TL;DR — Celebrity Tweet Thundering Herd

You run a social media platform with 200M DAU. The architecture uses a CDN for static content, Redis cluster for hot data caching (TTL-based), and PostgreSQL with read replicas for persistent storage. The cache-aside pattern is used: on cache miss, the application queries the database, writes the result to Redis, and returns it. Normal cache hit rate is 98% with 100K QPS. Key features: Viral content must be served without interruption. Cache must eventually reflect data updates (not serve stale data forever).