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目录
[1.1 环境准备:](#1.1 环境准备:)
[1.2 创建相关目录初始化数据](#1.2 创建相关目录初始化数据)
[1.3 准备DB01配置文件和启动脚本](#1.3 准备DB01配置文件和启动脚本)
[1.4 准备DB02配置文件和启动脚本](#1.4 准备DB02配置文件和启动脚本)
[1.5 修改权限,启动多实例](#1.5 修改权限,启动多实例)
[1.6 节点主从规划](#1.6 节点主从规划)
[1.7 分片规划](#1.7 分片规划)
[1.8 开始配置](#1.8 开始配置)
[# 192.168.8.10:3307 <-----> 192.168.8.20:3307](# 192.168.8.10:3307 <-----> 192.168.8.20:3307)
[## db02:](## db02:)
[## db01:](## db01:)
[## db02:](## db02:)
[# 192.168.8.10:3309 ------> 192.168.8.10:3307](# 192.168.8.10:3309 ------> 192.168.8.10:3307)
[## db01:](## db01:)
[# 192.168.8.20:3309 ------> 192.168.8.20:3307](# 192.168.8.20:3309 ------> 192.168.8.20:3307)
[## db02:](## db02:)
[#192.168.8.20:3308 <-----> 192.168.8.10:3308](#192.168.8.20:3308 <-----> 192.168.8.10:3308)
[## db01:](## db01:)
[## db02:](## db02:)
[## db01:](## db01:)
[# 192.168.8.20:3310 -----> 192.168.8.20:3308](# 192.168.8.20:3310 -----> 192.168.8.20:3308)
[## db02:](## db02:)
[# 192.168.8.10:3310 -----> 192.168.8.10:3308](# 192.168.8.10:3310 -----> 192.168.8.10:3308)
[## db01:](## db01:)
[1.9 检测主从状态](#1.9 检测主从状态)
注:如果中间出现错误,在每个节点进行执行以下命令,从第1.8步重新开始即可
[mysql -S /data/3307/mysql.sock -e "stop slave; reset slave all;"mysql -S /data/3308/mysql.sock -e "stop slave; reset slave all;"mysql -S /data/3309/mysql.sock -e "stop slave; reset slave all;"mysql -S /data/3310/mysql.sock -e "stop slave; reset slave all;"](#mysql -S /data/3307/mysql.sock -e "stop slave; reset slave all;"mysql -S /data/3308/mysql.sock -e "stop slave; reset slave all;"mysql -S /data/3309/mysql.sock -e "stop slave; reset slave all;"mysql -S /data/3310/mysql.sock -e "stop slave; reset slave all;")
[1.3 解压文件](#1.3 解压文件)
[1.4 软件目录结构](#1.4 软件目录结构)
[1.5 启动和连接](#1.5 启动和连接)
[四. 数据库分布式架构方式](#四. 数据库分布式架构方式)
[1.1 垂直拆分](#1.1 垂直拆分)
[1.2 水平拆分](#1.2 水平拆分)
[2.2 主要配置文件介绍](#2.2 主要配置文件介绍)
[2.3 用户创建及数据库导入](#2.3 用户创建及数据库导入)
[2.4 配置文件结构介绍](#2.4 配置文件结构介绍)
[mycat 逻辑库定义:](#mycat 逻辑库定义:)
[3.1 mycat实现1主1从读写分离](#3.1 mycat实现1主1从读写分离)
[3.2 Mycat高可用+读写分离](#3.2 Mycat高可用+读写分离)
[3.3 配置中的属性介绍:](#3.3 配置中的属性介绍:)
[4. Mycat高级应用-分布式解决方案](#4. Mycat高级应用-分布式解决方案)
[4.1 垂直分表](#4.1 垂直分表)
[重启mycat :](#重启mycat :)
[4.2 Mycat分布式-水平拆分(分片)介绍](#4.2 Mycat分布式-水平拆分(分片)介绍)
[4.3 Mycat分布式-范围分片](#4.3 Mycat分布式-范围分片)
[4.4 取模分片(mod-long):](#4.4 取模分片(mod-long):)
[4.5 枚举分片](#4.5 枚举分片)
前言:
在当今数据驱动的时代,数据库的性能和可扩展性成为了企业IT架构中不可忽视的关键要素。随着数据量的爆炸式增长,传统的单节点MySQL数据库逐渐暴露出性能瓶颈和扩展性受限的问题。为了应对这些挑战,分布式数据库架构应运而生,而Mycat作为一款开源的数据库中间件,凭借其强大的数据分片、读写分离和动态扩展能力,在MySQL分布式部署领域崭露头角。
本文旨在深入探讨Mycat在MySQL分布式部署中的应用与实践。我们将从Mycat的基本概念入手,逐步揭开其神秘面纱,详细解析其工作原理、配置方法以及性能优化策略。通过丰富的实战案例和详细的操作步骤,帮助读者快速掌握Mycat的使用技巧,从而有效提升MySQL数据库的性能和可扩展性。
接下来就让我们一起来探讨mycat吧!

