---

前言

最近在学习Flink CDC相关的知识，作为小白就从官方的教学示例开始动手，本篇文章分享的是官方教程实践–基于 Flink CDC 构建 MySQL 和 Postgres 的 Streaming ETL。

---

1.环境准备

（1）docker-compose部署mysql、postgres、es、kibana

在yaml所在目录下执行以下命令：

docker-compose up -d

部署yaml文件内容具体如下：

version: '2.1'
services:postgres:image: debezium/example-postgres:1.1ports:- "5432:5432"environment:- POSTGRES_DB=postgres- POSTGRES_USER=postgres- POSTGRES_PASSWORD=postgresmysql:image: debezium/example-mysql:1.1ports:- "3306:3306"environment:- MYSQL_ROOT_PASSWORD=123456- MYSQL_USER=mysqluser- MYSQL_PASSWORD=mysqlpwelasticsearch:image: elastic/elasticsearch:7.6.0environment:- cluster.name=docker-cluster- bootstrap.memory_lock=true- "ES_JAVA_OPTS=-Xms512m -Xmx512m"- discovery.type=single-nodeports:- "9200:9200"- "9300:9300"ulimits:memlock:soft: -1hard: -1nofile:soft: 65536hard: 65536kibana:image: elastic/kibana:7.6.0ports:- "5601:5601"

（2）部署flink

• 下载flink安装包并解压
  flink下载地址：https://archive.apache.org/dist/flink/flink-1.13.2/flink-1.13.2-bin-scala_2.11.tgz
• 下载以下依赖包并放在flink安装目录的lib包中
  https://repo.maven.apache.org/maven2/org/apache/flink/flink-sql-connector-elasticsearch7_2.11/1.13.2/flink-sql-connector-elasticsearch7_2.11-1.13.2.jar
  https://repo1.maven.org/maven2/com/ververica/flink-sql-connector-mysql-cdc/2.1.0/flink-sql-connector-mysql-cdc-2.1.0.jar
  https://repo1.maven.org/maven2/com/ververica/flink-sql-connector-postgres-cdc/2.1.0/flink-sql-connector-postgres-cdc-2.1.0.jar
  注意：官方文档上使用snapshot jar包，编译GitHub上master分支后将snapshot jar包放到flink安装目录的lib包后再做后续的测试会出现以下报错：
  
