基于mysql主从同步的proxy读写分离
mysql-proxy 简介
MySQL Proxy是一个处于你的client端和MySQL server端之间的简单程序,它可以监测、分析或改变它们的通信。它使用灵活,没有限制,常见的用途包括:负载平衡,故障、查询分析,查询过滤和修改等等。
MySQL Proxy就是这么一个中间层代理,简单的说,MySQL Proxy就是一个连接池,负责将前台应用的连接请求转发给后台的数据库,并且通过使用lua脚本,可以实现复杂的连接控制和过滤,从而实现读写分离和负载平衡。对于应用来说,MySQL Proxy是完全透明的,应用则只需要连接到MySQL Proxy的监听端口即可。当然,这样proxy机器可能成为单点失效,但完全可以使用多个proxy机器做为冗余,在应用服务器的连接池配置中配置到多个proxy的连接参数即可。
MySQL Proxy更强大的一项功能是实现“读写分离”,基本原理是让主数据库处理事务性查询,让从库处理SELECT查询。数据库复制被用来把事务性查询导致的变更同步到集群中的从库。
架构示意图
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___ master_mysql(10.10.10.3) | | mysql-proxy(10.10.10.2) | |___ | slave_mysql(10.10.10.4) |
(一)mysql主从同步
1、mysql-master设置
(1)
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server- id = 1 //master 端ID号 binlog-ignore-db = // 设置不同步的sql库 binlog- do -db= // 设置同步的数据 |
(2)设置完上面以后重启mysql
(3)添加用户访问主库,并且只有备份权限
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mysql > grant replication slave on *.* to 'rsync' @ '10.10.%' identified by '1q2w3e4rys' with grant option; mysql > flush privileges; |
(4)锁表,主库数据继续写入
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mysql > flush tables with read lock; |
(5)记录 master file与position的值,slave库配置同步时候要使用
(6)导出mysql主库数据
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mysqldump -uuser -p databases > databases.sql |
注:这里有个问题,当主库数据上G,较大时需要做如下操作
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--max_allowed_packet=XXX // 客户端/服务器之间通信的缓存区的最大大小; --net_buffer_length=XXX //TCP/IP 和套接字通信缓冲区大小,创建长度达net_buffer_length的行; |
注意:max_allowed_packet和net_buffer_length不能比目标数据库的配置数值大,否则可能出错。
首先确定目标库的参数值
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mysql>show variables like 'max_allowed_packet' ; mysql>show variables like 'net_buffer_length' ; |
根据参数值书写mysqldump命令,如:
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mysql > mysqldump -uuser -p? 数据库名 -e --max_allowed_packet=1048576 --net_buffer_length=16384 > databases.sql |
(7)master库同步到slave服务器上
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# scp databases.sql root@host:/path |
2、mysql-slave设置
(1)
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server- id = 2 |
(2)登录mysql创建sql数据库
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mysql > CREATE DATABASE `?sql_db?` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci; |
(3)导入master库数据到slave库中
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mysql -uuser -p? sql_db < databases.sql |
(4)登录mysql停止slave
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mysql > stop slave; |
(5)配置从库同步
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mysql > change master to master_host=’10.10.10.2’,master_user=’ rsync ’,master_password=’1q2w3e4rys’,master_port=3306,master_log_file=’mysql-bin.000047’,master_log_pos=107; |
(6)启动同步功能
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mysql > start slave; |
(7)解除主库锁表
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unlock tables; |
(8)查看slave同步状态
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mysql > show slave status\G // 多执行几遍,查看数据写入后的状态 |
注:查看上面的Slave_IO_Running: Yes 和Slave_SQL_Running: Yes 2个都为yes则证明主从同步正常,如果有任一个显示NO,则证明同步有问题.可以查看数据库日志文件,里面基本上会显示出错误之处,根据错误一步一步排查,基本上都可以解决的.
