在高并发系统设计中，后端数据库的性能往往会成为系统的瓶颈，这时候就需要进行合理的设计，以分摊后端数据库的压力，比如在数据层前面构建缓存层、数据文件存放在RAID这样的设备、对数据进行分库分表分区存放、合理利用索引、进行数据的读写分离等。mysql-proxy提供了mysql数据库的读写分离能力，mysql-proxy通过Lua脚本能分析得出用户的sql请求，如果发现在是read请求，则会转化到master-slave模型的slave中，如果是write请求，则会转发到master中，以达到读写分离的目的，在一定程度上能大大增加系统的性能。下面来一步步通过mysql-proxy搭建mysql的读写分离。
一、环境准备
os：centos6.4
mysql-slave：version：5.6.13 ip：192.168.1.111
mysql-master：version：5.6.13 ip：192.168.1.110
mysql-proxy：version：0.85 ip：192.168.1.112
二、环境搭建
1、mysql主从复制搭建
mysql安装具体参考：http://crazytechnology.blog.51cto.com/6906973/1640197
tips：mysql从5.6起，主从复制中采用了GTID，GTID为每个数据库事务编码一个number，并为
每个server赋予一个global uuid，通过uuid和事务编号来进行数据的复制和恢复，这种方案更有利
于在高可用的环境中数据的恢复。在5.6后，mysql主从架构中还支持多线程复制，即可以启动多个
sql thread对relay log进行处理，默认的线程数建议为要同步的数据库的个数。
由于是搭建5.6.13的mysql主从架构，因上安装好mysql后。在/etc/my.cnf中主要配置如下：
master:
[mysqld]
port = 3306
datadir = /data/mysql
server_id = 1
socket = /tmp/mysql.sock
innodb_file_per_table = 1
log-bin = master-bin
binlog-format=ROW
log-slave-updates=true
gtid-mode=on
enforce-gtid-consistency=true
master-info-repository=TABLE
relay-log-info-repository=TABLE
sync-master-info=1
slave-parallel-workers=2
binlog-checksum=CRC32
master-verify-checksum=1
slave-sql-verify-checksum=1
binlog-rows-query-log_events=1
report-port=3306
report-host=master.lee.com
vim /etc/hosts添加一条条目
192.168.1.110 master.lee.com master
slave：
[mysqld]
datadir = /data/mysql #存放数据目录
port = 3306 #启动端口
server_id = 100 #server_id
socket = /tmp/mysql.sock
innodb_file_per_table = 1 #每表一个表空间
binlog-format=ROW
log-slave-updates=true
gtid-mode=on #启动gtid
enforce-gtid-consistency=true
master-info-repository=TABLE #master记录bin-log的位置（myql.slave_master_info）
relay-log-info-repository=TABLE #slave记录relay-log的地方，默认为file
sync-master-info=1 #启用后可确保无信息丢失
slave-parallel-workers=2 #启动的sql thread线程数
binlog-checksum=CRC32 #二进制校验算法crc32
master-verify-checksum=1 #启用复制有关的校验功能
slave-sql-verify-checksum=1 #启用复制有关的校验功能
binlog-rows-query-log_events=1 #记录相关事件信息，降低排错复杂度
report-port=3306 #通知给master的端口号
log-bin=mysql-bin.log #开启二进制日志功能，可以拥有自己的从服务器
report-host=slave.lee.com #通知给master的主机名
在master中创建主从复制用户
mysql> grant replication slave on *.* to ‘repluser‘@‘192.168.1.%‘ identified by ‘replpass‘;
在slave中连接master:
mysql> change master to master_host=‘192.168.1.110‘,master_user=‘repluser‘,master_password
=‘replpass‘,master_auto_position=1;
启动myql slave
mysql> start slave
2、安装mysql-proxy
tar xf mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit.tar.gz -C /usr/local
cd /usr/local