  日志中会出现以下报错信息：日志显示无法执行SQL语句，然后在等待job初始化时发生错误，最后重试次数用完，flink也挂了

2022-10-25 15:17:29,917 INFO  org.apache.flink.configuration.Configuration                 [] - Config uses fallback configuration key 'jobmanager.rpc.address' instead of key 'rest.address'
2022-10-25 15:18:32,472 WARN  org.apache.flink.table.client.cli.CliClient                  [] - Could not execute SQL statement.
org.apache.flink.table.client.gateway.SqlExecutionException: Could not execute SQL statement.at org.apache.flink.table.client.gateway.local.LocalExecutor.executeModifyOperations(LocalExecutor.java:228) ~[flink-sql-client_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.cli.CliClient.callInserts(CliClient.java:518) ~[flink-sql-client_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.cli.CliClient.callInsert(CliClient.java:507) ~[flink-sql-client_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.cli.CliClient.callOperation(CliClient.java:409) ~[flink-sql-client_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.cli.CliClient.lambda$executeStatement$0(CliClient.java:327) [flink-sql-client_2.11-1.13.2.jar:1.13.2]at java.util.Optional.ifPresent(Optional.java:159) ~[?:1.8.0_281]at org.apache.flink.table.client.cli.CliClient.executeStatement(CliClient.java:327) [flink-sql-client_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.cli.CliClient.executeInteractive(CliClient.java:297) [flink-sql-client_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.cli.CliClient.executeInInteractiveMode(CliClient.java:221) [flink-sql-client_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.SqlClient.openCli(SqlClient.java:151) [flink-sql-client_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.SqlClient.start(SqlClient.java:95) [flink-sql-client_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.SqlClient.startClient(SqlClient.java:187) [flink-sql-client_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.SqlClient.main(SqlClient.java:161) [flink-sql-client_2.11-1.13.2.jar:1.13.2]
Caused by: org.apache.flink.table.api.TableException: Failed to execute sqlat org.apache.flink.table.api.internal.TableEnvironmentImpl.executeInternal(TableEnvironmentImpl.java:777) ~[flink-table-blink_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.api.internal.TableEnvironmentImpl.executeInternal(TableEnvironmentImpl.java:742) ~[flink-table-blink_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.gateway.local.LocalExecutor.lambda$executeModifyOperations$4(LocalExecutor.java:226) ~[flink-sql-client_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.gateway.context.ExecutionContext.wrapClassLoader(ExecutionContext.java:90) ~[flink-sql-client_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.gateway.local.LocalExecutor.executeModifyOperations(LocalExecutor.java:226) ~[flink-sql-client_2.11-1.13.2.jar:1.13.2]... 12 more
Caused by: org.apache.flink.util.FlinkException: Failed to execute job 'insert-into_default_catalog.default_database.enriched_orders'.at org.apache.flink.streaming.api.environment.StreamExecutionEnvironment.executeAsync(StreamExecutionEnvironment.java:1970) ~[flink-dist_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.planner.delegation.ExecutorBase.executeAsync(ExecutorBase.java:55) ~[flink-table-blink_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.api.internal.TableEnvironmentImpl.executeInternal(TableEnvironmentImpl.java:759) ~[flink-table-blink_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.api.internal.TableEnvironmentImpl.executeInternal(TableEnvironmentImpl.java:742) ~[flink-table-blink_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.gateway.local.LocalExecutor.lambda$executeModifyOperations$4(LocalExecutor.java:226) ~[flink-sql-client_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.gateway.context.ExecutionContext.wrapClassLoader(ExecutionContext.java:90) ~[flink-sql-client_2.11-1.13.2.jar:1.13.2]at org.apache.flink.table.client.gateway.local.LocalExecutor.executeModifyOperations(LocalExecutor.java:226) ~[flink-sql-client_2.11-1.13.2.jar:1.13.2]... 12 more
Caused by: java.lang.RuntimeException: Error while waiting for job to be initializedat org.apache.flink.client.ClientUtils.waitUntilJobInitializationFinished(ClientUtils.java:160) ~[flink-dist_2.11-1.13.2.jar:1.13.2]at org.apache.flink.client.deployment.executors.AbstractSessionClusterExecutor.lambda$execute$2(AbstractSessionClusterExecutor.java:82) ~[flink-dist_2.11-1.13.2.jar:1.13.2]at org.apache.flink.util.function.FunctionUtils.lambda$uncheckedFunction$2(FunctionUtils.java:73) ~[flink-dist_2.11-1.13.2.jar:1.13.2]at java.util.concurrent.CompletableFuture.uniApply(CompletableFuture.java:616) ~[?:1.8.0_281]at java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:591) ~[?:1.8.0_281]at java.util.concurrent.CompletableFuture$Completion.exec(CompletableFuture.java:457) ~[?:1.8.0_281]at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289) ~[?:1.8.0_281]at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1067) ~[?:1.8.0_281]at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1703) ~[?:1.8.0_281]at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:172) ~[?:1.8.0_281]
Caused by: java.util.concurrent.ExecutionException: org.apache.flink.runtime.concurrent.FutureUtils$RetryException: Could not complete the operation. Number of retries has been exhausted.at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357) ~[?:1.8.0_281]at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1908) ~[?:1.8.0_281]at org.apache.flink.client.deployment.executors.AbstractSessionClusterExecutor.lambda$null$0(AbstractSessionClusterExecutor.java:83) ~[flink-dist_2.11-1.13.2.jar:1.13.2]at org.apache.flink.client.ClientUtils.waitUntilJobInitializationFinished(ClientUtils.java:144) ~[flink-dist_2.11-1.13.2.jar:1.13.2]at org.apache.flink.client.deployment.executors.AbstractSessionClusterExecutor.lambda$execute$2(AbstractSessionClusterExecutor.java:82) ~[flink-dist_2.11-1.13.2.jar:1.13.2]at org.apache.flink.util.function.FunctionUtils.lambda$uncheckedFunction$2(FunctionUtils.java:73) ~[flink-dist_2.11-1.13.2.jar:1.13.2]at java.util.concurrent.CompletableFuture.uniApply(CompletableFuture.java:616) ~[?:1.8.0_281]at java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:591) ~[?:1.8.0_281]at java.util.concurrent.CompletableFuture$Completion.exec(CompletableFuture.java:457) ~[?:1.8.0_281]at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289) ~[?:1.8.0_281]at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1067) ~[?:1.8.0_281]at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1703) ~[?:1.8.0_281]at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:172) ~[?:1.8.0_281]
Caused by: org.apache.flink.runtime.concurrent.FutureUtils$RetryException: Could not complete the operation. Number of retries has been exhausted.