正文:
一.mycat基本介绍
Mycat是一个开源的分布式数据库系统,其核心功能是分表分库,即将一个大表水平分割为多个小表,
存储在后端MySQL或者其他数据库里。取名Mycat原因一是简单好记,另一个则是希望未来能够入驻 Apache,
Apache的开源产品Tomcat也是一只猫。
MyCAT 是一个彻底开源的,面向企业应用开发的"大数据库集群" 支持事务、ACID、可以替代Mysql的加强版数据库;
一个可以视为"Mysql"集群的企业级数据库,用来替代昂贵的Oracle集群 ; 一个融合内存缓存技术、Nosql技术、
HDFS大数据的新型SQL Server; 结合传统数据库和新型分布式数据仓库的新一代企业级数据库产品 ; 一个新颖的
数据库中间件产品。
二.MyCAT基础架构准备
1.1 环境准备:
两台虚拟机 db01 db02
每台创建四个mysql实例:3307 3308 3309 3310
1.2 创建相关目录初始化数据
mkdir /data/33{07..10}/data -p
mysqld --initialize-insecure --user=mysql --datadir=/data/3307/data --basedir=/usr/local/mysql
mysqld --initialize-insecure --user=mysql --datadir=/data/3308/data --basedir=/usr/local/mysql
mysqld --initialize-insecure --user=mysql --datadir=/data/3309/data --basedir=/usr/local/mysql
mysqld --initialize-insecure --user=mysql --datadir=/data/3310/data --basedir=/usr/local/mysql
1.3 准备DB01配置文件和启动脚本
cat >/data/3307/my.cnf<<EOF
[mysqld]
basedir=/usr/local/mysql
datadir=/data/3307/data
socket=/data/3307/mysql.sock
port=3307
log-error=/data/3307/mysql.log
log_bin=/data/3307/mysql-bin
binlog_format=row
skip-name-resolve
server-id=7
gtid-mode=on
enforce-gtid-consistency=true
log-slave-updates=1
EOF
cat >/data/3308/my.cnf<<EOF
[mysqld]
basedir=/usr/local/mysql
datadir=/data/3308/data
port=3308
socket=/data/3308/mysql.sock
log-error=/data/3308/mysql.log
log_bin=/data/3308/mysql-bin
binlog_format=row
skip-name-resolve
server-id=8
gtid-mode=on
enforce-gtid-consistency=true
log-slave-updates=1
EOF
cat >/data/3309/my.cnf<<EOF
[mysqld]
basedir=/usr/local/mysql
datadir=/data/3309/data
socket=/data/3309/mysql.sock
port=3309
log-error=/data/3309/mysql.log
log_bin=/data/3309/mysql-bin
binlog_format=row
skip-name-resolve
server-id=9
gtid-mode=on
enforce-gtid-consistency=true
log-slave-updates=1
EOF
cat >/data/3310/my.cnf<<EOF
[mysqld]
basedir=/usr/local/mysql
datadir=/data/3310/data
socket=/data/3310/mysql.sock
port=3310
log-error=/data/3310/mysql.log
log_bin=/data/3310/mysql-bin
binlog_format=row
skip-name-resolve
server-id=10
gtid-mode=on
enforce-gtid-consistency=true
log-slave-updates=1
EOF
cat >/etc/systemd/system/mysqld3307.service<<EOF
[Unit]
Description=MySQL Server
Documentation=man:mysqld(8)
Documentation=http://dev.mysql.com/doc/refman/en/using-systemd.html
After=network.target
After=syslog.target
[Install]
WantedBy=multi-user.target
[Service]
User=mysql
Group=mysql
ExecStart=/usr/local/mysql/bin/mysqld --defaults-file=/data/3307/my.cnf
LimitNOFILE = 5000
EOF
cat >/etc/systemd/system/mysqld3308.service<<EOF
[Unit]
Description=MySQL Server
Documentation=man:mysqld(8)
Documentation=http://dev.mysql.com/doc/refman/en/using-systemd.html
After=network.target
After=syslog.target
[Install]
WantedBy=multi-user.target
[Service]
User=mysql
Group=mysql
ExecStart=/usr/local/mysql/bin/mysqld --defaults-file=/data/3308/my.cnf
LimitNOFILE = 5000
EOF
cat >/etc/systemd/system/mysqld3309.service<<EOF
[Unit]
Description=MySQL Server
Documentation=man:mysqld(8)
