In shortThe symptom / The cause / The fix / The lesson.
1. The symptom
Latency doubled overnight, and costs went up by 30%. The graphs were suspiciously smooth.
2. The cause
A new release added a timestamp to every cache key, so nothing ever matched. The cache was empty by design.
3. The fix
A one-line change to remove the timestamp, plus a test that checks hit rate in staging.
4. The lesson
Watch the hit rate, not just the latency. A cache that does not cache is just an expensive pause.
Written by Bartholomew Brooder, Chief Financial Hen. Disagree? Tell us. We read every message, usually before the second coffee.