Flink示例——Flink-CDC

你的名字 2022-11-19 04:14 369阅读 0赞

## Flink示例——Flink-CDC ##

### 版本信息 ###

<table> 
 <thead> 
  <tr> 
   <th>产品</th> 
   <th>版本</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>Flink</td> 
   <td>1.11.1</td> 
  </tr> 
  <tr> 
   <td>flink-cdc-connectors</td> 
   <td>1.1.0</td> 
  </tr> 
  <tr> 
   <td>Java</td> 
   <td>1.8.0_231</td> 
  </tr> 
  <tr> 
   <td>MySQL</td> 
   <td>5.7.16</td> 
  </tr> 
 </tbody> 
</table>

注意：官方说目前支持MySQL-5.7和8，但笔者还简单测试过mariadb-10.0.38（对应MySQL-5.6）。包括增加、删除、更新、聚合，目前皆可用，但不排除未知问题。

### Mavan依赖 ###

#### pom.xml 依赖部分 ####

<properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <flink.version>1.11.1</flink.version>
    </properties>
    
    <dependencies>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-table-common</artifactId>
            <version>${ flink.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-java</artifactId>
            <version>${ flink.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-clients_2.11</artifactId>
            <version>${ flink.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-streaming-java_2.11</artifactId>
            <version>${ flink.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-table-api-java-bridge_2.11</artifactId>
            <version>${ flink.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-table-api-java</artifactId>
            <version>${ flink.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-table-planner-blink_2.11</artifactId>
            <version>${ flink.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-table-planner-blink_2.11</artifactId>
            <version>${ flink.version}</version>
            <type>test-jar</type>
        </dependency>
        
        <dependency>
            <groupId>com.alibaba.ververica</groupId>
            <artifactId>flink-connector-mysql-cdc</artifactId>
            <version>1.1.0</version>
        </dependency>
    
    </dependencies>

#### 主从同步配置、数据准备 ####

*  关闭MySQL服务
 *  在需要被同步的MySQL节点，添加如下配置（[可供参考的文档][Link 1]）

[mysqld]
    # 前面还有其他配置
    # 添加的部分
    server-id = 12345
    log-bin = mysql-bin
    # 必须为ROW
    binlog_format = ROW
    # 必须为FULL，MySQL-5.7后才有该参数
    binlog_row_image  = FULL
    expire_logs_days  = 10

*  启动MySQL服务
 *  使用如下命令，可查看binlog相关变量配置

SHOW VARIABLES LIKE '%binlog%';

*  创建待测试的库、表、数据

CREATE DATABASE db_inventory_cdc;
    
    CREATE TABLE tb_products_cdc(
    	id INT PRIMARY KEY AUTO_INCREMENT,
    	name VARCHAR(64),
    	description VARCHAR(128)
    );
    
    INSERT INTO tb_products_cdc
    VALUES 
    	(DEFAULT, 'zhangsan', 'aaa'),
    	(DEFAULT, 'lisi', 'bbb'),
    	(DEFAULT, 'wangwu', 'ccc');

*  创建用于同步的用户，并给予权限（可供参考的文档）

-- 设置拥有同步权限的用户
    CREATE USER 'flinkuser' IDENTIFIED BY 'flinkpassword';
    -- 赋予同步相关权限
    GRANT SELECT, RELOAD, SHOW DATABASES, REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'flinkuser';

### 使用Flink-CDC ###

*  sql-client 方面，官方已经给出了示例，[点击查看][Link 2]
 *  编码方式，方便提交jar包，示例如下

import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
    import org.apache.flink.table.api.EnvironmentSettings;
    import org.apache.flink.table.api.TableResult;
    import org.apache.flink.table.api.bridge.java.StreamTableEnvironment;
    import org.apache.flink.table.planner.factories.TestValuesTableFactory;
    
    /** * Description: Flink-CDC 测试 * <br/> * Date: 2020/9/16 14:03 * * @author ALion */
    public class FlinkCDCSQLTest { 
    
        public static void main(String[] args) throws Exception { 
            EnvironmentSettings fsSettings = EnvironmentSettings.newInstance()
                    .useBlinkPlanner()
                    .inStreamingMode()
                    .build();
            StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
            env.setParallelism(1);
            StreamTableEnvironment tableEnv = StreamTableEnvironment.create(env, fsSettings);
            
    		// 数据源表
            String sourceDDL =
                    "CREATE TABLE mysql_binlog (\n" +
                    " id INT NOT NULL,\n" +
                    " name STRING,\n" +
                    " description STRING\n" +
                    ") WITH (\n" +
                    " 'connector' = 'mysql-cdc',\n" +
                    " 'hostname' = 'localhost',\n" +
                    " 'port' = '3306',\n" +
                    " 'username' = 'flinkuser',\n" +
                    " 'password' = 'flinkpassword',\n" +
                    " 'database-name' = 'db_inventory_cdc',\n" +
                    " 'table-name' = 'tb_products_cdc'\n" +
                    ")";
            // 输出目标表
            String sinkDDL =
                    "CREATE TABLE tb_sink (\n" +
                    " name STRING,\n" +
                    " countSum BIGINT,\n" +
                    " PRIMARY KEY (name) NOT ENFORCED\n" +
                    ") WITH (\n" +
                    " 'connector' = 'print'\n" +
                    ")";
            // 简单的聚合处理
            String transformSQL =
                    "INSERT INTO tb_sink " +
                    "SELECT name, COUNT(1) " +
                    "FROM mysql_binlog " +
                    "GROUP BY name";
                    
            tableEnv.executeSql(sourceDDL);
            tableEnv.executeSql(sinkDDL);
            TableResult result = tableEnv.executeSql(transformSQL);
            
    		// 等待flink-cdc完成快照
            waitForSnapshotStarted("tb_sink");
            result.print();
            
            result.getJobClient().get().cancel().get();
        }
    
        private static void waitForSnapshotStarted(String sinkName) throws InterruptedException { 
            while (sinkSize(sinkName) == 0) { 
                Thread.sleep(100);
            }
        }
    
        private static int sinkSize(String sinkName) { 
            synchronized (TestValuesTableFactory.class) { 
                try { 
                    return TestValuesTableFactory.getRawResults(sinkName).size();
                } catch (IllegalArgumentException e) { 
                    // job is not started yet
                    return 0;
                }
            }
        }
    
    }

*  运行任务

### 简单的测试 ###

*  进行简单测试，开始修改MySQL表的数据

-- SQL测试数据，对照Flink应用
    
    INSERT INTO tb_products_cdc VALUE(DEFAULT, 'lisi', 'ddd');
    
    DELETE FROM tb_products_cdc WHERE id=4;
    
    UPDATE tb_products_cdc SET name='wangwu' WHERE id=2;

*  执行一条SQL，查看一下Flink的结果变化

[Link 1]: https://debezium.io/documentation/reference/1.2/connectors/mysql.html#enable-the-mysql-binlog-for-cdc_debezium
[Link 2]: https://github.com/ververica/flink-cdc-connectors