MyCAT实现MySQL读写分离实践

MyCAT是一个的数据库中间件,基于阿里开源的cobar产品而研发,由几个有志之士的牛人共同完成并开源。提供高可用性数据分片集群,自动故障切换,高可用性 ,支持读写分离,支持MySQL双主多从,以及一主多从的模式 ,支持全局表,数据自动分片到多个节点,用于高效表关联查询 ,支持独有的基于E-R 关系的分片策略,实现了高效的表关联查询多平台支持,部署和实施简单。

今天来实践下用MyCAT实现MySQL的读写分离,1.配置MySQL端主从数据同步,2.用MyCAT实现读写分离,配置MySQL端主从数据同步不作讲解,这里详细介绍下用MyCAT实现数据读写分离

新建数据库读库和写库

分别在两个不同主机下新建两个大库,读库r和写库w,在读库r下新建3个数据库分片(db1,db2,db3),在写库w下也新建3个分片(db1,db2,db3)。

1.db1分片脚本

/*
Navicat MySQL Data Transfer
Source Server        : mysql
Source Server Version : 50527
Source Host          : localhost:3306
Source Database      : db1
Target Server Type    : MYSQL
Target Server Version : 50527
File Encoding        : 65001
Date: 2016-01-27 15:48:40
*/
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for `company`
-- ----------------------------
DROP TABLE IF EXISTS `company`;
CREATE TABLE `company` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of company
-- ----------------------------
-- ----------------------------
-- Table structure for `customer`
-- ----------------------------
DROP TABLE IF EXISTS `customer`;
CREATE TABLE `customer` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  `sharding_id` bigint(20) DEFAULT NULL,
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of customer
-- ----------------------------
INSERT INTO `customer` VALUES ('1', null);
INSERT INTO `customer` VALUES ('4', '10000');
-- ----------------------------
-- Table structure for `employee`
-- ----------------------------
DROP TABLE IF EXISTS `employee`;
CREATE TABLE `employee` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of employee
-- ----------------------------
-- ----------------------------
-- Table structure for `goods`
-- ----------------------------
DROP TABLE IF EXISTS `goods`;
CREATE TABLE `goods` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of goods
-- ----------------------------
INSERT INTO `goods` VALUES ('11');
-- ----------------------------
-- Table structure for `hotnews`
-- ----------------------------
DROP TABLE IF EXISTS `hotnews`;
CREATE TABLE `hotnews` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of hotnews
-- ----------------------------
-- ----------------------------
-- Table structure for `mycat_sequence`
-- ----------------------------
DROP TABLE IF EXISTS `mycat_sequence`;
CREATE TABLE `mycat_sequence` (
  `name` varchar(50) NOT NULL,
  `current_value` int(11) NOT NULL,
  `increment` int(11) NOT NULL DEFAULT '100',
  PRIMARY KEY (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of mycat_sequence
-- ----------------------------
INSERT INTO `mycat_sequence` VALUES ('GLOBAL', '100400', '100');
-- ----------------------------
-- Table structure for `orders`
-- ----------------------------
DROP TABLE IF EXISTS `orders`;
CREATE TABLE `orders` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  `customer_id` bigint(20) DEFAULT NULL,
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of orders
-- ----------------------------
INSERT INTO `orders` VALUES ('1', '1');
INSERT INTO `orders` VALUES ('4', '4');
-- ----------------------------
-- Table structure for `travelrecord`
-- ----------------------------
DROP TABLE IF EXISTS `travelrecord`;
CREATE TABLE `travelrecord` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of travelrecord
-- ----------------------------
INSERT INTO `travelrecord` VALUES ('1');
INSERT INTO `travelrecord` VALUES ('4');
INSERT INTO `travelrecord` VALUES ('10001');
INSERT INTO `travelrecord` VALUES ('100400');
-- ----------------------------
-- Function structure for `mycat_seq_currval`
-- ----------------------------
DROP FUNCTION IF EXISTS `mycat_seq_currval`;
DELIMITER ;;
CREATE DEFINER=`root`@`%` FUNCTION `mycat_seq_currval`(seq_name VARCHAR(50)) RETURNS varchar(64) CHARSET utf8
    DETERMINISTIC
BEGIN DECLARE retval VARCHAR(64);
SET retval="-999999999,null";
SELECT concat(CAST(current_value AS CHAR),",",CAST(increment AS CHAR)) INTO retval FROM MYCAT_SEQUENCE WHERE name = seq_name;
RETURN retval;
END
;;
DELIMITER ;
-- ----------------------------
-- Function structure for `mycat_seq_nextval`
-- ----------------------------
DROP FUNCTION IF EXISTS `mycat_seq_nextval`;
DELIMITER ;;
CREATE DEFINER=`root`@`%` FUNCTION `mycat_seq_nextval`(seq_name VARCHAR(50)) RETURNS varchar(64) CHARSET utf8
    DETERMINISTIC
BEGIN UPDATE MYCAT_SEQUENCE SET current_value = current_value + increment WHERE name = seq_name;
RETURN mycat_seq_currval(seq_name);
END
;;
DELIMITER ;
-- ----------------------------
-- Function structure for `mycat_seq_setval`
-- ----------------------------
DROP FUNCTION IF EXISTS `mycat_seq_setval`;
DELIMITER ;;
CREATE DEFINER=`root`@`%` FUNCTION `mycat_seq_setval`(seq_name VARCHAR(50),value INTEGER) RETURNS varchar(64) CHARSET utf8
    DETERMINISTIC
BEGIN UPDATE MYCAT_SEQUENCE SET current_value = value WHERE name = seq_name;
RETURN mycat_seq_currval(seq_name);
END
;;
DELIMITER ;

