Cache Doesn't Make Your System Faster. It Just Moves the Complexity Somewhere Else.
There's a dangerous misconception in software engineering: that adding a cache is a performance solution. It isn't. It's a trade-off – one that swaps database load for a new set of problems around consistency, failure modes, and operational complexity.
Every caching decision ultimately comes down to one question: who is responsible for writing to the cache, and when does that write happen?
Answer that question differently and you get six distinct patterns. Each one makes sense in a specific context and falls apart in others. Here's a map of all six – not just what they are, but why you'd reach for each one.
