caching

This skill should be used when the user asks about a "caching strategy", "cache invalidation", "what to cache", "read-through vs write-through vs write-back", "cache eviction" (LRU/LFU/TTL), "Redis vs Memcached", "stale reads", or hits "thundering herd", "cache stampede", "cache penetration", or "hot key" problems, or is choosing a Redis maxmemory eviction policy (allkeys-lru, volatile-lru, noeviction) vs TTL expiry for sessions or other cached state. Use it whenever a design is read-heavy or a datastore is overloaded by reads, even if the user doesn't say "cache".