mycat分库规则sharding-by-murmur一致性hash

  murmur算法是将字段进行hash后分发到不同的数据库,字段类型支持int和varchar.
1.rule.xml

<tableRule name="sharding-by-murmur-userid">
        <rule>
                <columns>userid</columns>
                <algorithm>murmur</algorithm>
        </rule>
</tableRule>

<function name="murmur"
class="io.mycat.route.function.PartitionByMurmurHash">
<property name="seed">0</property><!-- 默认是0 -->
<property name="count">6</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 -->
<!-- <property name="weightMapFile">weightMapFile</property> 节点的权重，没有指定权重的节点默认是1。以properties文件
的格式填写，以从0开始到count-1的整数值也就是节点索引为key，以节点权重值为值。所有权重值必须是正整数，否则以1代替 -->
<!-- <property name="bucketMapPath">/etc/mycat/bucketMapPath</property>
用于测试时观察各物理节点与虚拟节点的分布情况，如果指定了这个属性，会把虚拟节点的murmur hash值与物理节点的映
射按行输出到这个文件，没有默认值，如果不指定，就不会输出任何东西 -->
</function>

name="count" 根据分库的个数设置,我这里6个分库


2.schema.xml配置文件

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

        <schema name="logdb" checkSQLschema="false" sqlMaxLimit="100">
          <table name="tb_log_t" primaryKey="ID" autoIncrement="true" dataNode="dn1,dn2,dn3,dn4,dn5,dn6" rule="mod-long" />
          <table name="tb_user_t" dataNode="dn1,dn2,dn3,dn4,dn5,dn6" rule="sharding-by-intfile-provcode" />
          <table name="tb_user_detail_t" dataNode="dn1,dn2,dn3,dn4,dn5,dn6" rule="auto-sharding-long-userid" />
          <table name="tb_user_murmur_t" dataNode="dn1,dn2,dn3,dn4,dn5,dn6" rule="sharding-by-murmur" />
          <table name="tb_user_murmur_string_t" dataNode="dn1,dn2,dn3,dn4,dn5,dn6" rule="sharding-by-murmur-userid" />
        </schema>
        <schema name="coss03" checkSQLschema="false" sqlMaxLimit="100" dataNode="dnoss03"/>
        <dataNode name="dn1" dataHost="localhost1" database="log01" />
        <dataNode name="dn2" dataHost="localhost1" database="log02" />
        <dataNode name="dn3" dataHost="localhost1" database="log03" />
        <dataNode name="dn4" dataHost="localhost1" database="log04" />
        <dataNode name="dn5" dataHost="localhost1" database="log05" />
        <dataNode name="dn6" dataHost="localhost1" database="log06" />
        <dataNode name="dnoss03" dataHost="localhost1" database="oss03" />
        <dataHost name="localhost1" 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="192.168.56.141:3306" user="root"
                                   password="mysql">
                        <!-- can have multi read hosts -->
                        <readHost host="hostS2" url="192.168.56.142:3306" user="root" password="mysql" />
                </writeHost>
        </dataHost>
</mycat:schema>

3.创建表


CREATE TABLE `tb_user_murmur_string_t` (
  `userid` varchar(32) NOT NULL,
  `name` varchar(64) DEFAULT NULL,
  `createtime` datetime DEFAULT CURRENT_TIMESTAMP,
  `moditytime` datetime DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`userid`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;


写入数据
insert into tb_user_murmur_string_t(userid,name) values('user002','name002');
insert into tb_user_murmur_string_t(userid,name) values('user003','name003');
insert into tb_user_murmur_string_t(userid,name) values('user004','name004');
insert into tb_user_murmur_string_t(userid,name) values('user005','name005');
insert into tb_user_murmur_string_t(userid,name) values('user006','name006');
insert into tb_user_murmur_string_t(userid,name) values('user007','name007');
insert into tb_user_murmur_string_t(userid,name) values('user008','name008');
insert into tb_user_murmur_string_t(userid,name) values('user009','name009');
insert into tb_user_murmur_string_t(userid,name) values('user010','name010');

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