Redis
3 engineering logs on Redis. Newest first.
- Negative caching: the misses cost more than the hits
Why a cache that only stores successes leaves the expensive path completely unprotected, how an attacker turns that into a denial of service with random keys, and why caching absence needs a different TTL than caching presence.
- Cache stampede: how one expired key takes down the database
Why TTL expiry is a synchronised event that sends every concurrent request to the origin at once, why the pileup amplifies itself while the recompute runs, and why jitter is the cheapest fix nobody applies.
- Scaling a distributed cache: Why consistent hashing is mandatory
Why modulo-based cache sharding fails in production and how consistent hashing with virtual nodes protects your database.