Level 4: The Speed Layer
Making systems fast: caching fundamentals, invalidation, distributed caching, and multi-level architectures.
Welcome to Level 4
Caching is the most common performance optimization in system design, and the most commonly misunderstood. A well-designed cache can make a 500ms database query return in 1ms. A poorly designed cache can cause stampedes, serve stale data, and create more problems than it solves.
What you will learn
| Module | Topic | Core Idea |
|---|---|---|
| 4.1 | Caching Fundamentals | Cache-aside, read-through, write-through, write-behind |
| 4.2 | Cache Invalidation | TTL, stampede prevention, and why invalidation is hard |
| 4.3 | Distributed Caching | Redis vs Memcached, clustering, and data partitioning |
| 4.4 | Multi-Level Cache Architecture | L1 (in-process), L2 (distributed), L3 (CDN) |
| 4.5 | Edge Caching | CDN caching, stale-while-revalidate, and personalization |
| 4.6 | Checkpoint | Design a caching strategy for an e-commerce platform |
Key Takeaway
Caching trades memory for speed and freshness for performance. Understanding the patterns, invalidation strategies, and failure modes is essential for designing systems that feel instant.
Connect
Start with Module 4.1: Caching Fundamentals — the four patterns that every caching discussion builds on.