写在前面
Mycat作为独立的数据库中间件，我们只需要进行相关的配置，就可以非常方便的帮我们实现水平切分、垂直切分、读写分离等功能，但Mysql的主从复制需要我们通过其它方式实现。这里假设我们已经搭建好相关的环境，下面就开始我们的实践吧！
准备环境
- Mysql(Version : 5.7)主从环境搭建
- 对应数据库建立（以下例子中要建的数据库是：master1mycat 和 master2mycat）
配置server.xml
<user name="mysqlmycat">
<property name="password">mysqlmycat</property>
<property name="schemas">mysqlmycats</property>
</user>
配置schema.xml
<schema name="mysqlmycats" checkSQLschema="false" sqlMaxLimit="100">
<table name="tb_user" dataNode="mydn1,mydn2" rule="user-mod-long" />
<table name="tb_student" dataNode="mydn1,mydn2" rule="student-mod-long" />
</schema>
<dataNode name="mydn1" dataHost="myhost1" database="master1mycat" />
<dataNode name="mydn2" dataHost="myhost2" database="master2mycat" />
<dataHost name="myhost1" maxCon="100" minCon="10" balance="3" writeType="0" dbType="mysql" dbDriver="native">
<heartbeat>select user()</heartbeat>
<writeHost host="hostM1" url="localhost:3306" user="root" password="xxx">
<readHost host="hostS1" url="localhost:3307" user="root" password="xxx"/>
</writeHost>
</dataHost>
<dataHost name="myhost2" maxCon="100" minCon="10" balance="3" writeType="0" dbType="mysql" dbDriver="native">
<heartbeat>select user()</heartbeat>
<writeHost host="hostM2" url="localhost:3308" user="root" password="xxx" >
<readHost host="hostS2" url="localhost:3309" user="root" password="xxx"/>
</writeHost>
</dataHost>
配置rule.xml
<tableRule name="user-mod-long">
<rule>
<columns>id</columns>
<algorithm>mod-long</algorithm>
</rule>
</tableRule>
<tableRule name="student-mod-long">
<rule>
<columns>user_id</columns>
<algorithm>mod-long</algorithm>
</rule>
</tableRule>
<function name="mod-long" class="io.mycat.route.function.PartitionByMod">
<property name="count">2</property>
</function>
修改了配置文件后，别忘了重启Mycat，如果有异常出现，请通过查看logs目录下的日志文件进行排查。
项目搭建（SpringBoot + JPA）
-
准备：首次建表，设置application.yml中的spring.jpa.hibernate.ddl-auto属性为：create（JPA自动建表解决方案，使用update的话在连接mycat的时候会报找不到表的错误）。为保证数据不被丢失，在建表之后可以更改为：update
-
添加application.yml：
spring:
jpa:
show-sql: true
hibernate:
ddl-auto: update
naming:
strategy: org.hibernate.cfg.ImprovedNamingStrategy
properties:
hibernate:
dialect: org.hibernate.dialect.MySQL5Dialect
datasource:
url: jdbc:mysql://localhost:8066/mysqlmycats?characterEncoding=UTF-8&useSSL=false&autoReconnect=true&rewriteBatchedStatements=true
username: mysqlmycat
password: mysqlmycat
- 添加User Entity
@Entity
@Table(name = "tb_user")
@Data
public class User {
@Id
private Long id;
private String name;
private Integer gender;
}
- 添加Student Entity
@Entity
@Table(name = "tb_student")
@Data
public class Student {
@Id
private Long id;
private String name;
@Column(unique = true)
private Long userId;
}
- 添加UserDao
public interface UserDao extends JpaRepository<User, Long> {
Page<User> findByNameLike(String name, Pageable pageable);
}
- 添加StudentDao
public interface StudentDao extends JpaRepository<Student, Long> {
Page<User> findByNameLike(String name, Pageable pageable);
}
项目测试
- 测试添加
@Test
public void testAdd() {
for (long i = 0; i < 30; i++) {
User user = new User();
user.setId(i);
user.setName("张三" + i);
user.setGender(i % 2 == 0 ? 0 : 1);
userDao.save(user);
Student student = new Student();
student.setId(System.currentTimeMillis() + i);
student.setName("张三学生" + i);
student.setUserId(i);
studentDao.save(student);
}
}
测试结果：数据按id取模的方式划分到了两个数据库中，同时从库同步了主库的数据
- 测试模糊查询+分页
@Test
public void testFind() {
Pageable pageable = new PageRequest(0, 10, Sort.Direction.DESC, "id");
List<User> userList = userDao.findByNameLike("%张三2%", pageable).getContent();
userList.forEach(System.out::println);
Pageable pageable2 = new PageRequest(0, 10, Sort.Direction.DESC, "userId");
List<Student> studentList = studentDao.findByNameLike("%张三学生1%", pageable2).getContent();
studentList.forEach(System.out::println);
}
测试结果：按照模糊匹配及id降序的方式输出结果
测试结果：读操作都走了从库
- 删除及修改请自行测试
文章已授权获得转载，原文地址：https://blog.mariojd.cn/mycat-practice-based-mysql.html
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