前言

项目初期没有强大的 DBA, 随着用户增加, 订单表越来越大, MySQL 的主机负载一直下不来, 导致吞吐降低

• GitHub 地址: https://github.com/lmxdawn/sharding-spring-boot-mybatis-example

订单业务分析

表结构:

CREATE TABLE `order_0` (`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `order_id` bigint(20) unsigned NOT NULL,
  `uid` bigint(20) unsigned NOT NULL,
  `money` int(11) NOT NULL,
  `status` tinyint(3) unsigned NOT NULL DEFAULT '0',
  `create_time` datetime NOT NULL,
  `modified_time` datetime NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `uk_order_id` (`order_id`),
  KEY `idx_uid` (`uid`)
) ENGINE=InnoDB AUTO_INCREMENT=20 DEFAULT CHARSET=utf8mb4

问题分析:

由于是单 key 业务, 只需要通过 uid 来查询, 则按照 uid 来做分表因子

分库中间件

经过一些权衡, 还是准备使用 shardingsphere , 社区活跃度也比较不错

开始使用

jdk 8 , shardingsphere 版本 4.0.0-RC2

路由规则

• 分 2 个库, 一个库 4 张表
• 路由计算, 库: uid % 2 个库
• 路由计算, 表: uid / 2 个库 % 4 张表 (取商后再取余, 这里要注意取商有小数需要强转为整型后再取余)

uid	uid % 2 (库)	uid / 2 % 4 (表)
1	1	0
2	0	1
3	1	1
4	0	2
5	1	2
6	0	3
7	1	3
8	0	0

MySQL 结构

• 先创建两个库, db0 和 db1
• 把下面的结构分别导入两个库中

CREATE TABLE `order_0` (`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `order_id` bigint(20) unsigned NOT NULL,
  `uid` bigint(20) unsigned NOT NULL,
  `money` int(11) NOT NULL,
  `status` tinyint(3) unsigned NOT NULL DEFAULT '0',
  `create_time` datetime NOT NULL,
  `modified_time` datetime NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `uk_order_id` (`order_id`),
  KEY `idx_uid` (`uid`)
) ENGINE=InnoDB AUTO_INCREMENT=20 DEFAULT CHARSET=utf8mb4
CREATE TABLE `order_1` (`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `order_id` bigint(20) unsigned NOT NULL,
  `uid` bigint(20) unsigned NOT NULL,
  `money` int(11) NOT NULL,
  `status` tinyint(3) unsigned NOT NULL DEFAULT '0',
  `create_time` datetime NOT NULL,
  `modified_time` datetime NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `uk_order_id` (`order_id`),
  KEY `idx_uid` (`uid`)
) ENGINE=InnoDB AUTO_INCREMENT=20 DEFAULT CHARSET=utf8mb4
CREATE TABLE `order_2` (`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `order_id` bigint(20) unsigned NOT NULL,
  `uid` bigint(20) unsigned NOT NULL,
  `money` int(11) NOT NULL,
  `status` tinyint(3) unsigned NOT NULL DEFAULT '0',
  `create_time` datetime NOT NULL,
  `modified_time` datetime NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `uk_order_id` (`order_id`),
  KEY `idx_uid` (`uid`)
) ENGINE=InnoDB AUTO_INCREMENT=20 DEFAULT CHARSET=utf8mb4
CREATE TABLE `order_3` (`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `order_id` bigint(20) unsigned NOT NULL,
  `uid` bigint(20) unsigned NOT NULL,
  `money` int(11) NOT NULL,
  `status` tinyint(3) unsigned NOT NULL DEFAULT '0',
  `create_time` datetime NOT NULL,
  `modified_time` datetime NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `uk_order_id` (`order_id`),
  KEY `idx_uid` (`uid`)
) ENGINE=InnoDB AUTO_INCREMENT=20 DEFAULT CHARSET=utf8mb4

spring boot 的 pom.xml

<!--web-->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

<!-- 自动生成 GET SET-->
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
</dependency>

<!-- 连接池 -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.12</version>
</dependency>

<!--MySQL-->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>

<!--mybatis -->
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.3.2</version>
</dependency>

<dependency>
    <groupId>org.apache.shardingsphere</groupId>
    <artifactId>sharding-jdbc-spring-boot-starter</artifactId>
    <version>4.0.0-RC2</version>
</dependency>

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>

spring boot 的 application-sharding-databases.properties

spring.shardingsphere.datasource.names=db0,db1

spring.shardingsphere.datasource.db0.type=com.alibaba.druid.pool.DruidDataSource
spring.shardingsphere.datasource.db0.driver-class-name=com.mysql.cj.jdbc.Driver
spring.shardingsphere.datasource.db0.url=jdbc:mysql://localhost:3306/db0?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai&zeroDateTimeBehavior=convertToNull
spring.shardingsphere.datasource.db0.username=root
spring.shardingsphere.datasource.db0.password=root

spring.shardingsphere.datasource.db1.type=com.alibaba.druid.pool.DruidDataSource
spring.shardingsphere.datasource.db1.driver-class-name=com.mysql.cj.jdbc.Driver
spring.shardingsphere.datasource.db1.url=jdbc:mysql://localhost:3306/db1?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai&zeroDateTimeBehavior=convertToNull
spring.shardingsphere.datasource.db1.username=root
spring.shardingsphere.datasource.db1.password=root

# 是否显示 SQL 语句
spring.shardingsphere.props.sql.show=true

# 配置数据库和表
spring.shardingsphere.sharding.tables.order.actual-data-nodes=db$->{0..1}.order_$->{0..1}
# 配置根据哪个字段选择数据库
spring.shardingsphere.sharding.tables.order.database-strategy.inline.sharding-column=uid
# 配置选择哪个数据库的规则
spring.shardingsphere.sharding.tables.order.database-strategy.inline.algorithm-expression=db$->{uid % 2}
# 配置选择根据哪个字段选择表
spring.shardingsphere.sharding.tables.order.table-strategy.inline.sharding-column=uid
# 配置选择哪个表的规则
spring.shardingsphere.sharding.tables.order.table-strategy.inline.algorithm-expression=order_$->{(Integer)(uid / 2) % 4}

启动 java web 程序

需要注意, 查询订单详情需要带上用户 uid, 用来路由到对应的库和表

• 创建订单: http://localhost:8080/order/create?uid=1
• 订单列表:http://localhost:8080/order/lists?uid=1&page=1&limit=1
• 订单详情:http://localhost:8080/order/detail?uid=1&orderId=373591446294364161

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