deangrant Caching at Scale
Use this skill for application and edge caching strategy (beyond basic Cache-Control alone).
1. Pattern selection
| Workload | Prefer |
|---|---|
| Read-heavy general | Cache-aside |
| Always-warm mutable config/sessions | Write-through |
| Write-heavy analytics | Write-behind (accept crash loss) |
| Shared complex loaders | Read-through |
2. Stampede / miss storms
Singleflight or probabilistic early refresh on hot keys. Negative-cache misses with jitter. Warm hot keys on promote/traffic shift.
3. Invalidation
Not TTL-only for mutable data. Event-driven/CDC for critical freshness.
Tag-based invalidation when one write touches many keys. CDN: s-maxage,
Surrogate-Key purge. User-specific: private + Vary: Authorization.
HTTP GET: ETag/304 + optional stale-while-revalidate.
4. Quick checklist
- Pattern matches read/write profile.
- Stampede protection on hot keys.
- Explicit invalidation path (not only TTL).
- Tenant/user in cache keys where needed.
- CDN vs app-cache responsibilities clear.
See reference.md and examples.md.