MyCat如何实现MySQL双主一从读写分离
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1）配置server.xml
<user name="root" defaultAccount="true"> <property name="password">mysql</property> <property name="schemas">TESTDB</property> <!-- 表级 DML 权限设置 --> <!-- <privileges check="false"> <schema name="TESTDB" dml="0110" > <table name="tb01" dml="0000"></table> <table name="tb02" dml="1111"></table> </schema> </privileges> --> </user>
配置用户root，密码为mysql，对TESTDB具有权限
2）配置schema.xml
<schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="100" dataNode="dn1"> </schema> <!-- <dataNode name="dn1$0-743" dataHost="localhost1" database="db$0-743" /> --> <dataNode name="dn1" dataHost="localhost1" database="test" /> <dataNode name="dn2" dataHost="localhost1" database="dedecms" /> <dataNode name="dn3" dataHost="localhost1" database="xcredit" /> <!--<dataNode name="dn4" dataHost="sequoiadb1" database="SAMPLE" /> <dataNode name="jdbc_dn1" dataHost="jdbchost" database="db1" /> <dataNode name="jdbc_dn2" dataHost="jdbchost" database="db2" /> <dataNode name="jdbc_dn3" dataHost="jdbchost" database="db3" /> --> <dataHost name="localhost1" maxCon="1000" minCon="10" balance="1" writeType="0" dbType="mysql" dbDriver="native" switchType="1" slaveThreshold="100"> <heartbeat>select user()</heartbeat> <!-- can have multi write hosts --> <writeHost host="master1" url="192.168.8.57:3306" user="root" password="mysql"> <!-- can have multi read hosts --> <readHost host="slave" url="192.168.8.59:3306" user="root" password="mysql" /> </writeHost> <writeHost host="master2" url="192.168.8.58:3306" user="root" password="mysql" />
schema标签：schema name属性指定逻辑库名，dataNode属性指定下边的dataNode
dataNode标签：dataHost指定下边的dataHost，database指定具体的database
dataHost标签：balance指的负载均衡类型，switchType指的是切换的模式
balance指的负载均衡类型，目前的取值有4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stand by writeHost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。
4. balance="3"，所有读请求随机的分发到wiriterHost对应的readhost执行，writerHost不负担读压力
switchType指的是切换的模式，目前的取值也有4种：
1. switchType='-1' 表示不自动切换
2. switchType='1' 默认值，表示自动切换
3. switchType='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
4. switchType='3'基于MySQL galary cluster的切换机制（适合集群）（1.4.1），心跳语句为 show status like 'wsrep%'。
3）启动mycat，并观察日志
/usr/local/mycat/bin/mycat start
[root@oneproxy logs]# tail -f wrapper.log STATUS | wrapper | 2018/08/25 10:32:39 | --> Wrapper Started as Daemon STATUS | wrapper | 2018/08/25 10:32:40 | Launching a JVM... INFO | jvm 1 | 2018/08/25 10:32:40 | Wrapper (Version 3.2.3) http://wrapper.tanukisoftware.org INFO | jvm 1 | 2018/08/25 10:32:40 | Copyright 1999-2006 Tanuki Software, Inc. All Rights Reserved. INFO | jvm 1 | 2018/08/25 10:32:40 | INFO | jvm 1 | 2018/08/25 10:32:41 | log4j:WARN No appenders could be found for logger (io.mycat.memory.MyCatMemory). INFO | jvm 1 | 2018/08/25 10:32:41 | log4j:WARN Please initialize the log4j system properly. INFO | jvm 1 | 2018/08/25 10:32:41 | log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info. INFO | jvm 1 | 2018/08/25 10:32:41 | MyCAT Server startup successfully. see logs in logs/mycat.log
4）在mycat服务器登录mysql
mysql -uroot -pmysql -P8066 -h292.168.8.63
mysql> show databases;
+----------+
| DATABASE |
+----------+
| TESTDB |
+----------+
5）测试读写分离
mysql> use TESTDB; mysql> create table t4(hostname1 varchar(12),hostname2 varchar(12),hostname3 varchar(12)); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname); mysql> mysql> insert into t4 values(@@hostname,@@hostname,@@hostname);
mysql> select * from t4; +-----------+-----------+-----------+ | hostname1 | hostname2 | hostname3 | +-----------+-----------+-----------+ | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | | master1 | master1 | master1 | +-----------+-----------+-----------+ 64 rows in set (0.00 sec)
插入的数据都是从master1插入的，通过查询mycat日志，发现所有的查询全部分发到了slave节点。
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