Documentation=http://dev.mysql.com/doc/refman/en/using-systemd.html
After=network.target
After=syslog.target
[Install]
WantedBy=multi-user.target
[Service]
User=mysql
Group=mysql
ExecStart=/usr/local/mysql/bin/mysqld --defaults-file=/data/3309/my.cnf
LimitNOFILE = 5000
EOF
cat >/etc/systemd/system/mysqld3310.service<<EOF
[Unit]
Description=MySQL Server
Documentation=man:mysqld(8)
Documentation=http://dev.mysql.com/doc/refman/en/using-systemd.html
After=network.target
After=syslog.target
[Install]
WantedBy=multi-user.target
[Service]
User=mysql
Group=mysql
ExecStart=/usr/local/mysql/bin/mysqld --defaults-file=/data/3310/my.cnf
LimitNOFILE = 5000
EOF
1.4 准备DB02配置文件和启动脚本
cat >/data/3307/my.cnf<<EOF
[mysqld]
basedir=/usr/local/mysql
datadir=/data/3307/data
socket=/data/3307/mysql.sock
port=3307
log-error=/data/3307/mysql.log
log_bin=/data/3307/mysql-bin
binlog_format=row
skip-name-resolve
server-id=17
gtid-mode=on
enforce-gtid-consistency=true
log-slave-updates=1
EOF
cat >/data/3308/my.cnf<<EOF
[mysqld]
basedir=/usr/local/mysql
datadir=/data/3308/data
port=3308
socket=/data/3308/mysql.sock
log-error=/data/3308/mysql.log
log_bin=/data/3308/mysql-bin
binlog_format=row
skip-name-resolve
server-id=18
gtid-mode=on
enforce-gtid-consistency=true
log-slave-updates=1
EOF
cat >/data/3309/my.cnf<<EOF
[mysqld]
basedir=/usr/local/mysql
datadir=/data/3309/data
socket=/data/3309/mysql.sock
port=3309
log-error=/data/3309/mysql.log
log_bin=/data/3309/mysql-bin
binlog_format=row
skip-name-resolve
server-id=19
gtid-mode=on
enforce-gtid-consistency=true
log-slave-updates=1
EOF
cat >/data/3310/my.cnf<<EOF
[mysqld]
basedir=/usr/local/mysql
datadir=/data/3310/data
socket=/data/3310/mysql.sock
port=3310
log-error=/data/3310/mysql.log
log_bin=/data/3310/mysql-bin
binlog_format=row
skip-name-resolve
server-id=20
gtid-mode=on
enforce-gtid-consistency=true
log-slave-updates=1
EOF
cat >/etc/systemd/system/mysqld3307.service<<EOF
[Unit]
Description=MySQL Server
Documentation=man:mysqld(8)
Documentation=http://dev.mysql.com/doc/refman/en/using-systemd.html
After=network.target
After=syslog.target
[Install]
WantedBy=multi-user.target
[Service]
User=mysql
Group=mysql
ExecStart=/usr/local/mysql/bin/mysqld --defaults-file=/data/3307/my.cnf
LimitNOFILE = 5000
EOF
cat >/etc/systemd/system/mysqld3308.service<<EOF
[Unit]
Description=MySQL Server
Documentation=man:mysqld(8)
Documentation=http://dev.mysql.com/doc/refman/en/using-systemd.html
After=network.target
After=syslog.target
[Install]
WantedBy=multi-user.target
[Service]
User=mysql
Group=mysql
ExecStart=/usr/local/mysql/bin/mysqld --defaults-file=/data/3308/my.cnf
LimitNOFILE = 5000
EOF
cat >/etc/systemd/system/mysqld3309.service<<EOF
[Unit]
Description=MySQL Server
Documentation=man:mysqld(8)
Documentation=http://dev.mysql.com/doc/refman/en/using-systemd.html
After=network.target
After=syslog.target
[Install]
WantedBy=multi-user.target
[Service]
User=mysql
Group=mysql
