Redis的简单使用和介绍 linux(centos 5.4) redis install
Redis除了作为存储之外还提供了一些其它方面的功能，比如聚合计算、pubsub、scripting等，对于此类功能需要了解其实现原理，清楚
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。它提供了Python，Ruby，Erlang，PHP,Java客户端，使用很方便。
Redis使用单线程的IO复用模型，自己封装了一个简单的AeEvent事件处理框架，主要实现了epoll、kqueue和select，对于单纯只有IO操作来说，，单线程可以将速度优势发挥到最大，但是Redis也提供了一些简单的计算功能，比如排序、聚合等，对于这些操作，单线程模型实际会严重影响整体吞吐量，CPU计算过程中，整个IO调度都是被阻塞住的。
Redis除了作为存储之外还提供了一些其它方面的功能，比如聚合计算、pubsub、scripting等，对于此类功能需要了解其实现原理，清楚地了解到它的局限性后，才能正确的使用，比如pubsub功能，这个实际是没有任何持久化支持的，消费方连接闪断或重连之间过来的消息是会全部丢失的，又比如聚合计算和scripting等功能受Redis单线程模型所限，是不可能达到很高的吞吐量的，需要谨慎使用。
本例子Linux采用的CentOS5.4
下面来介绍一下redis的安装
make完后 redis-2.0.4目录下会出现编译后的redis服务程序redis-server,还有用于测试的客户端程序redis-cli
安装成功启动服务
./redis-server
也可以通过启动参数告诉redis使用指定配置文件使用下面命令启动
./redis-server redis.conf
redis.conf是一个默认的配置文件。我们可以根据需要使用自己的配置文件。
启动redis服务进程后，就可以使用测试客户端程序redis-cli和redis服务交互了
注意启动的时候，会出现
WARNING overcommit_memory is set to 0!Background save may fail under
low memory condition. To fix this issue add'vm.overcommit_memory = 1' to /etc/sysctl.conf and
[6020] 10 Aug 20:58:21 * The server is nowready to accept connections on port 6379
[6020] 10 Aug 20:58:21 - 0 clientsconnected (0 slaves), 533432 bytes in use
[6020] 10 Aug 20:58:30 - 0 clientsconnected (0 slaves), 533432 bytes in use
由于默认配置是连接到本机的
这时候你要修改配置文件的ip地址连接你服务器啊
还有就是执行：sysctl vm.overcommit_memory=1
然后再启动服务就可以了
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