MMM高可用方案简介
MMM（Master-Master Replication Manager for MySQL）主主复制管理器，是一套提供了MySQL主主复制配置的监控、故障迁移和管理的可伸缩的脚本程序。在MMM高可用解决方案中，可以配置双主多从架构，通过MySQL Replication技术可以实现两台MySQL服务器互为主从，并且在任何时候只有一个节点可以写入，避免多节点写入的数据冲突，同时，当可写节点故障时，MMM套件可以立即监控到，然后将服务自动切换到另一个主节点继续提供服务，从而实现MySQL的高可用。
简而言之，通过MMM可以实现监控和管理MySQL主主复制和服务状态，同时也可以监控多个Slave节点的复制和运行状态，并且可以做到任意节点发生故障时实现自动切换的功能。MMM也为MySQL提供了读、写分离架构的良好平台。
MMM套件的优缺点
MMM集群套件具有良好的稳定性、高可用性和可扩展性。当活动的Master节点出现故障时，备用Master节点可以立即接管，而其他的Slave节点也能自动切换到备用Master节点继续进行同步复制，而无需人为干涉；MMM架构需要多个节点、多个IP，对服务器数量有要求，在读写非常繁忙的业务系统下表现不是很稳定，可能会出现复制延时、切换失效等问题。MMM方案并不太适应于对数据安全性要求很高，并且读、写繁忙的环境中。
MMM高可用套件工作原理
MMM套件主要的功能是通过以下三个脚本实现的：
1、mmm_mond：监控进程，运行在管理节点上，主要复制对所有数据库的监控工作，同时决定和处理所有节点的角色切换。
2、mmm_agentd：代理进程，运行在每一台MySQL服务器上，主要完成监控的测试工作和执行简单的远端服务设置。
3、mmm_control：一个简单的管理脚本，用来查看和管理集群运行状态，同时管理mmm_mond进程。
MMM高可用MySQL配置方案
在通过MMM套件实现的双Master架构中，需要5个IP地址，两个Master节点各有一个固定的物理IP，另外两个只读IP（reader IP）和一个可以IP（writer IP），这三个虚拟IP不会固定在任何一个节点上，相反，它会在两个Master节点之间来回切换（如何切换取决于节点的高可用）。在正常情况下Master1有两个虚拟IP（reader IP和writer IP），Master2有一个虚拟IP（reader IP），如果Master1故障，那么所有的reader和writer虚拟IP都会分配到Master上。
环境说明：
192.168.1.210
主Master可读、写
mysql-5.6.28 CentOS6.7
192.168.1.211
备Master可读、写
mysql-5.6.28 CentOS6.7
192.168.1.250
Slave节点只读
mysql-5.6.28 CentOS6.7
192.168.1.209
Slave节点只读 mysql-5.6.28 CentOS6.7
192.168.1.21
MMM服务管理端
mysql-5.6.28 CentOS6.7
虚拟IP地址：
192.168.1.230 写入VIP，仅支持单节点写入
MMM的安装和配置
Step1：MMM套件的安装
1、在MMM管理端monitor安装MMM所有套件
[root@monitor ~]# rpm -ivh epel-release-6-8.noarch.rpm [root@monitor ~]# yum install mysql-mmm mysql-mmm-agent mysql-mmm-tools mysql-mmm-monitor
2、在各个MySQL节点上安装mysql-mmm-agent服务
[root@master1 ~]# yum install mysql-mmm-agent [root@master2 ~]# yum install mysql-mmm-agent [root@slave1 ~]# yum install mysql-mmm-agent [root@slave2 ~]# yum install mysql-mmm-agent
Step2：Master1和两个Slave上配置主从（这里需要提前做好配置，Master1和Master2主主配置也一样）
1、Master1上授权slave1、2的复制用户
[root@master1 ~]# mysql -uroot -ppasswd mysql> grant replication slave on *.* to 'repl'@'192.168.1.250' identified by 'replpasswd'; mysql> grant replication slave on *.* to 'repl'@'192.168.1.209' identified by 'replpasswd'; mysql> flush privileges;
2、Slave1、2上设置指定Master1同步复制
[root@slave1 ~]# mysql -uroot -ppasswd mysql> change master to -> master_host='192.168.1.210', -> master_user='repl', -> master_password='replpasswd', -> master_port=3306, -> master_log_file='mysql-bin.000034', -> master_log_pos=120; Query OK, 0 rows affected, 2 warnings (0.06 sec)
[root@slave2 ~]# mysql -uroot -ppasswd mysql> change master to -> master_host='192.168.1.210', -> master_user='repl', -> master_password='replpasswd', -> master_port=3306, -> master_log_file='mysql-bin.000034', -> master_log_pos=120; Query OK, 0 rows affected, 2 warnings (0.02 sec)
Step3：在所有的MySQL节点的/etc/my.cnf中增加参数
read_only=1
Step4：在所有的MySQL节点添加以下两个用户
mysql> grant replication client on *.* to 'mmm_monitor'@'192.168.1.%' identified by 'monitorpasswd';
mysql> grant super, replication client, process on *.* to 'mmm_agent'@'192.168.1.%' identified by 'agentpasswd';
Step5：在MMM管理端monitor上配置mmm_common.conf
[root@monitor ~]# ls /etc/mysql-mmm/mmm_agent.conf mmm_common.conf #在所有的节点配置，配置相同 mmm_mon.conf #仅在MMM管理端配置 mmm_mon_log.conf mmm_tools.conf
vim /etc/mysql-mmm/mmm_common.conf 所有的MMM节点配置相同