ExecStart=/usr/local/mysql/bin/mysqld --defaults-file=/data/3309/my.cnf
LimitNOFILE = 5000
EOF
cat >/etc/systemd/system/mysqld3310.service<<EOF
[Unit]
Description=MySQL Server
Documentation=man:mysqld(8)
Documentation=http://dev.mysql.com/doc/refman/en/using-systemd.html
After=network.target
After=syslog.target
[Install]
WantedBy=multi-user.target
[Service]
User=mysql
Group=mysql
ExecStart=/usr/local/mysql/bin/mysqld --defaults-file=/data/3310/my.cnf
LimitNOFILE = 5000
EOF
1.5 修改权限,启动多实例
chown -R mysql.mysql /data/*
systemctl start mysqld3307
systemctl start mysqld3308
systemctl start mysqld3309
systemctl start mysqld3310
mysql -S /data/3307/mysql.sock -e "show variables like 'server_id'"
mysql -S /data/3308/mysql.sock -e "show variables like 'server_id'"
mysql -S /data/3309/mysql.sock -e "show variables like 'server_id'"
mysql -S /data/3310/mysql.sock -e "show variables like 'server_id'"
1.6 节点主从规划

1.7 分片规划

1.8 开始配置
#第一组四节点结构
# 192.168.8.10:3307 <-----> 192.168.8.20:3307
## db02:
mysql -S /data/3307/mysql.sock -e "grant replication slave on *.* to repl@'192.168.8.%' identified by '123';"
mysql -S /data/3307/mysql.sock -e "grant all on *.* to root@'192.168.8.%' identified by '123' with grant option;"
## db01:
mysql -S /data/3307/mysql.sock -e "CHANGE MASTER TO MASTER_HOST='192.168.8.20', MASTER_PORT=3307, MASTER_AUTO_POSITION=1, MASTER_USER='repl', MASTER_PASSWORD='123';"
mysql -S /data/3307/mysql.sock -e "start slave;"
mysql -S /data/3307/mysql.sock -e "show slave status\G"
## db02:
mysql -S /data/3307/mysql.sock -e "CHANGE MASTER TO MASTER_HOST='192.168.8.10', MASTER_PORT=3307, MASTER_AUTO_POSITION=1, MASTER_USER='repl', MASTER_PASSWORD='123';"
mysql -S /data/3307/mysql.sock -e "start slave;"
mysql -S /data/3307/mysql.sock -e "show slave status\G"
=======================
# 192.168.8.10:3309 ------> 192.168.8.10:3307
## db01:
mysql -S /data/3309/mysql.sock -e "CHANGE MASTER TO MASTER_HOST='192.168.8.10', MASTER_PORT=3307, MASTER_AUTO_POSITION=1, MASTER_USER='repl', MASTER_PASSWORD='123';"
mysql -S /data/3309/mysql.sock -e "start slave;"
mysql -S /data/3309/mysql.sock -e "show slave status\G"
# 192.168.8.20:3309 ------> 192.168.8.20:3307
## db02:
mysql -S /data/3309/mysql.sock -e "CHANGE MASTER TO MASTER_HOST='192.168.8.20', MASTER_PORT=3307, MASTER_AUTO_POSITION=1, MASTER_USER='repl', MASTER_PASSWORD='123';"
mysql -S /data/3309/mysql.sock -e "start slave;"
mysql -S /data/3309/mysql.sock -e "show slave status\G"
#第二组四节点
#192.168.8.20:3308 <-----> 192.168.8.10:3308
## db01:
mysql -S /data/3308/mysql.sock -e "grant replication slave on *.* to repl@'192.168.8%' identified by '123';"
mysql -S /data/3308/mysql.sock -e "grant all on *.* to root@'192.168.8.%' identified by '123' with grant option;"
## db02:
mysql -S /data/3308/mysql.sock -e "CHANGE MASTER TO MASTER_HOST='192.168.8.10', MASTER_PORT=3308, MASTER_AUTO_POSITION=1, MASTER_USER='repl', MASTER_PASSWORD='123';"
mysql -S /data/3308/mysql.sock -e "start slave;"