---

2.准备数据

2.1 MySQL

docker-compose exec mysql mysql -uroot -p123456

mysql> CREATE DATABASE mydb;
Query OK, 1 row affected (0.01 sec)mysql> USE mydb;
Database changedmysql> CREATE TABLE products (->   id INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY,->   name VARCHAR(255) NOT NULL,->   description VARCHAR(512)-> );
Query OK, 0 rows affected (0.05 sec)mysql> ALTER TABLE products AUTO_INCREMENT = 101;
Query OK, 0 rows affected (0.02 sec)
Records: 0  Duplicates: 0  Warnings: 0mysql> INSERT INTO products-> VALUES (default,"scooter","Small 2-wheel scooter"),->        (default,"car battery","12V car battery"),->        (default,"12-pack drill bits","12-pack of drill bits with sizes ranging from #40 to #3"),->        (default,"hammer","12oz carpenter's hammer"),->        (default,"hammer","14oz carpenter's hammer"),->        (default,"hammer","16oz carpenter's hammer"),->        (default,"rocks","box of assorted rocks"),->        (default,"jacket","water resistent black wind breaker"),->        (default,"spare tire","24 inch spare tire");
Query OK, 9 rows affected (0.01 sec)
Records: 9  Duplicates: 0  Warnings: 0mysql> select * from products;
+-----+--------------------+---------------------------------------------------------+
| id  | name               | description                                             |
+-----+--------------------+---------------------------------------------------------+
| 101 | scooter            | Small 2-wheel scooter                                   |
| 102 | car battery        | 12V car battery                                         |
| 103 | 12-pack drill bits | 12-pack of drill bits with sizes ranging from #40 to #3 |
| 104 | hammer             | 12oz carpenter's hammer                                 |
| 105 | hammer             | 14oz carpenter's hammer                                 |
| 106 | hammer             | 16oz carpenter's hammer                                 |
| 107 | rocks              | box of assorted rocks                                   |
| 108 | jacket             | water resistent black wind breaker                      |
| 109 | spare tire         | 24 inch spare tire                                      |
+-----+--------------------+---------------------------------------------------------+
9 rows in set (0.00 sec)mysql> CREATE TABLE orders (->   order_id INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY,->   order_date DATETIME NOT NULL,->   customer_name VARCHAR(255) NOT NULL,->   price DECIMAL(10, 5) NOT NULL,->   product_id INTEGER NOT NULL,->   order_status BOOLEAN NOT NULL -- Whether order has been placed-> ) AUTO_INCREMENT = 10001;
Query OK, 0 rows affected (0.04 sec)mysql> show tables;
+----------------+
| Tables_in_mydb |
+----------------+
| orders         |
| products       |
+----------------+
2 rows in set (0.00 sec)mysql> INSERT INTO orders-> VALUES (default, '2020-07-30 10:08:22', 'Jark', 50.50, 102, false),->        (default, '2020-07-30 10:11:09', 'Sally', 15.00, 105, false),->        (default, '2020-07-30 12:00:30', 'Edward', 25.25, 106, false);
Query OK, 3 rows affected (0.01 sec)
Records: 3  Duplicates: 0  Warnings: 0mysql> select * from orders;
+----------+---------------------+---------------+----------+------------+--------------+
| order_id | order_date          | customer_name | price    | product_id | order_status |
+----------+---------------------+---------------+----------+------------+--------------+
|    10001 | 2020-07-30 10:08:22 | Jark          | 50.50000 |        102 |            0 |
|    10002 | 2020-07-30 10:11:09 | Sally         | 15.00000 |        105 |            0 |
|    10003 | 2020-07-30 12:00:30 | Edward        | 25.25000 |        106 |            0 |
+----------+---------------------+---------------+----------+------------+--------------+
3 rows in set (0.01 sec)

2.2 postgres

docker-compose exec postgres psql -h localhost -U postgres

postgres=# CREATE TABLE shipments (
postgres(#   shipment_id SERIAL NOT NULL PRIMARY KEY,
postgres(#   order_id SERIAL NOT NULL,
postgres(#   origin VARCHAR(255) NOT NULL,
postgres(#   destination VARCHAR(255) NOT NULL,
postgres(#   is_arrived BOOLEAN NOT NULL
postgres(# );
CREATE TABLE
postgres=# ALTER SEQUENCE public.shipments_shipment_id_seq RESTART WITH 1001;
ALTER SEQUENCE
postgres=# ALTER TABLE public.shipments REPLICA IDENTITY FULL;
ALTER TABLE
postgres=# INSERT INTO shipments
postgres-# VALUES (default,10001,'Beijing','Shanghai',false),
postgres-#        (default,10002,'Hangzhou','Shanghai',false),
postgres-#        (default,10003,'Shanghai','Hangzhou',false);
INSERT 0 3
postgres=# select * from shipments;shipment_id | order_id |  origin  | destination | is_arrived
-------------+----------+----------+-------------+------------1001 |    10001 | Beijing  | Shanghai    | f1002 |    10002 | Hangzhou | Shanghai    | f1003 |    10003 | Shanghai | Hangzhou    | f
(3 rows)

---

3.启动flink和flink sql client

3.1启动flink

sunxi@bogon flink-1.13.2 % ./bin/start-cluster.sh
Starting cluster.
Starting standalonesession daemon on host bogon.
Starting taskexecutor daemon on host bogon.