active_master_role writer <host default> cluster_interface eth0 pid_path /var/run/mysql-mmm/mmm_agentd.pid bin_path /usr/libexec/mysql-mmm/ replication_user replication replication_password replication agent_user mmm_agent agent_password agentpasswd </host> <host db1> ip 192.168.1.210 mode master peer db2 </host> <host db2> ip 192.168.1.211 mode master peer db1 </host> <host db3> ip 192.168.1.209 mode slave </host> <host db4> ip 192.168.1.250 mode slave </host> <role writer> hosts db1, db2 ips 192.168.1.230 mode exclusive </role> <role reader> hosts db1, db2, db3, db4 ips 192.168.1.231, 192.168.1.232, 192.168.1.233, 192.168.1.234 mode balanced </role>
Step6：在MMM管理节点上配置mmm_mon.conf
[root@monitor ~]# vim /etc/mysql-mmm/mmm_mon.conf
include mmm_common.conf <monitor> ip 127.0.0.1 pid_path /var/run/mysql-mmm/mmm_mond.pid bin_path /usr/libexec/mysql-mmm status_path /var/lib/mysql-mmm/mmm_mond.status ping_ips 192.168.1.1, 192.168.1.2, 192.168.1.210, 192.168.1.211, 192.168.1.209, 192.168.1. 250 flap_duration 3600 flap_count 3 auto_set_online 8 # The kill_host_bin does not exist by default, though the monitor will # throw a warning about it missing. See the section 5.10 "Kill Host # Functionality" in the PDF documentation. # # kill_host_bin /usr/libexec/mysql-mmm/monitor/kill_host # </monitor> <host default> monitor_user mmm_monitor monitor_password monitorpasswd </host> debug 0
Step7：在所有的MySQL节点配置mmm_agent.conf
[root@master1 mysql]# vim /etc/mysql-mmm/mmm_agent.conf include mmm_common.conf this db1 #在四台mysql节点上设置对应的db，分别为db1、db2、db3、db4
Step8：所有节点设置ENABLED=1
cat /etc/default/mysql-mmm-agent # mysql-mmm-agent defaults ENABLED=1
Step9：启动MMM服务
在MMM管理端启动服务
[root@monitor ~]# /etc/init.d/mysql-mmm-monitor start
Starting MMM Monitor Daemon: [ OK ]
在每个mysql节点启动服务
[root@master1 ~]# /etc/init.d/mysql-mmm-agent start
Starting MMM Agent Daemon: [ OK ]
查看集群运行状态
[root@monitor mysql-mmm]# mmm_control show db1(192.168.1.210) master/AWAITING_RECOVERY. Roles: db2(192.168.1.211) master/AWAITING_RECOVERY. Roles: db3(192.168.1.209) slave/AWAITING_RECOVERY. Roles: db4(192.168.1.250) slave/AWAITING_RECOVERY. Roles:
若一直出现上面AWAITING_RECOVERY的状态，可以手动设置各个MySQL节点为online状态
[root@monitor ~]# mmm_control set_online db1 OK: State of 'db1' changed to ONLINE. Now you can wait some time and check its new roles! [root@monitor ~]# mmm_control set_online db2 OK: State of 'db2' changed to ONLINE. Now you can wait some time and check its new roles! [root@monitor ~]# mmm_control set_online db3 OK: State of 'db3' changed to ONLINE. Now you can wait some time and check its new roles! [root@monitor ~]# mmm_control set_online db4 OK: State of 'db4' changed to ONLINE. Now you can wait some time and check its new roles! [root@monitor ~]# mmm_control show db1(192.168.1.210) master/ONLINE. Roles: reader(192.168.1.234), writer(192.168.1.230) db2(192.168.1.211) master/ONLINE. Roles: reader(192.168.1.231) db3(192.168.1.209) slave/ONLINE. Roles: reader(192.168.1.232) db4(192.168.1.250) slave/ONLINE. Roles: reader(192.168.1.233)
检测各个节点的运行状态
