User opens the app. Show the nearest 10 coffee shops. Sounds simple until you realize ’nearest’ means computing distance against millions of locations in under 100ms.

Cache expires. 10,000 requests hit the database simultaneously. Your DB collapses. How request coalescing and probabilistic expiration prevent the stampede.

Why one cache isn’t enough. How to layer local, distributed, and CDN caches for maximum performance without losing your mind on consistency.

What happens when a popular cache key expires and thousands of requests hit your database at once. Three patterns to prevent the thundering herd.

There are only two hard things in computer science: cache invalidation and naming things. Here’s why invalidation is so tricky, and what actually works.

The four fundamental caching patterns every engineer should know. When to use cache-aside vs write-through vs write-behind vs read-through.