes and transactions are referenced in every subsequent chapter
2. Run the SQL examples — theory without execution is incomplete; use a local PostgreSQL instance
3. Draw the diagrams — B-tree traversal, MVCC tuple chains, and replication topologies are learned by sketching
4. Attempt the practice questions — each chapter has three difficulty tiers
5. Return to case studies — Part 4 is most valuable after completing Parts 1–3

Total estimated time: ~11 hours across 16 chapters

$ cat handbook --sections
  database/
    part-1-foundations/    4 chapters  (~2.5 hrs)
    part-2-engines/        4 chapters  (~2.8 hrs)
    part-3-operations/     4 chapters  (~3.3 hrs)
    part-4-real-world/     4 chapters  (~2.1 hrs)