System Design for Developers
Reasoning about load, state, and failure before you write the code
Almost every scaling problem is a decision made early, cheaply and without evidence, so design is the discipline of forcing load, state and failure into the open and writing down why.
Design is not drawing boxes. It is deciding, in order, what load the system has to absorb, where state lives and what consistency it needs, and how the thing behaves when a dependency is gone, then recording the constraint that forced each answer and the signal that would reverse it. This book works through that order using the decisions that actually cost money later: data model, service boundaries, caching, queues and backpressure, timeouts and idempotency, observability, capacity, and how to migrate a system that cannot stop running.
What it makes operable
-
01
Start from a load model instead of a box diagram
-
02
Choose state, consistency and a data model you can still live with at scale
-
03
Make timeouts, retries, idempotency and backpressure explicit decisions
-
04
Write a decision record that names the constraint and the reversal signal
Contents
13 of 13 published
Every chapter is free to read in the browser, cites its own sources, and stands on its own if you came for one decision rather than the whole argument.
- 01 Start From the Load, Not the Diagram Shape, peak and growth of traffic, established before a single box is drawn. 11 min
- 02 State Is the Hard Part Why stateless services are easy and the data underneath them is not. 10 min
- 03 Consistency You Can Explain to the Business Choosing a guarantee, then describing it in a sentence non-engineers accept. 10 min
- 04 Choosing a Data Model You Can Live With Access patterns first; the choice of store is a consequence of them. 11 min
- 05 Where to Put the Boundary Between Services Transaction scope, ownership and deploy cadence, not domain diagrams. 10 min
- 06 Caching: Correctness First Invalidation, staleness contracts, and what a cache is allowed to serve. 10 min
- 07 Queues, Backpressure, and Fair Scheduling What the system does when work arrives faster than it can be finished. 11 min
- 08 Timeouts, Retries, Idempotency The three settings that decide whether a partial failure corrupts data. 11 min
- 09 Failure Domains and the Blast Radius You Chose How many customers one failure is allowed to reach, decided on purpose. 11 min
- 10 Observability as a Design Input Deciding what you will need to see while the design is still cheap to change. 11 min
- 11 Capacity, Cost, and the Bill Turning a load model into a number the business can plan against. 10 min
- 12 Migrating a Running System Dual writes, backfills, cutovers, and the rollback you keep in reserve. 11 min
- 13 Writing the Decision Record The constraint that forced the choice and the signal that would reverse it. 11 min
Evidence · 2 sources
Third-party sources behind the book's premise. Every figure in them belongs to the party that published it and is attributed to them in the text.
