mycat——分片规则（2）

配置

<dataHost name="localhost1" maxCon="1000" minCon="10" balance="1" writeType="0" dbType="mysql" dbDriver="native">
    <heartbeat>select user()</heartbeat>
    <!-- can have multi write hosts -->
    <writeHost host="hostM1" url="localhost:3306" user="root" password="123456">
    	<!-- can have multi read hosts -->
    	<readHost host="hostS1" url="localhost2:3306" user="root" password="123456" weight="1" />
    </writeHost>
</dataHost>

<dataHost name="localhost1" maxCon="1000" minCon="10" balance="1" writeType="0" dbType="mysql" dbDriver="native">
    <heartbeat>select user()</heartbeat>
    <!-- can have multi write hosts -->
    <writeHost host="hostM1" url="localhost:3306" user="root" password="123456"></writeHost>
    <writeHost host="hostS1" url="localhost:3307" user="root" password="123456"></writeHost>
</dataHost>

第一种当写挂了读不可用，第二种可以继续使用，事务内部的一切操作都会走写节点，所以读
操作不要加事务，如果读延时较大，使用根据主从延时的读写分离，或者强制走写节点

--强制走从：
/*!mycat:db_type=slave*/ select * from travelrecord
/*#mycat:db_type=slave*/ select * from travelrecord
--强制走写：
/*#mycat:db_type=master*/ select * from travelrecord
/*!mycat:db_type=master*/ select *