Flink示例——Flink-CDC

版本信息

產品版本

Flink	1.11.1
flink-cdc-connectors	1.1.0
Java	1.8.0_231
MySQL	5.7.16

注意：官方說目前支持MySQL-5.7和8，但筆者還簡單測試過mariadb-10.0.38（對應MySQL-5.6）。包括增加、刪除、更新、聚合，目前皆可用，但不排除未知問題。

Mavan依賴

pom.xml 依賴部分

<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><!-- Flink-CDC --><dependency><groupId>com.alibaba.ververica</groupId><artifactId>flink-connector-mysql-cdc</artifactId><version>1.1.0</version></dependency></dependencies>

主從同步配置、數據準備

• 關閉MySQL服務
• 在需要被同步的MySQL節點，添加如下配置（可供參考的文檔）

[mysqld] # 前面還有其他配置 # 添加的部分 server-id = 12345 log-bin = mysql-bin # 必須為ROW binlog_format = ROW # 必須為FULL，MySQL-5.7后才有該參數 binlog_row_image = FULL expire_logs_days = 10

• 啟動MySQL服務
• 使用如下命令，可查看binlog相關變量配置

SHOW VARIABLES LIKE '%binlog%';

• 創建待測試的庫、表、數據

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');

• 創建用于同步的用戶，并給予權限（可供參考的文檔）

-- 設置擁有同步權限的用戶 CREATE USER 'flinkuser' IDENTIFIED BY 'flinkpassword'; -- 賦予同步相關權限 GRANT SELECT, RELOAD, SHOW DATABASES, REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'flinkuser';

使用Flink-CDC

• sql-client 方面，官方已經給出了示例，點擊查看
• 編碼方式，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 測試* <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);// 數據源表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" +")";// 輸出目標表String sinkDDL ="CREATE TABLE tb_sink (\n" +" name STRING,\n" +" countSum BIGINT,\n" +" PRIMARY KEY (name) NOT ENFORCED\n" +") WITH (\n" +" 'connector' = 'print'\n" +")";// 簡單的聚合處理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 yetreturn 0;}}}}

• 運行任務

簡單的測試

• 進行簡單測試，開始修改MySQL表的數據

-- SQL測試數據，對照Flink應用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;

• 執行一條SQL，查看一下Flink的結果變化

總結

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