Sharding +SpringBoot+Mybatis 无迁移的分库分表方案

动态分库分表

1.方案简述

动态分库+取模分表的方式，解决扩容时数据迁移，分表数据热点问题。

根据数据库配置的规则来计算会路由到哪个数据库里面去。例：我对user表进行了分库分表。当user数据量小于30我就只插入db0这个数据库。大于30小于60我就插入db1这个数据库。

id	start	end	db_name
1	1	30	db0
2	31	60	db1

如果数据量超过60，我就再建一个数据库db2，并且在这个规则表里加一条数据就行了

id	start	end	db_name
1	1	30	db0
2	31	60	db1
3	61	90	db2

2.pom.xml

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		
		<dependency>
			<groupId>org.mybatis.spring.boot</groupId>
			<artifactId>mybatis-spring-boot-starter</artifactId>
			<version>2.0.1</version>
		</dependency>
		
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
		</dependency>
		
		<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>druid-spring-boot-starter</artifactId>
			<version>1.1.16</version>
		</dependency>
		
		<dependency>
			<groupId>org.apache.shardingsphere</groupId>
			<artifactId>sharding-jdbc-spring-boot-starter</artifactId>
			<version>4.0.0-RC1</version>
		</dependency>
		
		<!-- <dependency>
			<groupId>io.shardingjdbc</groupId>
			<artifactId>sharding-jdbc-spring-boot-starter</artifactId>
			<version>2.0.0.M3</version>
		</dependency> -->
  </dependencies>

3.配置文件

server.port=8084

mybatis.config-location=classpath:META-INF/mybatis-config.xml

spring.shardingsphere.datasource.names=master0,master0slave,master1,master1slave


# 数据源
spring.shardingsphere.datasource.master0.type=com.alibaba.druid.pool.DruidDataSource
spring.shardingsphere.datasource.master0.driver-class-name=com.mysql.jdbc.Driver
spring.shardingsphere.datasource.master0.url=jdbc:mysql://localhost:3306/ds_0?characterEncoding=utf-8
spring.shardingsphere.datasource.master0.username=root
spring.shardingsphere.datasource.master0.password=0490218292

spring.shardingsphere.datasource.master0slave.type=com.alibaba.druid.pool.DruidDataSource
spring.shardingsphere.datasource.master0slave.driver-class-name=com.mysql.jdbc.Driver
spring.shardingsphere.datasource.master0slave.url=jdbc:mysql://localhost:3306/ds_0_slave?characterEncoding=utf-8
spring.shardingsphere.datasource.master0slave.username=root
spring.shardingsphere.datasource.master0slave.password=0490218292

spring.shardingsphere.datasource.master1.type=com.alibaba.druid.pool.DruidDataSource
spring.shardingsphere.datasource.master1.driver-class-name=com.mysql.jdbc.Driver
spring.shardingsphere.datasource.master1.url=jdbc:mysql://localhost:3306/ds_1?characterEncoding=utf-8
spring.shardingsphere.datasource.master1.username=root
spring.shardingsphere.datasource.master1.password=0490218292

spring.shardingsphere.datasource.master1slave.type=com.alibaba.druid.pool.DruidDataSource
spring.shardingsphere.datasource.master1slave.driver-class-name=com.mysql.jdbc.Driver
spring.shardingsphere.datasource.master1slave.url=jdbc:mysql://localhost:3306/ds_1_slave?characterEncoding=utf-8
spring.shardingsphere.datasource.master1slave.username=root
spring.shardingsphere.datasource.master1slave.password=0490218292


# 分表配置
spring.shardingsphere.sharding.tables.user.actual-data-nodes=ds$->{0..1}.user_$->{0..2}
spring.shardingsphere.sharding.tables.user.table-strategy.inline.sharding-column=id
spring.shardingsphere.sharding.tables.user.table-strategy.inline.algorithm-expression=user_$->{id % 3}


# 分库配置
spring.shardingsphere.sharding.default-database-strategy.standard.sharding-column=id
spring.shardingsphere.sharding.default-database-strategy.standard.precise-algorithm-class-name=com.cxytiandi.sharding.algorithm.MyPreciseShardingAlgorithm


# 读写分离
spring.shardingsphere.sharding.master-slave-rules.ds0.master-data-source-name=master0
spring.shardingsphere.sharding.master-slave-rules.ds0.slave-data-source-names=master0slave

spring.shardingsphere.sharding.master-slave-rules.ds1.master-data-source-name=master1
spring.shardingsphere.sharding.master-slave-rules.ds1.slave-data-source-names=master1slave

spring.shardingsphere.props.sql.show=true

4.自定义的分片算法

/**
 * 自定义分片算法
 * 
 * @author mmc
 *
 */
public class MyPreciseShardingAlgorithm implements PreciseShardingAlgorithm<Long> {

	
	@Override
	public String doSharding(Collection<String> availableTargetNames, PreciseShardingValue<Long> shardingValue) {
		Long id = shardingValue.getValue();
		ShareDbService shareDbService = SpringUtil.getBean(ShareDbService.class);
		List<String> dbs = shareDbService.getDbById(id);
		if(dbs!=null&&dbs.size()>0){
			return dbs.get(0);
		}
		throw new IllegalArgumentException("找不到数据库："+id);
	}

}

源码地址：https://github.com/mmcLine/sharding