ln -sv mysql-proxy-0.8.5-linux-glibc2.3-x86-64bit/ mysql-proxy
创建mysql-proxy用户
useradd -r -s /sbin/nologin mysql-proxy
为mysql-proxy提供SysV脚本，将下面代码复制到/etc/init.d/mysql-proxy
#!/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
chmod +x /etc/init.d/mysql-proxy
chkconfig --add mysql-proxy
chkconfig mysql-proxy on
为mysql-prox提供服务脚本
vim /etc/sysconfig/mysql-proxy
DMIN_USER="admin" #管理员用户名
ADMIN_PASSWORD="admin" #管理员用户密码
ADMIN_ADDRESS="192.168.1.112:4041" #管理mysql-proxy监听的套接字
#admin lua脚本
ADMIN_LUA_SCRIPT="/usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua"
PROXY_ADDRESS="192.168.1.112:3306" #mysql-proxy监听的套接字
PROXY_USER="mysql-proxy" #启动mysql-proxy服务的用户
#mysql-proxy启动的选项
PROXY_OPTIONS="--daemon --log-level=debug --log-use-syslog --plugins=proxy --plugins=admin --proxy-backend-addresses=192.168.1.110:3306 --proxy-read-only-backend-addresses=192.168.1.111:3306 --proxy-lua-script=/usr/local/mysql-proxy/share/doc/mysql-proxy/rw-splitting.lua
#--daemon：以守护进程方式启动
#--log-level=debug，日志级别,此处为了调试而用
#--log-use-syslog ： 通过系统的syslog记录日志
#--plugins：插件
#--proxy-backend-addresses：后台读写数据库服务器(rw)，可添加多个
#--proxy-read-only-backend-addresses：后台只读数据库服务器(ro)，可添加多个
#--proxy-lua-script：mysql读写分离lua脚本
复制下面代码，到/usr/local/mysql-proxy/share/doc/mysql-proxy/admin.lua文件中
--[[ $%BEGINLICENSE%$
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
启动mysql-proxy
service mysql-proxy start
查看是否启动成功
netstat -tlnp可查看到mysql-proxy监听在3306和4041（管理）端口上。
3、读写分离测试
在master中创建一个测试管理用户mproxyadmin
mysql> grant all on *.* to ‘mproxyadmin‘@‘192.168.1.112‘ identified by ‘mproxypass‘;
mysql> flush priviledges;
选择从slave中登录mysql-proxy
mysql -umproxyadmin -h192.168.1.112 -p;
登录进去
创建一个aa数据库
mysql> create database aa;
可以看到主从数据库都有已经创建了aa数据库。
在slave中登录mysql-proxy所的admin管理后台
mysql -uadmin -padmin -h192.168.1.112 --port=4041
管理后台只有一条sql语句有用，查看backends的状态信息：
mysql> select * from backends;
可看到此时的backends有两个，但状态为unknown.，且master为读写模式，slave为主从模式
当在主中进行相关非查询操作时，master的state会变成up。当进行查询时，slave的状态也会变
成up,当二者都激活后，mysql-proxy就能进行读写分离了。
由于mysql-proxy启动时日志级别设计为debug,所以在mysql-proxy所在机子可以轻易地看到日志
信息，首先在slave上连接上mysq_proxy，在刚才创建的aa数据库中创建一张test表，
这时在mysql-proxy中看到的日志是：
由is_slave为false可知道，这个创表语句是在master中执行的。
下面我们为这个表插入一条数据，然后再select出来
mysql> insert into test values(1,"test");
mysql> select * from test;
这时发现select语句，is_slave为true,也就是查询是在slave中执行的。
以后每执行查询操作都会在slave中执行，其它的操作都会在master中执行，这就实现了mysql的读写
分离。
本文出自 “向天飞” 博客，请务必保留此出处http://crazytechnology.blog.51cto.com/6906973/1641476
原文地址：http://crazytechnology.blog.51cto.com/6906973/1641476
