Caching

Serving reads in under a millisecond and shielding the database from the load: sharding, eviction, hot keys, and stampede protection.

Explainers

• Design a Distributed Cache — Start with one box in front of the database; end with a sharded, replicated cache that survives a celebrity key pulling 300k requests a second. Consistent hashing, cache-aside, eviction, and the hot-key problem — detection, absorption, and stampede protection — drawn and computed.