读写分离

读写分离

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sharing-jdbc实现读写分离及分库分表

需求：

分库：按业务线business_id将不同业务线的订单存储在不同的数据库上；

分表：按user_id字段将不同用户的订单存储在不同的表上，为方便直接用非分片字段order_id查询，可使用基因法；

读写分离：为缓解主库的压力，读操作访问从库；

库表SQL

sharing-jdbc实现读写分离及分库分表-LMLPHP
-- 主库

CREATE DATABASE `database_103`;

CREATE DATABASE `database_112`;

-- 从库

CREATE DATABASE `database_slave_103`;

CREATE DATABASE `database_slave_112`;

--每个库上分别建立如下表

CREATE TABLE `t_order_0` (

  `id` bigint(20) NOT NULL,

  `order_id` bigint(20) NOT NULL,

  `user_id` bigint(20) NOT NULL,

  `business_id` bigint(20) NOT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `t_order_1` (

  `id` bigint(20) NOT NULL,

  `order_id` bigint(20) NOT NULL,

  `user_id` bigint(20) NOT NULL,

  `business_id` bigint(20) NOT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `t_order_2` (

  `id` bigint(20) NOT NULL,

  `order_id` bigint(20) NOT NULL,

  `user_id` bigint(20) NOT NULL,

  `business_id` bigint(20) NOT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `t_order` VALUES (1,1,112);

CREATE TABLE `t_order_3` (

  `id` bigint(20) NOT NULL,

  `order_id` bigint(20) NOT NULL,

  `user_id` bigint(20) NOT NULL,

  `business_id` bigint(20) NOT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8;
sharing-jdbc实现读写分离及分库分表-LMLPHP

pom.xml

sharing-jdbc实现读写分离及分库分表-LMLPHP
        <!-- sharding-jdbc -->

        <dependency>

            <groupId>com.dangdang</groupId>

            <artifactId>sharding-jdbc-core</artifactId>

            <version>1.4.2</version>

        </dependency>

        <dependency>

            <groupId>com.dangdang</groupId>

            <artifactId>sharding-jdbc-config-spring</artifactId>

            <version>1.4.0</version>

        </dependency>
sharing-jdbc实现读写分离及分库分表-LMLPHP

spring-database.xml

sharing-jdbc实现读写分离及分库分表-LMLPHP
<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

       xmlns:tx="http://www.springframework.org/schema/tx"

       xmlns:rdb="http://www.dangdang.com/schema/ddframe/rdb"

       xsi:schemaLocation="http://www.springframework.org/schema/beans

                        http://www.springframework.org/schema/beans/spring-beans.xsd

                        http://www.springframework.org/schema/tx

                        http://www.springframework.org/schema/tx/spring-tx.xsd

                        http://www.dangdang.com/schema/ddframe/rdb

                        http://www.dangdang.com/schema/ddframe/rdb/rdb.xsd">

    <bean id="database_112" class="com.alibaba.druid.pool.DruidDataSource" init-method="init"

          destroy-method="close">

        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>

        <property name="url" value="${jdbc.url.112}"></property>

        <property name="username" value="${jdbc.username.112}"></property>

        <property name="password" value="${jdbc.password.112}"></property>

        <property name="maxActive" value="100"/>

        <property name="initialSize" value="50"/>

        <property name="maxWait" value="60000"/>

        <property name="minIdle" value="5"/>

    </bean>

    <bean id="database_slave_112" class="com.alibaba.druid.pool.DruidDataSource" init-method="init"

          destroy-method="close">

        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>

        <property name="url" value="${jdbc.url.slave.112}"></property>

        <property name="username" value="${jdbc.username.slave.112}"></property>

        <property name="password" value="${jdbc.password.slave.112}"></property>

        <property name="maxActive" value="100"/>

        <property name="initialSize" value="50"/>

        <property name="maxWait" value="60000"/>

        <property name="minIdle" value="5"/>

    </bean>

    <bean id="database_103" class="com.alibaba.druid.pool.DruidDataSource" init-method="init"

          destroy-method="close">

        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>

        <property name="url" value="${jdbc.url.103}"></property>

        <property name="username" value="${jdbc.username.103}"></property>

        <property name="password" value="${jdbc.password.103}"></property>

        <property name="maxActive" value="100"/>

        <property name="initialSize" value="50"/>

        <property name="maxWait" value="60000"/>

        <property name="minIdle" value="5"/>

    </bean>

    <bean id="database_slave_103" class="com.alibaba.druid.pool.DruidDataSource" init-method="init"

