mycat 分片的策略

目的：有 user 和 t_order 两张数据表，表 user 的数据全部存放在 db1_zhang 中，表 t_order 的数据按 id 对 2 取模分别存放在 db1_zhang 和 db2_zhang 中。

1. 本地启动 2 个 MySQL 实例，端口分别设置为 3306 和 3307

3306 实例

create database db1_zhang;
use db1_zhang;
create table user(id int, name varchar(32));
create table t_order(id int, name varchar(32));

3307 实例

create database db2_zhang;
use db2_zhang;
create table t_order(id int, name varchar(32));

2. 配置 mycat，启动

server.xml

<user name="mycat">
    <property name="password">mycat</property>
    <property name="schemas">TESTDB</property>
</user>

rule.xml

<tableRule name="rule1">
    <rule>
        <columns>id</columns>
        <algorithm>mod-long</algorithm>
    </rule>
</tableRule>
 
<function name="mod-long" class="io.mycat.route.function.PartitionByMod">
    <!-- how many data nodes -->
    <property name="count">2</property>
</function>

schema.xml

<!-- name="TESTDB" 与 server.xml中的 TESTDB 设置一致 -->
<schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="100">
    <table name="user" primaryKey="id"  dataNode="node1" />
    <table name="t_order" primaryKey="id" dataNode="node1,node2" rule="rule1" />
</schema>  
 
<dataNode name="node1" dataHost="host1" database="db1_zhang" />
<dataNode name="node2" dataHost="host2" database="db2_zhang" />  
 
<!-- 物理机的 url -->
<dataHost name="host1" maxCon="1000" minCon="10" balance="0" writeType="0" dbType="mysql" dbDriver="native">
    <heartbeat>select user()</heartbeat>
    <writeHost host="server1" url="127.0.0.1:3306" user="root" password="123456"/>
</dataHost>
<dataHost name="host2" maxCon="1000" minCon="10" balance="0" writeType="0" dbType="mysql" dbDriver="native">
    <heartbeat>select user()</heartbeat>
    <writeHost host="server1" url="127.0.0.1:3307" user="root" password="123456"/>
</dataHost> 

3. 连接到 mycat，测试

mysql -umycat -pmycat -h127.0.0.1 -P8066 -DTESTDB

insert into user values(1, 'zhang'),(2, 'wang');
insert into t_order(id, name) values(1, 'book'),(2, 'phone'),(3, 'clothes');