[root@monitor ~]# mmm_control checks all db4 ping [last change: 2016/02/27 05:13:57] OK db4 mysql [last change: 2016/02/27 05:13:57] OK db4 rep_threads [last change: 2016/02/27 05:13:57] OK db4 rep_backlog [last change: 2016/02/27 05:13:57] OK: Backlog is null db2 ping [last change: 2016/02/27 05:13:57] OK db2 mysql [last change: 2016/02/27 05:13:57] OK db2 rep_threads [last change: 2016/02/27 05:13:57] OK db2 rep_backlog [last change: 2016/02/27 05:13:57] OK: Backlog is null db3 ping [last change: 2016/02/27 05:13:57] OK db3 mysql [last change: 2016/02/27 05:13:57] OK db3 rep_threads [last change: 2016/02/27 05:13:57] OK db3 rep_backlog [last change: 2016/02/27 05:13:57] OK: Backlog is null db1 ping [last change: 2016/02/27 05:13:57] OK db1 mysql [last change: 2016/02/27 05:13:57] OK db1 rep_threads [last change: 2016/02/27 05:13:57] OK db1 rep_backlog [last change: 2016/02/27 05:13:57] OK: Backlog is null
Step10：查看各节点虚拟IP分配情况
Master1
[root@master1 ~]# ip a |grep eth0 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 inet 192.168.1.210/24 brd 192.168.1.255 scope global eth0 inet 192.168.1.234/32 scope global eth0 inet 192.168.1.230/32 scope global eth0
Mster2
[root@master2 ~]# ip a |grep eth0 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 inet 192.168.1.211/24 brd 192.168.1.255 scope global eth0 inet 192.168.1.231/32 scope global eth0
Slave1
[root@slave1 ~]# ip a |grep eth0 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 inet 192.168.1.250/24 brd 192.168.1.255 scope global eth0 inet 192.168.1.213/32 scope global eth0 inet 192.168.1.233/32 scope global eth0
Slave2
[root@slave2 ~]# ip a |grep eth0 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 inet 192.168.1.209/24 brd 192.168.1.255 scope global eth0 inet 192.168.1.232/32 scope global eth0
Step11：测试MMM实现MySQL高可用
1、授权一个可以通过远程使用VIP登陆集群的用户
mysql> grant all on *.* to 'hm'@'192.168.1.%' identified by '741616710';
2、使用VIP192.168.1.230登陆，并做相关测试，在各个节点查看是否同步数据库
[root@monitor ~]# mysql -uhm -p741616710 -h192.168.1.230
mysql> show variables like 'hostname%'; +---------------+---------+ | Variable_name | Value | +---------------+---------+ | hostname | master1 | +---------------+---------+ 1 row in set (0.01 sec) mysql> create database test1; Query OK, 1 row affected (0.00 sec) mysql> use test1 Database changed mysql> create table tt1(id int, name varchar(20)); Query OK, 0 rows affected (0.13 sec) mysql> insert into tt1(id,name) values(1,'july'),(2,'dime'); Query OK, 2 rows affected (0.04 sec) Records: 2 Duplicates: 0 Warnings: 0 mysql> select * from tt1; +------+------+ | id | name | +------+------+ | 1 | july | | 2 | dime | +------+------+ 2 rows in set (0.00 sec)
Step12：测试MMM故障转移功能
1、关闭Master1上的MySQL服务，查看状态
[root@monitor ~]# mmm_control show db1(192.168.1.210) master/HARD_OFFLINE. Roles: db2(192.168.1.211) master/ONLINE. Roles: reader(192.168.1.231), writer(192.168.1.230) db3(192.168.1.209) slave/ONLINE. Roles: reader(192.168.1.232), reader(192.168.1.234) db4(192.168.1.250) slave/ONLINE. Roles: reader(192.168.1.233)
[root@monitor ~]# mmm_control set_online db1 OK: State of 'db1' changed to ONLINE. Now you can wait some time and check its new roles! [root@monitor ~]# mmm_control show db1(192.168.1.210) master/ONLINE. Roles: reader(192.168.1.232) db2(192.168.1.211) master/ONLINE. Roles: reader(192.168.1.231), writer(192.168.1.230) db3(192.168.1.209) slave/ONLINE. Roles: reader(192.168.1.234) db4(192.168.1.250) slave/ONLINE. Roles: reader(192.168.1.233)
2、Master1故障恢复后，若想让VIP继续回到Master1上，则可以按以下手动设置
