caching-strategies

name	caching-strategies
description	Use when: add caching with the right layer, key design, invalidation, and consistency trade-offs.

Goal: caching that speeds reads without serving wrong data.

Use for:

• reducing latency or load on expensive operations
• choosing where and how long to cache
• fixing stale or inconsistent cached data

Workflow:

1. Identify the read hot path worth caching.
2. Choose the layer: in-memory, distributed, CDN, or HTTP.
3. Design stable cache keys that capture all inputs.
4. Set TTLs by tolerance for staleness.
5. Define invalidation: on write, by tag, or by expiry.
6. Measure hit rate and verify correctness under updates.

Patterns:

• cache-aside (read-through) for most workloads
• write-through/write-behind when writes dominate
• tag or key-based invalidation on mutations
• stampede protection (locks, jitter) on hot keys

Rules:

• never cache user-specific or secret data in shared caches
• invalidate on the write that changes the source
• include every input that affects the result in the key
• prefer short TTLs over clever invalidation when unsure