mysql -S /data/3308/mysql.sock -e "show slave status\G"
## db01:
mysql -S /data/3308/mysql.sock -e "CHANGE MASTER TO MASTER_HOST='192.168.8.20', MASTER_PORT=3308, MASTER_AUTO_POSITION=1, MASTER_USER='repl', MASTER_PASSWORD='123';"
mysql -S /data/3308/mysql.sock -e "start slave;"
mysql -S /data/3308/mysql.sock -e "show slave status\G"
# 192.168.8.20:3310 -----> 192.168.8.20:3308
## db02:
mysql -S /data/3310/mysql.sock -e "CHANGE MASTER TO MASTER_HOST='192.168.8.20', MASTER_PORT=3308, MASTER_AUTO_POSITION=1, MASTER_USER='repl', MASTER_PASSWORD='123';"
mysql -S /data/3310/mysql.sock -e "start slave;"
mysql -S /data/3310/mysql.sock -e "show slave status\G"
# 192.168.8.10:3310 -----> 192.168.8.10:3308
## db01:
mysql -S /data/3310/mysql.sock -e "CHANGE MASTER TO MASTER_HOST='192.168.8.10', MASTER_PORT=3308, MASTER_AUTO_POSITION=1, MASTER_USER='repl', MASTER_PASSWORD='123';"
mysql -S /data/3310/mysql.sock -e "start slave;"
mysql -S /data/3310/mysql.sock -e "show slave status\G"
1.9 检测主从状态
mysql -S /data/3307/mysql.sock -e "show slave status\G"|grep Yes
mysql -S /data/3308/mysql.sock -e "show slave status\G"|grep Yes
mysql -S /data/3309/mysql.sock -e "show slave status\G"|grep Yes
mysql -S /data/3310/mysql.sock -e "show slave status\G"|grep Yes
注:如果中间出现错误,在每个节点进行执行以下命令,从第1.8步重新开始即可
**mysql -S /data/3307/mysql.sock -e "stop slave; reset slave all;"
mysql -S /data/3308/mysql.sock -e "stop slave; reset slave all;"
mysql -S /data/3309/mysql.sock -e "stop slave; reset slave all;"
mysql -S /data/3310/mysql.sock -e "stop slave; reset slave all;"**
三.MyCAT安装
1.1 预先安装Java运行环境
yum install -y java
1.2下载
1.3 解压文件
tar xf Mycat-server-1.6.7.1-release-20190627191042-linux.tar.gz -C /usr/local
1.4 软件目录结构
ls /usr/local/mycat
1.5 启动和连接
配置环境变量
vim /etc/profile
末尾追加:
export PATH=/usr/local/mycat/bin:$PATH
保存退出
source /etc/profile
启动
vim /usr/local/mycat/conf/wrapper.conf
添加:
wrapper.startup.timeout=300
保存退出
mycat start
连接mycat:
mysql -uroot -p123456 -h 127.0.0.1 -P8066
四. 数据库分布式架构方式
1.1 垂直拆分
1.2 水平拆分
range
取模
枚举
hash
时间
等等
2.1Mycat基础应用
2.2 主要配置文件介绍

2.3 用户创建及数据库导入
db01:
mysql -S /data/3307/mysql.sock
grant all on *.* to root@'192.168.8.%' identified by '123';
source /root/world.sql
exit
mysql -S /data/3308/mysql.sock
grant all on *.* to root@'192.168.8.%' identified by '123';
source /root/world.sql
2.4 配置文件结构介绍
cd /usr/local/mycat/conf
mv schema.xml schema.xml.bak
vim schema.xml
<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://io.mycat/">
mycat 逻辑库定义:
<schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="100" dataNode="sh1">
</schema>
==================================================
数据节点定义:
<dataNode name="sh1" dataHost="laoli1" database= "world" />
==================================================
后端主机定义:
<dataHost name="laoli1" maxCon="1000" minCon="10" balance="1" writeType="0" dbType="mysql" dbDriver="native" switchType="1">
<heartbeat>select user()</heartbeat>
<writeHost host="db1" url="192.168.8.10:3307" user="root" password="123">
