站长资讯网1、读写分离原理：
读写分离就是在主服务器上修改，数据会同步到从服务器，从服务器只能提供读取数据，不能写入，实现备份的同时也实现了数据库性能的优化，以及提升了服务器安全。
安装环境：
| linux环境 | centos7.3 |
| 192.168.2.201 | master主数据库 |
| 192.168.2.202 | slave从数据库 |
| 192.168.2.203 | mysql-proxy中间件 |
2、mysql的读写分离是在mysql主从复制的基础上的，所以我们先要搭建mysql的主从复制环境，之前的博客已经写到，这里不再多赘述。mysql的主从复制
下面我们在192.162.2.203机器上操作：
安装依赖：
yum install -y gcc* gcc-c++* autoconf* automake* zlib* libxml* ncurses-devel* libmcrypt* libtool* flex* pkgconfig* libevent* glib* readline-devel*
MySQL-Proxy的读写分离主要是通过rw-splitting.lua脚本实现的，因此需要安装lua。
wget http://www.lua.org/ftp/lua-5.3.4.tar.gz tar xf lua-5.3.4.tar.gz cd lua-5.3.4 vi src/Makefile #替换成下面的配置内容，删除原有的 CFLAGS= -O2 -Wall -fPIC -Wextra -DLUA_COMPAT_5_2 $(SYSCFLAGS) $(MYCFLAGS) make linux make install
3、下载myqsl-proxy中间件安装包，解压设置属组权限。
wget https://downloads.mysql.com/archives/get/file/mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit.tar.gz tar xf mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit.tar.gz -C /usr/local cd /usr/local/ mv mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit /usr/local/mysql-proxy useradd mysql-proxy chown -R mysql-proxy.mysql-proxy mysql-proxy* cd /usr/local/mysql-proxy #创建存放lua的脚本和日志的两个目录 mkdir lua mkdir logs #复制读写分离配置文件 cd /usr/local/mysql-proxy/lua cp share/doc/mysql-proxy/rw-splitting.lua . #修改rw-splitting.lua配置内容 proxy.global.config.rwsplit = { min_idle_connections = 1, //默认为4 max_idle_connections = 1, //默认为8 is_debug = false } #创建admin.lua脚本，不使用自带的admin-sql.lua脚本 vim admin.lua #添加一下内容 --[[ $%BEGINLICENSE%$ Copyright (c) 2007, 2012, Oracle and/or its affiliates. All rights reserved. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA $%ENDLICENSE%$ --]] function set_error(errmsg) proxy.response = { type = proxy.MYSQLD_PACKET_ERR, errmsg = errmsg or "error" } end function read_query(packet) if packet:byte() ~= proxy.COM_QUERY then set_error("[admin] we only handle text-based queries (COM_QUERY)") return proxy.PROXY_SEND_RESULT end local query = packet:sub(2) local rows = { } local fields = { } if query:lower() == "select * from backends" then fields = { { name = "backend_ndx", type = proxy.MYSQL_TYPE_LONG }, { name = "address", type = proxy.MYSQL_TYPE_STRING }, { name = "state", type = proxy.MYSQL_TYPE_STRING }, { name = "type", type = proxy.MYSQL_TYPE_STRING }, { name = "uuid", type = proxy.MYSQL_TYPE_STRING }, { name = "connected_clients", type = proxy.MYSQL_TYPE_LONG }, } for i = 1, #proxy.global.backends do local states = { "unknown", "up", "down" } local types = { "unknown", "rw", "ro" } local b = proxy.global.backends[i] rows[#rows + 1] = { i, b.dst.name, -- configured backend address states[b.state + 1], -- the C-id is pushed down starting at 0 types[b.type + 1], -- the C-id is pushed down starting at 0 b.uuid, -- the MySQL Server's UUID if it is managed b.connected_clients -- currently connected clients } end elseif query:lower() == "select * from help" then fields = { { name = "command", type = proxy.MYSQL_TYPE_STRING }, { name = "description", type = proxy.MYSQL_TYPE_STRING }, } rows[#rows + 1] = { "SELECT * FROM help", "shows this help" } rows[#rows + 1] = { "SELECT * FROM backends", "lists the backends and their state" } else set_error("use 'SELECT * FROM help' to see the supported commands") return proxy.PROXY_SEND_RESULT end proxy.response = { type = proxy.MYSQLD_PACKET_OK, resultset = { fields = fields, rows = rows } } return proxy.PROXY_SEND_RESULT end
4、创建mysql-proxy启动时所需要的配置文件
vi /etc/mysql-proxy.cnf #创建配置文件 [mysql-proxy] user=root admin-username=wyl admin-password=1234 proxy-address=192.168.2.203:4040 proxy-read-only-backend-addresses=192.168.2.202:3306 proxy-backend-addresses=192.168.2.201:3306 proxy-lua-script=/usr/local/mysql-proxy/lua/rw-splitting.lua admin-lua-script=/usr/local/mysql-proxy/lua/admin.lua log-file=/usr/local/mysql-proxy/logs/mysql-proxy.log log-level=info daemon=true keepalive=true ~
这里注意上述的配置在复制的时候注意每行后面一定不要有空格，否则会报如下的错误，尤其在复制他人博客的时候每行后面都有一个注释，就是这个地方会有空格出现。
Key file contains key 'daemon' which has value that cannot be interpreted.
启动mysql-proxy
/usr/local/mysql-proxy/bin/mysql-proxy --defaults-file=/etc/mysql-proxy.cnf --plugins=proxy --plugins=admin
启动后查看进程和端口：
5、创建用于读写分离的数据库连接用户
登陆主数据库服务器192.168.2.201，通过命令行登录管理MySQL服务器
[root@sqldb01 opt]# mysql -uroot -p1234 mysql> GRANT ALL ON *.* TO 'wyl'@'192.168.%.%' IDENTIFIED BY '1234'; mysql>flush privileges;
由于我们配置了主从复制功能，因此从数据库服务器192.168.2.202上已经同步了此操作。
6、在mysql-proxy的机器上进入后发现已经变成代理的mysql，version:5.0.99-agent-admin。
当输入如下指令进入数据库明令行时，可以对数据库增删改查操作。
mysql -uwyl -p1234 -h 192.168.2.203 -P4040
执行多次查询和插入询操作，如果出现下面图中的state都是up状态，则表示读写分离功能实现。