          destroy-method="close">

        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>

        <property name="url" value="${jdbc.url.slave.103}"></property>

        <property name="username" value="${jdbc.username.slave.103}"></property>

        <property name="password" value="${jdbc.password.slave.103}"></property>

        <property name="maxActive" value="100"/>

        <property name="initialSize" value="50"/>

        <property name="maxWait" value="60000"/>

        <property name="minIdle" value="5"/>

    </bean>

    <!--mybatis-->

    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">

        <property name="mapperLocations" value="classpath:xmlmapper/*.xml"/>

        <property name="dataSource" ref="shardingDataSource"/>

        <!-- 配置Mybatis配置文件 -->

        <property name="configLocation" value="classpath:/mybatis/mybatis-config.xml"/>

    </bean>

    <bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">

        <constructor-arg index="0" ref="sqlSessionFactory"/>

    </bean>

    <!-- 注解Mapper scanner -->

    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">

        <property name="basePackage" value="com.lc.sharding.mybatismapper"/>

        <property name="sqlSessionTemplateBeanName" value="sqlSession"/>

    </bean>

    <!-- 事务-->

    <bean id="txManager"

          class="org.springframework.jdbc.datasource.DataSourceTransactionManager">

        <property name="dataSource" ref="shardingDataSource"/>

    </bean>

    <tx:annotation-driven transaction-manager="txManager"/>

    <!--读写分离-->

    <rdb:master-slave-data-source id="rbb_112" master-data-source-ref="database_112"

                                  slave-data-sources-ref="database_slave_112"/>

    <rdb:master-slave-data-source id="rbb_103" master-data-source-ref="database_103"

                                  slave-data-sources-ref="database_slave_103"/>

    <!--分库策略-->

    <rdb:strategy id="databaseShardingStrategy" sharding-columns="business_id"

                  algorithm-expression="rbb_${business_id.longValue()}"/>

    <!--分表策略-->

    <rdb:strategy id="tableShardingStrategy" sharding-columns="user_id,order_id"

                  algorithm-class="com.lc.sharding.algorithm.MultipleKeysTableShardingAlgorithmImpl"/>

    <rdb:data-source id="shardingDataSource">

        <rdb:sharding-rule data-sources="rbb_112,rbb_103">

            <rdb:table-rules>

                <rdb:table-rule logic-table="t_order" actual-tables="t_order_${0..3}" database-strategy="databaseShardingStrategy"

                                table-strategy="tableShardingStrategy"/>

            </rdb:table-rules>

        </rdb:sharding-rule>

        <rdb:props>

            <prop key="metrics.enable">true</prop>

            <prop key="sql.show">true</prop>

        </rdb:props>

    </rdb:data-source>

</beans
sharing-jdbc实现读写分离及分库分表-LMLPHP

基因法多列分片

sharing-jdbc实现读写分离及分库分表-LMLPHP
public class MultipleKeysTableShardingAlgorithmImpl implements MultipleKeysTableShardingAlgorithm {

    public Collection<String> doSharding(Collection<String> tableNames, Collection<ShardingValue<?>> shardingValues) {

        List<String> shardingSuffix = new ArrayList<String>();

        long partId = 0;

        for (ShardingValue value : shardingValues) {

            if (value.getColumnName().equals("user_id")) {

                partId = ((Long) value.getValue()) % 4;

                break;

            } else if (value.getColumnName().equals("order_id")) {

                partId = ((Long) value.getValue()) % 4;

                break;

            }

        }

        for (String name : tableNames) {

            if (name.endsWith(partId + "")) {

                shardingSuffix.add(name);

                return shardingSuffix;

            }

        }

        return shardingSuffix;

    }

}
sharing-jdbc实现读写分离及分库分表-LMLPHP

什么是基因法分片？

在订单数据oid生成时，order_id末端加入分片基因，让同一个user_id下的所有订单都含有相同基因，落在同一个表上。

资料：https://mp.weixin.qq.com/s/PCzRAZa9n4aJwHOX-kAhtA

根据user_id生成order_id:

sharing-jdbc实现读写分离及分库分表-LMLPHP
    public long bulidOrderId(long userId) {

        //取用户id后4位

        userId = userId & 15;

        //先取60位唯一id

        long uniqueId = this.nextId();

        //唯一id左移4位、拼接userId后4位

        return (uniqueId << 4) | userId;

    }
sharing-jdbc实现读写分离及分库分表-LMLPHP
this.nextId();//使用雪花算法生成60位分布式唯一id：1位符号位+41位时间戳+5位workId+5位datacenterId+6位序列号+4位基因片

小结

数据分片：

  • 支持分库+分表；
  • 可支持 = ， BETWEEN，IN等多维度分片，也支持多分片键共用；
  • 支持聚合，分组，排序，分页，关联等复杂查询语句；
  • 分片灵活，支持多分片键共用，支持inline表达式；
  • 基于Hint的强制路由；
  • 支持分布式主键

读写分离：

  • 支持一主多从的读写分离；
  • 支持分库分表与读写分离共同使用
  • 支持分布式生成全局主键。

柔性事务：

  • 最大努力到达型事务

分布式治理：

  • 支持配置中心，可动态修改
  • 支持客户端熔断和失效转移

引用：http://shardingsphere.io/

05-11 11:13
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