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

-- 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;

pom.xml

        <!-- 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>

spring-database.xml

<?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

基因法多列分片

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;
    }
}

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:

    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;
    }

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/