redis 是一个高性能的key-value数据库。 redis的出现，很大程度补偿了memcached这类keyvalue存储的不足，在部 分场合可以对关系数据库起到很好的补充作用。-redis is a high performance key-value database. redis appearance to a large extent compensated for the lack memcached such keyvalue stored in some relational database where you can play a very good supplement.