Caching & Redis Standards

Priority: P1 (OPERATIONAL)

Caching strategies and Redis integration patterns for high-performance NestJS applications.

Caching Strategy

• Layering: Use Multi-Level Caching for high-traffic read endpoints.
  • L1 (Local): In-Memory (Node.js heap). Ultra-fast, no network. Use lru-cache for config/static data.
  • L2 (Distributed): Redis. Shared across pods.
• Pattern: Implement Stale-While-Revalidate to avoid latency spikes during cache misses.

NestJS Implementation

• Library: Use cache-manager with cache-manager-redis-yet (recommended over cache-manager-redis-store for V4 stability).
• Interceptors: Use @UseInterceptors(CacheInterceptor) for simple GET responses.
  • Warning: Default key is the URL. Ensure consistent query param ordering or use custom key generators.

See implementation examples

Stampede Protection

• Jitter: Add random variance to TTLs to prevent simultaneous expiry across keys.
• Locking: One process recomputes while others wait or return stale data.

See implementation examples

Redis Data Structures

• Hash (HSET): Store objects (user profiles) with partial update support.
• Set (SADD): Unique collections with O(1) membership checks.
• Sorted Set (ZADD): Priority queues, leaderboards, rate-limiting windows.

Invalidation Patterns

• Tagging: Use Sets to group cache keys (avoid KEYS which is O(N) in production).
  • Create: SADD post:1:tags cache:post:1
  • Invalidate: Fetch tags from Set, then DEL the grouped keys.
• Event-Driven: Listen to domain events (UserUpdated) to trigger invalidation asynchronously.

Anti-Patterns

• No KEYS in production: Use SET-based tag grouping for cache invalidation; KEYS is O(N).
• No fixed TTLs on grouped caches: Add jitter (±10s) to prevent simultaneous stampede.
• No MemoryStorage for multi-pod: Use Redis store; in-memory cache is not shared across pods.