2.db2分片脚本

/*
Navicat MySQL Data Transfer
Source Server        : mysql
Source Server Version : 50527
Source Host          : localhost:3306
Source Database      : db2
Target Server Type    : MYSQL
Target Server Version : 50527
File Encoding        : 65001
Date: 2016-01-27 15:48:50
*/
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for `company`
-- ----------------------------
DROP TABLE IF EXISTS `company`;
CREATE TABLE `company` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of company
-- ----------------------------
-- ----------------------------
-- Table structure for `customer`
-- ----------------------------
DROP TABLE IF EXISTS `customer`;
CREATE TABLE `customer` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  `sharding_id` bigint(20) DEFAULT NULL,
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of customer
-- ----------------------------
INSERT INTO `customer` VALUES ('2', null);
INSERT INTO `customer` VALUES ('5', '10010');
-- ----------------------------
-- Table structure for `employee`
-- ----------------------------
DROP TABLE IF EXISTS `employee`;
CREATE TABLE `employee` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of employee
-- ----------------------------
-- ----------------------------
-- Table structure for `goods`
-- ----------------------------
DROP TABLE IF EXISTS `goods`;
CREATE TABLE `goods` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of goods
-- ----------------------------
INSERT INTO `goods` VALUES ('11');
-- ----------------------------
-- Table structure for `hotnews`
-- ----------------------------
DROP TABLE IF EXISTS `hotnews`;
CREATE TABLE `hotnews` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of hotnews
-- ----------------------------
INSERT INTO `hotnews` VALUES ('1');
-- ----------------------------
-- Table structure for `orders`
-- ----------------------------
DROP TABLE IF EXISTS `orders`;
CREATE TABLE `orders` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  `customer_id` bigint(20) DEFAULT NULL,
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of orders
-- ----------------------------
INSERT INTO `orders` VALUES ('2', '2');
INSERT INTO `orders` VALUES ('5', '5');
-- ----------------------------
-- Table structure for `travelrecord`
-- ----------------------------
DROP TABLE IF EXISTS `travelrecord`;
CREATE TABLE `travelrecord` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of travelrecord
-- ----------------------------
INSERT INTO `travelrecord` VALUES ('2');

3.db3分片脚本

/*
Navicat MySQL Data Transfer
Source Server        : mysql
Source Server Version : 50527
Source Host          : localhost:3306
Source Database      : db3
Target Server Type    : MYSQL
Target Server Version : 50527
File Encoding        : 65001
Date: 2016-01-27 15:48:58
*/
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for `company`
-- ----------------------------
DROP TABLE IF EXISTS `company`;
CREATE TABLE `company` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of company
-- ----------------------------
-- ----------------------------
-- Table structure for `hotnews`
-- ----------------------------
DROP TABLE IF EXISTS `hotnews`;
CREATE TABLE `hotnews` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of hotnews
-- ----------------------------
INSERT INTO `hotnews` VALUES ('2');
-- ----------------------------
-- Table structure for `travelrecord`
-- ----------------------------
DROP TABLE IF EXISTS `travelrecord`;
CREATE TABLE `travelrecord` (
  `ID` bigint(20) NOT NULL DEFAULT '0',
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of travelrecord
-- ----------------------------
INSERT INTO `travelrecord` VALUES ('3');
 

 

分别在两个读写库中建立三个分片
 
schema.xml中配置读写分离

<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://org.opencloudb/">
<schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="100">
<!-- 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" 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>
</table>
<table name="mycat_sequence" dataNode="dn1" />
</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="1000" minCon="10" balance="3"
writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100">
<heartbeat>select user()</heartbeat>
<!-- can have multi write hosts -->
<writeHost host="hostM1" url="ip1:3306" user="root" password="123456">
    <!-- can have multi read hosts -->
    <readHost host="hostS1" url="ip2:3306" user="root" password="123456" weight="1" />
</writeHost>
</dataHost>
</mycat:schema>
 

其中balance属性

负载均衡类型,目前取值有3种: 1. balance="0", 开启读写分离机制,所有读操作都发送到当前可用的writeHost上。 2. balance="1",全部的readHost和stand by writeHost参与select语句的负载均衡 3. balance="2",所有读操作都随机在writeHost、readhost上分发。 4. balance="3",所有读请求随机的分发到wiriterHost对应的readhost执行,writerHost不负担读压力

以上ip1,ip2分别填写真实地址
 
测试读写分离

启动mycat服务,

测试读数据:select * from travelrecord

可见数据是从读库中读取

测试写数据:insert into travelrecord (ID) values(88)

查看读库,没值,写库有一条88的记录

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