<readHost host="db2" url="192.168.8.10:3309" user="root" password="123" />
</writeHost>
</dataHost>
===================================================
文件结尾:
</mycat:schema>
3.1 mycat实现1主1从读写分离
vim schema.xml
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://io.mycat/">
<schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="100" dataNode="sh1">
</schema>
<dataNode name="sh1" dataHost="laoli1" database= "world" />
<dataHost name="laoli1" maxCon="1000" minCon="10" balance="1" writeType="0" dbType="mysql" dbDriver="native" switchType="1">
<heartbeat>select user()</heartbeat>
<writeHost host="db1" url="192.168.8.10:3307" user="root" password="123">
<readHost host="db2" url="192.168.8.10:3309" user="root" password="123" />
</writeHost>
</dataHost>
</mycat:schema>
重启mycat:
mycat restart
mysql -uroot -p123456 -h127.0.0.1 -P8066
use TESTDB
select @@server_id;
begin;select @@server_id;commit;
3.2 Mycat高可用+读写分离
mv schema.xml schema.xml.1
vim schema.xml
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://io.mycat/">
<schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="100" dataNode="sh1">
</schema>
<dataNode name="sh1" dataHost="laoli1" database= "world" />
<dataHost name="laoli1" maxCon="1000" minCon="10" balance="1" writeType="0" dbType="mysql" dbDriver="native" switchType="1">
<heartbeat>select user()</heartbeat>
<writeHost host="db1" url="192.168.8.10:3307" user="root" password="123">
<readHost host="db2" url="192.168.8.10:3309" user="root" password="123" />
</writeHost>
<writeHost host="db3" url="192.168.8.20:3307" user="root" password="123">
<readHost host="db4" url="192.168.8.20:3309" user="root" password="123" />
</writeHost>
</dataHost>
</mycat:schema>
说明:
<writeHost host="db1" url="192.168.8.10:3307" user="root" password="123">
<readHost host="db2" url="192.168.8.10:3309" user="root" password="123" />
</writeHost>
<writeHost host="db3" url="192.168.8.20:3307" user="root" password="123">
<readHost host="db4" url="192.168.8.20:3309" user="root" password="123" />
</writeHost>
第一个 whost: 192.168.8.10:3307 真正的写节点,负责写操作
第二个 whost: 192.168.8.20:3307 准备写节点,负责读,当 192.168.8.10:3307宕掉,会切换为真正的写节点
测试:
root@db01 conf\]#
mysql -uroot -p123456 -h 192.168.8.9 -P 8066
###### 读:
select @@server_id;
###### 写:
mysql> begin ;select @@server_id; commit;
#### 3.3 配置中的属性介绍:
##### balance属性
###### 负载均衡类型,目前的取值有3种:
1. balance="0", 不开启读写分离机制,所有读操作都发送到当前可用的writeHost上。
2. balance="1",全部的readHost与standby writeHost参与select语句的负载均衡,简单的说,
当双主双从模式(M1-\>S1,M2-\>S2,并且M1与 M2互为主备),正常情况下,M2,S1,S2都参与select语句的负载均衡。
3. balance="2",所有读操作都随机的在writeHost、readhost上分发。
##### writeType属性
###### 负载均衡类型,目前的取值有2种:
1. writeType="0", 所有写操作发送到配置的第一个writeHost,
第一个挂了切到还生存的第二个writeHost,重新启动后已切换后的为主,切换记录在配置文件中:dnindex.properties .
2. writeType="1",所有写操作都随机的发送到配置的writeHost,但不推荐使用
##### switchType属性
-1 表示不自动切换
1 默认值,自动切换
2 基于MySQL主从同步的状态决定是否切换 ,心跳语句为 show slave status
datahost其他配置
\
vim rule.xml
\
vim rule.xml
\