YepAPI/skills

Caching Strategy

Rules

• Cache at every layer: browser (Cache-Control), CDN (edge), application (Redis), database (query cache)
• Use stale-while-revalidate for content that can be slightly stale — serve fast, refresh in background
• Cache-Control headers: public, max-age=31536000, immutable for hashed static assets; public, s-maxage=60, stale-while-revalidate=300 for dynamic pages
• Redis caching: serialize to JSON, set TTL on every key, use namespaced keys (cache:users:123)
• React Query / TanStack Query: set staleTime (how long data is fresh) and gcTime (how long to keep in memory)
• Invalidate on write — when data changes, delete or update the cache entry immediately
• Use cache-aside pattern: check cache first, fetch from source on miss, write to cache
• For Next.js: leverage ISR (revalidate), unstable_cache, and fetch cache for server components
• Tag-based invalidation: tag cached entries by entity type, invalidate all entries for a tag on mutation

Patterns

// Cache-aside with Redis
async function getCachedUser(id: string) {
  const cached = await redis.get(`user:${id}`);
  if (cached) return JSON.parse(cached);
  const user = await db.user.findUnique({ where: { id } });
  await redis.set(`user:${id}`, JSON.stringify(user), "EX", 3600);
  return user;
}

Avoid

• Caching without TTL — stale data will persist indefinitely
• Caching user-specific data in shared CDN cache — use private or Vary headers
• Cache stampede: use locking or stale-while-revalidate to prevent thundering herd
• Caching error responses — only cache successful results