Missing cache TTL / unbounded cache

What it is

A cache is written without a TTL or eviction policy, or a hot read path has no cache in front of it at all.

Why it matters

An unbounded cache grows until the process runs out of memory, and its entries can serve stale data indefinitely. The opposite case — no cache on a repeated read — pays the full query cost on every request for data that rarely changes.

How to fix it

Set an explicit TTL and a size bound with an eviction policy on every cache. For uncached hot reads, add a short TTL first and only reach for explicit invalidation once you know the access pattern.