(二)mysql-proxy读写分离
1、安装mysql-proxy
(1)
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# wget http://ftp.ntu.edu.tw/pub/MySQL/Downloads/MySQL-Proxy/mysql-proxy-0.8.5-linux-el6-x86-64bit.tar.gz # tar xf mysql-proxy-0.8.5-linux-el6-x86-64bit.tar.gz -C /usr/local # cd /usr/local # ln -sv mysql-proxy-0.8.5-linux-el6-x86-64bit mysql-proxy |
2、设置mysql-proxy属主属组
(1)
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# groupadd mysql-proxy # useradd -g mysql-proxy -s /sbin//nologin -M mysql-proxy |
3、配置mysql-proxy
(1)为mysql-proxy提供SysV服务脚本,脚本如下:
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#!/bin/bash # # mysql-proxy This script starts and stops the mysql-proxy daemon # # chkconfig: - 78 30 # processname: mysql-proxy # description: mysql-proxy is a proxy daemon for mysql # Source function library. . /etc/rc .d /init .d /functions prog= "/usr/local/mysql-proxy/bin/mysql-proxy" # Source networking configuration. if [ -f /etc/sysconfig/network ]; then . /etc/sysconfig/network fi # Check that networking is up. [ ${NETWORKING} = "no" ] && exit 0 # Set default mysql-proxy configuration. ADMIN_USER= "admin" ADMIN_PASSWD= "admin" ADMIN_LUA_SCRIPT= "/usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua" PROXY_OPTIONS= "--daemon" PROXY_PID= /var/run/mysql-proxy .pid PROXY_USER= "mysql-proxy" # Source mysql-proxy configuration. if [ -f /etc/sysconfig/mysql-proxy ]; then . /etc/sysconfig/mysql-proxy fi RETVAL=0 start() { echo -n $ "Starting $prog: " daemon $prog $PROXY_OPTIONS --pid- file =$PROXY_PID --proxy-address= "$PROXY_ADDRESS" --user=$PROXY_USER --admin-username= "$ADMIN_USER" --admin-lua-script= "$ADMIN_LUA_SCRIPT" --admin-password= "$ADMIN_PASSWORD" RETVAL=$? echo if [ $RETVAL - eq 0 ]; then touch /var/lock/subsys/mysql-proxy fi } stop() { echo -n $ "Stopping $prog: " killproc -p $PROXY_PID -d 3 $prog RETVAL=$? echo if [ $RETVAL - eq 0 ]; then rm -f /var/lock/subsys/mysql-proxy rm -f $PROXY_PID fi } # See how we were called. case "$1" in start) start ;; stop) stop ;; restart) stop start ;; condrestart|try-restart) if status -p $PROXY_PIDFILE $prog >& /dev/null ; then stop start fi ;; status) status -p $PROXY_PID $prog ;; *) echo "Usage: $0 {start|stop|restart|reload|status|condrestart|try-restart}" RETVAL=1 ;; esac exit $RETVAL |
(2)将上述内容保存为/etc/rc.d/init.d/mysql-proxy,给予执行权限,而后加入到服务列表。
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# chmod +x /etc/rc.d/init.d/mysql-proxy # chkconfig --add mysql-proxy |
(3)为服务脚本提供配置文件/etc/sysconfig/mysql-proxy,内容如下所示:
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# Options for mysql-proxy ADMIN_USER= "admin" ADMIN_PASSWORD= "admin" ADMIN_ADDRESS= "" ADMIN_LUA_SCRIPT= "/usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua" PROXY_ADDRESS= "" PROXY_USER= "mysql-proxy" PROXY_OPTIONS= "--daemon --log-level=info --log-use-syslog --plugins=proxy --plugins=admin --proxy-backend-addresses=10.10.10.3:3306 --proxy-read-only-backend-addresses=10.10.10.4:3306 --proxy-lua-script=/usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua" |
(4)mysql-proxy配置选项注解
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--help --help-admin --help-proxy --help-all ———— 以上四个选项均用于获取帮助信息; --proxy-address=host:port ———— 代理服务监听的地址和端口; --admin-address=host:port ———— 管理模块监听的地址和端口; --proxy-backend-addresses=host:port ———— 后端mysql服务器的地址和端口; --proxy- read -only-backend-addresses=host:port ———— 后端只读mysql服务器的地址和端口; --proxy-lua-script=file_name ———— 完成mysql代理功能的Lua脚本; --daemon ———— 以守护进程模式启动mysql-proxy; --keepalive ———— 在mysql-proxy崩溃时尝试重启之; --log- file = /path/to/log_file_name ———— 日志文件名称; --log-level=level ———— 日志级别; --log-use-syslog ———— 基于syslog记录日志; --plugins=plugin,.. ———— 在mysql-proxy启动时加载的插件; --user=user_name ———— 运行mysql-proxy进程的用户; --defaults- file = /path/to/conf_file_name ———— 默认使用的配置文件路径;其配置段使用[mysql-proxy]标识; --proxy-skip-profiling ———— 禁用profile; --pid- file = /path/to/pid_file_name ———— 进程文件名; |
(5)复制如下内容建立admin.lua文件,将其保存至/usr/local/mysql-proxy/share/doc/mysql-proxy/目录中.
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--[[ $%BEGINLICENSE%$ 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 |
(6)测试
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#mysql -uadmin -padmin -h110.10.10.2 --port=4041 mysql > SELECT * FROM backends; |
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+-------------+-------------------+-------+------+------+-------------------+ | backend_ndx | address | state | type | uuid | connected_clients | +-------------+-------------------+-------+------+------+-------------------+ | 1 | 10.10.10.3:3306 | up | rw | NULL | 0 | | 2 | 10.10.10.4:3306 | up | ro | NULL | 0 | +-------------+-------------------+-------+------+------+-------------------+ 2 rows in set (0.00 sec) |
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