　　mycat 入门教程

　　之前已经对mycat的配置进行了详细记得介绍，下面就是一个mycat分库的小例子

schema.xml配置

<?xml version="1.0"?>

<!DOCTYPE mycat:schema SYSTEM "schema.dtd">

<mycat:schema xmlns:mycat="http://io.mycat/">

    <schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="">

        <!-- auto sharding by id (long) -->

        <table name="travelrecord" dataNode="dn1,dn2,dn3" rule="auto-sharding-long" />

        <!-- global table is auto cloned to all defined data nodes ,so can join

            with any table whose sharding node is in the same data node -->

        <table name="company" primaryKey="ID" type="global" dataNode="dn1,dn2,dn3" />

        <table name="goods" primaryKey="ID" type="global" dataNode="dn1,dn2" />

        <!-- random sharding using mod sharind rule -->

        <table name="hotnews" primaryKey="ID" autoIncrement="true" dataNode="dn1,dn2,dn3"

               rule="mod-long" />

        <table name="employee" primaryKey="ID" dataNode="dn1,dn2"

               rule="sharding-by-intfile" />

        <table name="customer" primaryKey="ID" dataNode="dn1,dn2"

               rule="sharding-by-intfile">

            <childTable name="orders" primaryKey="ID" joinKey="customer_id"

                        parentKey="id">

                <childTable name="order_items" joinKey="order_id"

                            parentKey="id" />

            </childTable>

            <childTable name="customer_addr" primaryKey="ID" joinKey="customer_id"

                        parentKey="id" />

        </table>

    </schema>

    <dataNode name="dn1" dataHost="localhost1" database="db1" />

    <dataNode name="dn2" dataHost="localhost1" database="db2" />

    <dataNode name="dn3" dataHost="localhost1" database="db3" />

    <dataHost name="localhost1" maxCon="" minCon="" balance=""

              writeType="" dbType="mysql" dbDriver="native" switchType=""  slaveThreshold="">

        <heartbeat>select user()</heartbeat>

        <!-- can have multi write hosts -->

        <writeHost host="hostM1" url="localhost:3306" user="root"

                   password="">

            <!-- can have multi read hosts -->

            <readHost host="hostS2" url="192.168.1.200:3306" user="root" password="xxx" />

        </writeHost>

        <writeHost host="hostS1" url="localhost:3316" user="root"

                   password="" />

    </dataHost>

</mycat:schema>

表简介

　　　　　travelrecord ：

            分库dn1,dn2,dn3

            分库规则:app_user_id

                M=;

                -500M=;    #-500万 dn1

                500M-1000M=;    #500万-1000万 dn2

                1000M-1500M=；

        company:全局表

            分库dn1,dn2,dn3

        goods:全局表

            分库dn1,dn2

        hotnews ：自增id

            分库dn1,dn2,dn3

            分库规则:mod-long，根据节点id/节点数，进行平均分配

        employee：

            分库：dn1,dn2，根据state状态分库

                =；    #   sharding_id= dn1

                =；    #   sharding_id=10010 dn2

        customer：主表

            分库：dn1,dn2，根据state状态分库

                =；    #   sharding_id= dn1

                10010=；    #   sharding_id=10010 dn2

        customer_addr：子表

            关联字段：customer_id

链接MYSQL 创建数据库

mysql> CREATE DATABASE `db1` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;

Query OK, 1 row affected

mysql> CREATE DATABASE `db2` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;
Query OK, 1 row affected

mysql> CREATE DATABASE `db3` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;
Query OK, 1 row affected

链接Mycat

mysql -h127.0.0.1 -uroot -p123456 -P8066

插入表

mysql> show mydb；

Database changed
<!-- 根据id进行分段分库 -->
mysql> create table travelrecord (id bigint not null primary key,user_id varchar(),traveldate DATE, fee decimal,app_user_id int);

Query OK,  rows affected (0.05 sec)

mysql> insert into travelrecord(id,user_id,traveldate,fee,app_user_id)  values(,'Victor',,,);

Query OK,  row affected (0.09 sec)

mysql> insert into travelrecord(id,user_id,traveldate,fee,app_user_id)  values(,'Job',,,);