[root@monitor ~]# mmm_control move_role writer db1 OK: Role 'writer' has been moved from 'db2' to 'db1'. Now you can wait some time and check new roles info!
[root@monitor ~]# mmm_control show db1(192.168.1.210) master/ONLINE. Roles: reader(192.168.1.232), writer(192.168.1.230) db2(192.168.1.211) master/ONLINE. Roles: reader(192.168.1.231) db3(192.168.1.209) slave/ONLINE. Roles: reader(192.168.1.234) db4(192.168.1.250) slave/ONLINE. Roles: reader(192.168.1.233)
MMM高可用MySQL结合Amoeba实现读写分离
Step1：Amoeba的安装
需准备除MMM集群之外的第六台服务器作为Amoeba服务器
1、Amoeba是基于Java开发的，因此需要安装Java环境
[root@amoeba ~]# java -version java version "1.8.0_65" Java(TM) SE Runtime Environment (build 1.8.0_65-b17) Java HotSpot(TM) 64-Bit Server VM (build 25.65-b01, mixed mode)
2、下载amoeba-mysql-3.0.5-RC-distribution.zip
http://nchc.dl.sourceforge.net/project/amoeba/Amoeba%20for%20mysql/3.x/amoeba-mysql-3.0.5-RC-distribution.zip
3、解压到/usr/local/目录下
[root@amoeba src]# unzip amoeba-mysql-3.0.5-RC-distribution.zip [root@amoeba src]# mv amoeba-mysql-3.0.5-RC /usr/local/amoeba [root@amoeba ~]# ls /usr/local/amoeba/ benchmark bin conf jvm.properties lib
Step2：配置Amoeba
[root@amoeba ~]# vim /usr/local/amoeba/conf/dbServers.xml
<?xml version="1.0" encoding="gbk"?>
<!DOCTYPE amoeba:dbServers SYSTEM "dbserver.dtd">
<amoeba:dbServers xmlns:amoeba="http://amoeba.meidusa.com/">
<!--
Each dbServer needs to be configured into a Pool,
If you need to configure multiple dbServer with load balancing that can be simplified
by the following configuration:
add attribute with name virtual = "true" in dbServer, but the configuration does not
allow the element with name factoryConfig
such as 'multiPool' dbServer
-->
<dbServer name="abstractServer" abstractive="true">
<factoryConfig class="com.meidusa.amoeba.mysql.net.MysqlServerConnectionFactory">
<property name="connectionManager">${defaultManager}</property>
<property name="sendBufferSize">64</property>
<property name="receiveBufferSize">128</property>
<!-- mysql port -->
<property name="port">3306</property>
<!-- mysql schema -->
<property name="schema">test1</property>
<!-- mysql user -->
<property name="user">hm</property>
<property name="password">741616710</property>
</factoryConfig>
<poolConfig class="com.meidusa.toolkit.common.poolable.PoolableObjectPool">
<property name="maxActive">500</property>
<property name="maxIdle">500</property>
<property name="minIdle">1</property>
<property name="minEvictableIdleTimeMillis">600000</property>
<property name="timeBetweenEvictionRunsMillis">600000</property>
<property name="testOnBorrow">true</property>
<property name="testOnReturn">true</property>
<property name="testWhileIdle">true</property>
</poolConfig>
</dbServer>
<dbServer name="writedb" parent="abstractServer">
<factoryConfig>
<!-- mysql ip -->
<property name="ipAddress">192.168.1.230</property>
</factoryConfig>
</dbServer>
<dbServer name="slave1" parent="abstractServer">
<factoryConfig>
<!-- mysql ip -->
<property name="ipAddress">192.168.1.231</property>
</factoryConfig>
</dbServer>
<dbServer name="slave2" parent="abstractServer">
<factoryConfig>
<!-- mysql ip -->
<property name="ipAddress">192.168.1.232</property>
</factoryConfig>
</dbServer>
<dbServer name="slave3" parent="abstractServer">
<factoryConfig>
