intermediate · datastores

Is 90% a Good Hit Rate?

Your cache hit rate is 90%. Is that good?

Practical scenario

A dashboard shows a steady 90% hit rate on the product cache. Someone proposes it as evidence that caching is working well and the team should move on.

What it tests

  • Whether the candidate refuses a context-free number
  • Understanding that miss cost matters more than miss count
  • Awareness of what a hit rate cannot tell you

Lessons behind this question