Memcached通过在内存中开辟一块区域来维持一个大的hash表来加快页面访问速度，虽然和数据库是独立的，但是目前主要用来缓存数据库的数据。允许多个server通过网络形成一个大的hash，用户不必关心数据存放在哪，只调用相关接口就可。存放在内存的数据通过LRU算法进行淘汰出内存。同时可以通过删除和设置失效时间来淘汰存放在内存的数据-Memcached in memory by opening an area to maintain a large hash table to speed up page access speed, though, and databases are independent, but at present mainly used to cache database. Allows multiple server network to form a large hash, users do not care about the data stored in which only you can call the relevant interface. The data stored in the memory through the LRU algorithm is out of out of memory. At the same time can be deleted and set to expire time to phase out the data stored in the memory