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/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/txhttp://www.springframework.org/schema/tx/spring-tx.xsdhttp://www.dangdang.com/schema/ddframe/rdbhttp://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idlong 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/
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