<!-- mysql ip -->
<property name="ipAddress">192.168.1.233</property>
</factoryConfig>
</dbServer>
<dbServer name="slave4" parent="abstractServer">
<factoryConfig>
<!-- mysql ip -->
<property name="ipAddress">192.168.1.234</property>
</factoryConfig>
</dbServer>
<dbServer name="myslaves" virtual="true">
<poolConfig class="com.meidusa.amoeba.server.MultipleServerPool">
<!-- Load balancing strategy: 1=ROUNDROBIN , 2=WEIGHTBASED , 3=HA-->
<property name="loadbalance">1</property>
<!-- Separated by commas,such as: server1,server2,server1 -->
<property name="poolNames">slave1,slave2,slave3,slave4</property>
</poolConfig>
</dbServer>
</amoeba:dbServers>
[root@amoeba ~]# vim /usr/local/amoeba/conf/amoeba.xml
<?xml version="1.0" encoding="gbk"?>
<!DOCTYPE amoeba:configuration SYSTEM "amoeba.dtd">
<amoeba:configuration xmlns:amoeba="http://amoeba.meidusa.com/">
<proxy>
<!-- service class must implements com.meidusa.amoeba.service.Service -->
<service name="Amoeba for Mysql" class="com.meidusa.amoeba.mysql.server.MySQLService">
<!-- port -->
<property name="port">8066</property>
<!-- bind ipAddress -->
<!--
<property name="ipAddress">127.0.0.1</property>
-->
<property name="connectionFactory">
<bean class="com.meidusa.amoeba.mysql.net.MysqlClientConnectionFactory">
<property name="sendBufferSize">128</property>
<property name="receiveBufferSize">64</property>
</bean>
</property>
<property name="authenticateProvider">
<bean class="com.meidusa.amoeba.mysql.server.MysqlClientAuthenticator">
<property name="user">root</property>
<property name="password">741616710</property>
<property name="filter">
<bean class="com.meidusa.toolkit.net.authenticate.server.IPAcc
essController">
<property name="ipFile">${amoeba.home}/conf/access_lis
t.conf</property>
</bean>
</property>
</bean>
</property>
</service>
<runtime class="com.meidusa.amoeba.mysql.context.MysqlRuntimeContext">
<!-- proxy server client process thread size -->
<property name="executeThreadSize">128</property>
<!-- per connection cache prepared statement size -->
<property name="statementCacheSize">500</property>
<!-- default charset -->
<property name="serverCharset">utf8</property>
<!-- query timeout( default: 60 second , TimeUnit:second) -->
<property name="queryTimeout">60</property>
</runtime>
</proxy>
<!--
Each ConnectionManager will start as thread
manager responsible for the Connection IO read , Death Detection
-->
<connectionManagerList>
<connectionManager name="defaultManager" class="com.meidusa.toolkit.net.MultiConnectionManager
Wrapper">
<property name="subManagerClassName">com.meidusa.toolkit.net.AuthingableConnectionMana
ger</property>
</connectionManager>
</connectionManagerList>
<!-- default using file loader -->
<dbServerLoader class="com.meidusa.amoeba.context.DBServerConfigFileLoader">
<property name="configFile">${amoeba.home}/conf/dbServers.xml</property>
</dbServerLoader>
<queryRouter class="com.meidusa.amoeba.mysql.parser.MysqlQueryRouter">
<property name="ruleLoader">
<bean class="com.meidusa.amoeba.route.TableRuleFileLoader">
<property name="ruleFile">${amoeba.home}/conf/rule.xml</property>
<property name="functionFile">${amoeba.home}/conf/ruleFunctionMap.xml</propert
y>
</bean>
</property>
