Mycat的学习

1.安装，要先安装JDK，要注意是64位版，最好是tar.gz的（在官网下载下来是.gz结尾，直接将名字改成tar.gz。。。）

2.涉及3个配置文件

server.xml 用于设置登陆mycat的账号密码以及登陆后能看到的虚拟表

    <user name="root">
        <property name="password">123456</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>

schema.xml 用来设置mycat中的虚拟表，以及所用到的规则和正式用到的数据库

<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://io.mycat/">

    <schema name="TESTDB" checkSQLschema="ture" sqlMaxLimit="100">
        <table name="t1" dataNode="dn1,dn2" rule="auto-sharding-long" />     虚拟表，那个ture是固定的，limit是指查询条数，允许dn1,dn2两个数据库连接，rule来自于rule.xml
    </schema>
    
    <schema name="d1" checkSQLschema="ture" sqlMaxLimit="100">
        <table name="t1" dataNode="dn1,dn2" rule="auto-sharding-long" />
    </schema>
    
    <!-- <dataNode name="dn1$0-743" dataHost="localhost1" database="db$0-743"
        /> -->
    <dataNode name="dn1" dataHost="localhost1" database="db1" />
    <dataNode name="dn2" dataHost="localhost2" database="db2" />              连接的两个真实数据库
    <!--<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="0"              真实数据库的连接
              writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100">   
        <heartbeat>select user()</heartbeat>
        <!-- can have multi write hosts -->
        <writeHost host="hostM1" url="192.168.189.128:3306" user="tang"
                   password="123123">
    </dataHost>
    


    <dataHost name="localhost2" maxCon="1000" minCon="10" balance="0"
              writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100">
        <heartbeat>select user()</heartbeat>
        <!-- can have multi write hosts -->
        <writeHost host="hostM1" url="192.168.189.128:3306" user="tang"
                   password="123123">
    </dataHost>
</mycat:schema>

rule.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE mycat:rule SYSTEM "rule.dtd">
<mycat:rule xmlns:mycat="http://io.mycat/">
    <tableRule name="auto-sharding-long">
        <rule>
            <columns>prov</columns>
            <algorithm>hash-int</algorithm>
        </rule>
    </tableRule>

    <function name="hash-int"
        class="io.mycat.route.function.PartitionByMurmurHash">
        <property name="mapFile">auto-sharding-long.txt</property>         设定规则来自这个文件
        <property name="type">1</property><!-- 要分片的数据库节点数量，必须指定，否则没法分片 -->
        <property name="virtualBucketTimes">160</property><!-- 一个实际的数据库节点被映射为这么多虚拟节点，默认是160倍，也就是虚拟节点数是物理节点数的160倍 -->
    </function>
</mycat:rule>

这样就可以实现分布式储存了