最近在面试，很多公司都有要求使用过 Redis ，之前没有用过，既然很多公司都要求会，自然是有原因的。本文试着简单学习下 Redis ，并了解下它与 MemoryCache 有什么区别的（之前在 LPS 缓存是用的 MemoryCache ）。
定义
看下官网的说明，
Redis is an open source (BSD licensed), in-memory data structure store, used as a database, cache and message broker. It supports data structures such as strings, hashes, lists, sets, sorted sets with range queries, bitmaps, hyperloglogs, geospatial indexes with radius queries and streams. Redis has built-in replication, Lua scripting, LRU eviction, transactions and different levels of on-disk persistence, and provides high availability via Redis Sentinel and automatic partitioning with Redis Cluster.