juniorCaching
What is a Cache Hit vs. a Cache Miss?
Updated Apr 28, 2026
Short answer
A hit is when data is found in the cache; a miss is when it's not and must be fetched from the source.
Deep explanation
Caching is essential for performance optimization. A hit is when data is found in the cache; a miss is when it's not and must be fetched from the source. By reducing the need to access slower storage layers (like HDDs or remote databases), systems can achieve much lower latency.
Real-world example
Storing the results of a complex database query in Redis.
Common mistakes
- Not setting a TTL, leading to the cache growing indefinitely or serving very old data.
Follow-up questions
- Is cache persistent?