Memcache概念
- Memcache是一款高性能、分布式的内存对象缓存系统
-
类似数据库的存储系统
-
Memcache可以有效的分担数据库的负载
-
Memcache基于libvent事件处理实现无阻塞通信
memcached的数据底层
-
1.Memcached是key/value键值对的形式存储
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2.key的样子：key flags extime length
memcache安装部署
| 包名 | 作用 |
|---|---|
| memcached-1.5.7.tar.gz | memcached主程序 |
| libevent-2.1.8-stable.tar.gz | 依赖包 |
部署安装
tar -xf libevent-2.1.8-stable.tar.gz
cd libevent-2.1.8-stable
./configure --prefix=/usr/local/libevent
make &&make install
tar -xf memcached-1.5.7.tar.gz
cd memcached-1.5.7
./configure --prefix=/usr/local/memcached/ --with-libevent=/usr/local/libevent
make &&make install
Memcached启动参数
| 参数 | 参数作用 |
|---|---|
| -d | 启动一个守护进程 |
| -m | 分配给Memcached使用的内存数量 |
| -u | 运行Memcached的用户 |
| -I | 监听的服务器IP地址 |
| -p | 监听的端口 |
| -c | 最大运行的并发连接数 |
| -P | 设置保存Memcache的PID文件 |
启动第一个memcached
memcached -u root -l 192.168.4.51 -p 2222 -c 128 -m 10 -P my.pid -d #后台执行监听2222端口内存10M允许连接的客户端128指定PID文件
memcached常用命令
| 分类 | 命令 | 命令作用 |
|---|---|---|
| 新增 | set | 用于向缓存添加新的键值对 |
| 新增 | add | 当缓冲中不存在键时候则写入 |
| 修改 | replace | 当键值已经存在时候进行替换 |
| 修改 | append | 在已经有的结果上追加数据 |
| 修改 | prepend | 在已经有的数据前补充数据 |
| 特殊修改 | cas | 检查和更新，通常与gets一起使用 |
| 特殊修改 | lncr/decr | 增加/减少数值 |
| 查询 | get/gets | 获取数据/数据+版本号 |
连接memcached
简单的文本协议工具telnet，并非针对memcache使用，可以测试端口、网路是否通畅。
[root@ceph-manager memcached]# telnet 192.168.4.51 2222 #放肆的体验
Memcached的存储机制
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