访问flink web UI:http://localhost:8081/#/overview

3.2启动flink SQL client

./bin/sql-client.sh

---

4.在flink SQL CLI中使用flink DDL创建表

4.1开启checkpoint

Flink SQL> SET execution.checkpointing.interval = 3s;
[INFO] Session property has been set.

4.2对于数据库中的表 products, orders, shipments， 使用 Flink SQL CLI 创建对应的表，用于同步这些底层数据库表的数据

• MySQL

Flink SQL> CREATE TABLE products (
>     id INT,
>     name STRING,
>     description STRING,
>     PRIMARY KEY (id) NOT ENFORCED
>   ) WITH (
>     'connector' = 'mysql-cdc',
>     'hostname' = 'localhost',
>     'port' = '3306',
>     'username' = 'root',
>     'password' = '123456',
>     'database-name' = 'mydb',
>     'table-name' = 'products'
>   );
[INFO] Execute statement succeed.Flink SQL> CREATE TABLE orders (
>    order_id INT,
>    order_date TIMESTAMP(0),
>    customer_name STRING,
>    price DECIMAL(10, 5),
>    product_id INT,
>    order_status BOOLEAN,
>    PRIMARY KEY (order_id) NOT ENFORCED
>  ) WITH (
>    'connector' = 'mysql-cdc',
>    'hostname' = 'localhost',
>    'port' = '3306',
>    'username' = 'root',
>    'password' = '123456',
>    'database-name' = 'mydb',
>    'table-name' = 'orders'
>  );
[INFO] Execute statement succeed.

• postgres

Flink SQL> CREATE TABLE shipments (
>    shipment_id INT,
>    order_id INT,
>    origin STRING,
>    destination STRING,
>    is_arrived BOOLEAN,
>    PRIMARY KEY (shipment_id) NOT ENFORCED
>  ) WITH (
>    'connector' = 'postgres-cdc',
>    'hostname' = 'localhost',
>    'port' = '5432',
>    'username' = 'postgres',
>    'password' = 'postgres',
>    'database-name' = 'postgres',
>    'schema-name' = 'public',
>    'table-name' = 'shipments'
>  );
[INFO] Execute statement succeed.

• es

CREATE TABLE enriched_orders (
>    order_id INT,
>    order_date TIMESTAMP(0),
>    customer_name STRING,
>    price DECIMAL(10, 5),
>    product_id INT,
>    order_status BOOLEAN,
>    product_name STRING,
>    product_description STRING,
>    shipment_id INT,
>    origin STRING,
>    destination STRING,
>    is_arrived BOOLEAN,
>    PRIMARY KEY (order_id) NOT ENFORCED
>  ) WITH (
>      'connector' = 'elasticsearch-7',
>      'hosts' = 'http://localhost:9200',
>      'index' = 'enriched_orders'
>  );
[INFO] Execute statement succeed.

4.3 使用flink SQL将order、products、shipments关联，并将关联后的订单信息写入es

Flink SQL> INSERT INTO enriched_orders
>  SELECT o.*, p.name, p.description, s.shipment_id, s.origin, s.destination, s.is_arrived
>  FROM orders AS o
>  LEFT JOIN products AS p ON o.product_id = p.id
>  LEFT JOIN shipments AS s ON o.order_id = s.order_id;
[INFO] Submitting SQL update statement to the cluster...
[INFO] SQL update statement has been successfully submitted to the cluster:
Job ID: 6c670cd6c73be12d35a7796adb0ec8b4

flink web ui显示如下：

kibana中数据显示如下：

---

5.修改MySQL和postgres中的数据，测试es中的数据是否能实时更新

5.1在 MySQL 的 orders 表中插入一条数据

mysql> INSERT INTO orders-> VALUES (default, '2020-07-30 15:22:00', 'Jark', 29.71, 104, false);
Query OK, 1 row affected (0.01 sec)

5.2在 Postgres 的 shipment 表中插入一条数据

postgres=# INSERT INTO shipments
postgres-# VALUES (default,10004,'Shanghai','Beijing',false);
INSERT 0 1

5.3在 MySQL 的 orders 表中更新订单的状态

mysql> UPDATE orders SET order_status = true WHERE order_id = 10004;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1  Changed: 1  Warnings: 0

5.4在 Postgres 的 shipment 表中更新物流的状态

postgres=# UPDATE shipments SET is_arrived = true WHERE shipment_id = 1004;
UPDATE 1

5.5在 MYSQL 的 orders 表中删除一条数据

mysql> DELETE FROM orders WHERE order_id = 10004;
Query OK, 1 row affected (0.00 sec)

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