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name: nestjs-caching description: Implement multi-level caching, invalidation patterns, and stampede protection in NestJS. Use when adding Redis caching layers, configuring cache-manager interceptors, implementing stale-while-revalidate, or preventing cache stampedes in NestJS services. metadata: triggers: files: - '/*.service.ts' - '/*.interceptor.ts' keywords: - CacheInterceptor - CacheTTL - Redis - stale-while-revalidate

Caching & Redis Standards

Priority: P1 (HIGH)

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 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 O(N) in production).
• Create: SADD post:1:tags cache:post:1
• Invalidate: Fetch tags from Set, then DEL 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 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 not shared across pods.