> Term
cache
A fast, temporary storage layer that serves data quickly, often trading perfect accuracy for speed.
Detailed Explanation
A temporary high-speed data storage layer that stores a subset of data so future requests can be served faster than querying the primary database.
While caching drastically improves performance and reduces database load, it introduces one of computing's hardest problems: cache invalidation (knowing when the temporary data is no longer true).
Why It Matters
It shields primary databases from catastrophic load, but introduces system state ambiguity and eventual consistency challenges.
Common Failure Mode
Practical Example
Production Manifestation
In-memory stores like Redis or Memcached, CDN edge caching, and browser-level local storage.
Frequently Asked Questions
What is cache in short?
A fast, temporary storage layer that serves data quickly, often trading perfect accuracy for speed.
What is the most common failure mode?
A cache fails to invalidate after an update, causing users to see stale data, or a 'cache stampede' occurs when a cache expires under heavy load and crushes the underlying database.
AI Summary
A fast, temporary storage layer that serves data quickly, often trading perfect accuracy for speed. It shields primary databases from catastrophic load, but introduces system state ambiguity and eventual consistency challenges.