Query OK,  row affected (0.00 sec)

mysql> insert into travelrecord(id,user_id,traveldate,fee,app_user_id)  values(,'Slow',,,);

Query OK,  row affected (0.00 sec)

结果：dn1,dn2,dn3分别建表，三条数据根据id分库

<!-- 全局表，每个库中保存全部数据 -->

mysql> create table company (id bigint not null primary key,user_id varchar(100),traveldate DATE, fee decimal,days int);
Query OK, 0 rows affected (0.08 sec)

mysql> insert into company(id,user_id,traveldate,fee,days) values(1,'Victor',20160101,100,10);
Query OK, 1 row affected (0.01 sec)

mysql> insert into company(id,user_id,traveldate,fee,days) values(2,'Job',20160102,100,10);
Query OK, 1 row affected (0.00 sec)

结果：每个库中保存全部数据。

<!-- 分片存储，平均分配到每个库中 -->

mysql> create table hotnews (id bigint not null primary key,user_id varchar(100),traveldate DATE, fee decimal,days int);
Query OK, 0 rows affected (0.06 sec)

mysql> insert into hotnews(id,user_id,traveldate,fee,days) values(1,'Victor',20160101,100,10);
Query OK, 1 row affected (0.01 sec)

mysql> insert into hotnews(id,user_id,traveldate,fee,days) values(2,'Job',20160102,100,10);
Query OK, 1 row affected (0.00 sec)

mysql> insert into hotnews(id,user_id,traveldate,fee,days) values(3,'Job',20160102,100,10);
Query OK, 1 row affected (0.00 sec)

mysql> insert into hotnews(id,user_id,traveldate,fee,days) values(4,'Job',20160102,100,10);
Query OK, 1 row affected (0.00 sec)

mysql> insert into hotnews(id,user_id,traveldate,fee,days) values(5,'Job',20160102,100,10);
Query OK, 1 row affected (0.00 sec)

mysql> insert into hotnews(id,user_id,traveldate,fee,days) values(6,'Job',20160102,100,10);
Query OK, 1 row affected (0.00 sec)

结果：根据id平均分配储存到每个库中

<!-- 枚举法：根据配置字段识别分别分配到每个库中 -->

mysql> create table employee(id bigint not null primary key,name varchar(100),sharding_id int);
Query OK, 0 rows affected (0.04 sec)

mysql> insert into employee(id,name,sharding_id) values(1,'Victor',10000);
Query OK, 1 row affected (0.05 sec)

mysql> insert into employee(id,name,sharding_id) values(2,'Victor',10010);
Query OK, 1 row affected (0.00 sec)

mysql> insert into employee(id,name,sharding_id) values(3,'Victor',10010);
Query OK, 1 row affected (0.00 sec)

mysql> insert into employee(id,name,sharding_id) values(4,'employee',10010);
Query OK, 1 row affected (0.00 sec)

mysql> insert into employee(id,name,sharding_id) values(5000001,'employee',10000);
Query OK, 1 row affected (0.00 sec)

<!-- 关联表：主表：customer 字表customer_addr->

mysql> create table customer(id bigint not null primary key,name varchar(100),sharding_id int);
Query OK, 0 rows affected (0.04 sec)

mysql> insert into customer(id,name,sharding_id) values(1,'Victor',10000);
Query OK, 1 row affected (0.00 sec)

mysql> insert into customer(id,name,sharding_id) values(2,'Job',10010);
Query OK, 1 row affected (0.00 sec)

mysql> create table customer_addr(id bigint not null primary key,addr varchar(100),customer_id int);
Query OK, 0 rows affected (0.05 sec)

mysql> insert into customer_addr(id,addr,customer_id) values(1,'home',1);
Query OK, 1 row affected (0.20 sec)

mysql> insert into customer_addr(id,addr,customer_id) values(2,'this',2);
Query OK, 1 row affected (0.41 sec)

总结：

关于MyCAT的配置其实是蛮简单的，最主要的是熟悉各配置文件的规则。以上用户名，密码，如何分库，都是在配置文件中定义的，后续，有时间再一一详表。

关于配置文件，conf目录下主要以下三个需要熟悉。

server.xml是Mycat服务器参数调整和用户授权的配置文件

schema.xml是逻辑库定义和表以及分片定义的配置文件

rule.xml是分片规则的配置文件