寫在前面
??Mycat作為獨立的數據庫中間件，我們只需要進行相關的配置，就可以非常方便的幫我們實現水平切分、垂直切分、讀寫分離等功能，但Mysql的主從復制需要我們通過其它方式實現。這里假設我們已經搭建好相關的環境，下面就開始我們的實踐吧！
準備環境
- Mysql(Version : 5.7)主從環境搭建
- 對應數據庫建立（以下例子中要建的數據庫是：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，別忘了重啟Mycat，如果有異常出現，請通過查看logs目錄下的日志文件進行排查。
項目搭建（SpringBoot + JPA）
準備：首次建表，設置application.yml中的spring.jpa.hibernate.ddl-auto屬性為：create（JPA自動建表解決方案，使用update的話在連接mycat的時候會報找不到表的錯誤）。為保證數據不被丟失，在建表之后可以更改為：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);
}
項目測試
- 測試添加
@Test
public void testAdd() {
for (long i = 0; i < 30; i++) {
User user = new User();
user.setId(i);
user.setName("張三" + i);
user.setGender(i % 2 == 0 ? 0 : 1);
userDao.save(user);
Student student = new Student();
student.setId(System.currentTimeMillis() + i);
student.setName("張三學生" + i);
student.setUserId(i);
studentDao.save(student);
}
}
測試結果：數據按id取模的方式劃分到了兩個數據庫中，同時從庫同步了主庫的數據
- 測試模糊查詢+分頁
@Test
public void testFind() {
Pageable pageable = new PageRequest(0, 10, Sort.Direction.DESC, "id");
List<User> userList = userDao.findByNameLike("%張三2%", pageable).getContent();
userList.forEach(System.out::println);
Pageable pageable2 = new PageRequest(0, 10, Sort.Direction.DESC, "userId");
List<Student> studentList = studentDao.findByNameLike("%張三學生1%", pageable2).getContent();
studentList.forEach(System.out::println);
}
測試結果：按照模糊匹配及id降序的方式輸出結果
測試結果：讀操作都走了從庫
- 刪除及修改請自行測試
參考鏈接
Mycat官網
Mycat從零開始
Mycat權威指南
GitHub：Mycat-Server
Wiki：Mycat-Server
Issues：Mycat-Server
mysql中間件研究（Atlas，Cobar，TDDL）
mysql中間件研究（Atlas，Cobar，TDDL，Mycat，Heisenberg，Oceanus，Vitess，OneProxy）
