What is MyCat?

Look at the introduction on the official website.

Main characteristics:

Download and install:

Download to the official website according to the system type: http://mycat.io/

Unzip the downloaded file in the following directory:

Brief description of each catalog:

Enter the bin directory, open the DOS window as an administrator, and execute the commands separately:

mycat install

mycat start

So you can start mycat.

Core configuration

Example

For the first time, the easiest way to understand mycat is to start with examples. For example, this example combines mysql to complete the database and tables of data, and to expand horizontally.

First of all, we need to prepare several mysql servers. Through the construction of docker, how can we refer to the internet? The general steps are as follows:

If there is no accident, you can connect, because I installed docker through the local virtual machine, default port 192.168.99.100. Now start three containers based on the downloaded image and modify different ports.

Connect the above three databases through client tools, and build tables:

Create a database: TESTDB

Establishment of table:

CREATE TABLE `employee` (
  `id` int(11) NOT NULL,
  `name` varchar(56) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

1. Modify the server.xml configuration file

    <user name="root" defaultAccount="true">
        <property name="password">123456</property>

        <!-- Use this name when connecting, for example jdbc:mysql://localhost:8066/TESTDB -->
        <property name="schemas">TESTDB</property>
    </user>

2. Modify schema.xml

    <schema name="TESTDB" checkSQLschema="true" sqlMaxLimit="100">

        <table name="employee" primaryKey="ID" dataNode="dn1,dn2,dn3"  rule="mod-long" />

    </schema>
    <!-- name Node name, corresponding to; dataHost: Real database configuration; database: Database table configuration -->
    <dataNode name="dn1" dataHost="host1" database="TESTDB" />
    <dataNode name="dn2" dataHost="host2" database="TESTDB" />
    <dataNode name="dn3" dataHost="host3" database="TESTDB" />

    <dataHost name="host1" maxCon="1000" minCon="10" balance="0" writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100">
        <heartbeat>select 1</heartbeat>
        <writeHost host="hostS1" url="192.168.99.100:32768" user="root" password="123456" />
    </dataHost>
    <dataHost name="host2" maxCon="1000" minCon="10" balance="0" writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100">
        <heartbeat>select 1</heartbeat>
        <writeHost host="hostS2" url="192.168.99.100:32769" user="root" password="123456" />
    </dataHost>
    <dataHost name="host3" maxCon="1000" minCon="10" balance="0" writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100">
        <heartbeat>select 1</heartbeat>
        <writeHost host="hostS3" url="192.168.99.100:39770" user="root" password="123456" />
    </dataHost>

3. Modify rule.xml

This completes the configuration of mycat. Because of the modification of the configuration, we restart MYCAT and enter bin, mycat restart.

test

Since mybatis-plus+springboot projects were used before, all of them used this:

application-mycat.properties:

mybatis-plus.mapper-locations=classpath*:com/sucl/sbmp/*/mapper/**Mapper.xml
mybatis-plus.type-aliases-package=com.sucl.sbmp.*.entity
mybatis-plus.global-config.refresh=true
#mybatis-plus.global-config.db-config.db-type=mysql
mybatis-plus.configuration.map-underscore-to-camel-case=true
mybatis-plus.configuration.cache-enabled=false


mp.datasource.driver-class-name=com.mysql.jdbc.Driver
mp.datasource.url=jdbc:mysql://localhost:8066/TESTDB?useUnicode=true&useSSL=false&characterEncoding=utf8
mp.datasource.username=root
mp.datasource.password=123456
mp.datasource.validation-query=select '1'
mp.datasource.testOnBorrow=true

Entities:

@Data
public class Employee {

    @TableId(type = IdType.INPUT)
    private long id;

    @TableField(value = "name")
    private String name;
}

mapper:

public interface EmployeeMapper extends BaseMapper<Employee> {

}

service:

@Service
@Transactional
public class EmployeeServiceImpl extends ServiceImpl<EmployeeMapper,Employee> implements EmployeeService {

}

Test:

@ActiveProfiles("mycat")
@RunWith(SpringRunner.class)
@SpringBootTest
public class SbmpTest {
    @Autowired
    private EmployeeService employeeService;

    @Transactional
    @Rollback(false)
    @Test
    public void save(){
        List<Employee> employees = new ArrayList<>();
        for(int i=0;i<100;i++){
            Employee employee = new Employee();
            employee.setId(i);
            employee.setName("name"+i);
            employees.add(employee);
        }
        employeeService.saveBatch(employees);
    }

    @Test
    public void get(){
        List<Employee> employees = employeeService.list(null);
        employees.stream().forEach(System.out::println);
    }

}

Two methods are executed to insert data into three databases according to id:

When querying, you can view all the data in the three tables.