<property name="sqlFunctionFile">${amoeba.home}/conf/functionMap.xml</property>
<property name="LRUMapSize">1500</property>
<property name="defaultPool">writedb</property>
<property name="writePool">writedb</property>
<property name="readPool">myslaves</property>
<property name="needParse">true</property>
</queryRouter>
</amoeba:configuration>
启动Amoebafu服务
[root@amoeba local]# /usr/local/amoeba/bin/launcher & at com.meidusa.toolkit.net.ServerableConnectionManager.willStart(ServerableConnectionManager.java:144) at com.meidusa.toolkit.net.util.LoopingThread.run(LoopingThread.java:59) 2015-10-29 21:00:44 [INFO] Project Name=Amoeba-MySQL, PID=25948 , System shutdown .... 2015-10-29 21:01:34 [INFO] Project Name=Amoeba-MySQL, PID=25996 , starting... log4j:WARN log4j config load completed from file:/usr/local/amoeba/conf/log4j.xml 2015-10-29 21:01:34,715 INFO context.MysqlRuntimeContext - Amoeba for Mysql current versoin=5.1.45-mysql-amoeba-proxy-3.0.4-BETA log4j:WARN ip access config load completed from file:/usr/local/amoeba/conf/access_list.conf 2015-10-29 21:01:35,065 INFO net.ServerableConnectionManager - Server listening on 0.0.0.0/0.0.0.0:8066. Java HotSpot(TM) 64-Bit Server VM warning: ignoring option PermSize=16m; support was removed in 8.0 Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=96m; support was removed in 8.0 2015-10-29 21:11:40 [INFO] Project Name=Amoeba-MySQL, PID=26119 , starting... log4j:WARN log4j config load completed from file:/usr/local/amoeba/conf/log4j.xml 2015-10-29 21:11:41,446 INFO context.MysqlRuntimeContext - Amoeba for Mysql current versoin=5.1.45-mysql-amoeba-proxy-3.0.4-BETA log4j:WARN ip access config load completed from file:/usr/local/amoeba/conf/access_list.conf 2015-10-29 21:11:41,843 INFO net.ServerableConnectionManager - Server listening on 0.0.0.0/0.0.0.0:8066.
查看java进程
[root@amoeba ~]# netstat -ntlp |grep java tcp 0 0 :::8066 :::* LISTEN 26119/java
测试Amoeba负载均衡功能
[root@monitor ~]# mysql -uroot -p741616710 -h192.168.1.31 -P8066 Warning: Using a password on the command line interface can be insecure. Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 102888364 Server version: 5.1.45-mysql-amoeba-proxy-3.0.4-BETA Source distribution Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> use test1 Database changed mysql> select * from tt1; +------+---------+ | id | name | +------+---------+ | 210 | master1 | | 211 | master2 | +------+---------+ 2 rows in set (0.00 sec) mysql> select * from tt1; +------+---------+ | id | name | +------+---------+ | 210 | master1 | | 250 | slave1 | +------+---------+ 2 rows in set (0.00 sec) mysql> select * from tt1; +------+---------+ | id | name | +------+---------+ | 210 | master1 | | 209 | slave2 | +------+---------+ 2 rows in set (0.01 sec) mysql> select * from tt1; +------+---------+ | id | name | +------+---------+ | 210 | master1 | | 211 | master2 | +------+---------+ 2 rows in set (0.01 sec) mysql> select * from tt1; +------+---------+ | id | name | +------+---------+ | 210 | master1 | | 211 | master2 | +------+---------+ 2 rows in set (0.01 sec) mysql> select * from tt1; +------+---------+ | id | name | +------+---------+ | 210 | master1 | | 250 | slave1 | +------+---------+ 2 rows in set (0.01 sec)
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