Redis Internals
Why a single-threaded in-memory store is so fast, which data structures it offers, and how persistence, replication and clustering work.
What Redis is
Redis (Remote Dictionary Server) is an in-memory data structure server. You do not just store strings; you store lists, sets and sorted sets and run operations on them on the server. Data lives in RAM, so a typical command answers in well under a millisecond.
Compared with a cache like Memcached (a simpler key to string store), Redis adds rich types, optional persistence, replication and clustering. See Caching for where it sits in an architecture.
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