使用Elasticsearch订阅PolarDB-X CDC

本小节介绍如何通过PolarDB-X借助Flink-CDC将数据导入至Elasticsearch。

准备组件

我们假设您运行在一台MacOS或者Linux机器上，并且已经安装Docker。

配置容器

配置docker-compose.yml。

version: '2.1'
services:
  polardbx:
    polardbx:
    image: polardbx/polardb-x:2.0.1
    container_name: polardbx
    ports:
      - "8527:8527"
  elasticsearch:
    image: 'elastic/elasticsearch:7.6.0'
    container_name: elasticsearch
    environment:
      - cluster.name=docker-cluster
      - bootstrap.memory_lock=true
      - ES_JAVA_OPTS=-Xms512m -Xmx512m
      - discovery.type=single-node
    ports:
      - '9200:9200'
      - '9300:9300'
    ulimits:
      memlock:
        soft: -1
        hard: -1
      nofile:
        soft: 65536
        hard: 65536
  kibana:
    image: 'elastic/kibana:7.6.0'
    container_name: kibana
    ports:
      - '5601:5601'
    volumes:
      - '/var/run/docker.sock:/var/run/docker.sock'

该Docker Compose中包含的容器有：

PolarDB-X：商品表products和订单表orders将存储在该数据库中，这两张表将进行关联，得到一张包含更多信息的订单表enriched_orders。
Elasticsearch：最终的订单表enriched_orders将写到Elasticsearch。
Kibana：用来可视化ElasticSearch的数据。

启动容器

在 docker-compose.yml所在目录下，执行下面的命令来启动所需的组件：

docker-compose up -d

该命令将以detached模式自动启动Docker Compose配置中定义的所有容器。您可以通过docker ps命令来观察上述的容器是否正常启动，也可以通过访问http://localhost:5601/来查看Kibana是否正常运行。

准备数据

使用已创建的用户名和密码登录PolarDB-X。

mysql -h127.0.0.1 -P8527 -upolardbx_root -p"123456"

CREATE DATABASE mydb;
USE mydb;

-- 创建一张产品表，并写入一些数据
CREATE TABLE products (
                          id INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY,
                          name VARCHAR(255) NOT NULL,
                          description VARCHAR(512)
) AUTO_INCREMENT = 101;

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");


-- 创建一张订单表，并写入一些数据
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;

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);

下载Flink和所需的依赖包

下载Flink 1.13.2并将其解压至目录flink-1.13.2。
下载下列依赖包，并将它们放到目录flink-1.13.2/lib/下。

说明：下载链接只对已发布的版本有效，SNAPSHOT版本需要本地编译。

用于订阅PolarDB-X Binlog：flink-sql-connector-mysql-cdc-2.3-SNAPSHOT.jar
用于写入Elasticsearch：flink-sql-connector-elasticsearch7_2.11-1.13.2.jar
启动Flink服务：
```
./bin/start-cluster.sh
```

访问http://localhost:8081/，查看Flink是否正常运行：

Flink UI

启动Flink SQL CLI：shell ./bin/sql-client.sh

在Flink SQL CLI中使用Flink DDL创建表

-- 设置间隔时间为3秒                       
Flink SQL> SET execution.checkpointing.interval = 3s;

-- 创建source1（订单表）
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' = '127.0.0.1',
    'port' = '8527',
    'username' = 'polardbx_root',
    'password' = '123456',
    'database-name' = 'mydb',
    'table-name' = 'orders'
 );

-- 创建source2（产品表）
CREATE TABLE products (
    id INT,
    name STRING,
    description STRING,
    PRIMARY KEY (id) NOT ENFORCED
  ) WITH (
    'connector' = 'mysql-cdc',
    'hostname' = '127.0.0.1',
    'port' = '8527',
    'username' = 'polardbx_root',
    'password' = '123456',
    'database-name' = 'mydb',
    'table-name' = 'products'
);

-- 创建sink（关联后的结果表）
Flink SQL> 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,
   PRIMARY KEY (order_id) NOT ENFORCED
 ) WITH (
     'connector' = 'elasticsearch-7',
     'hosts' = 'http://localhost:9200',
     'index' = 'enriched_orders'
 );

-- 执行读取和写入   
Flink SQL> INSERT INTO enriched_orders
  SELECT o.order_id,
    o.order_date,
    o.customer_name,
    o.price,
    o.product_id,
    o.order_status,
    p.name,
    p.description
 FROM orders AS o
 LEFT JOIN products AS p ON o.product_id = p.id;

在Kibana中查看数据

访问http://localhost:5601/app/kibana#/management/kibana/index_pattern，创建index pattern enriched_orders，之后可以在http://localhost:5601/app/kibana#/discover看到写入的数据。

修改监听表数据并查看增量数据变动

在PolarDB-X中依次执行如下修改操作，每执行一步就刷新一次Kibana，可以看到Kibana中显示的订单数据将实时更新。

INSERT INTO orders VALUES (default, '2020-07-30 15:22:00', 'Jark', 29.71, 104, false);

UPDATE orders SET order_status = true WHERE order_id = 10004;

DELETE FROM orders WHERE order_id = 10004;

清理环境

在docker-compose.yml文件所在的目录下，执行如下命令停止所有容器：

docker-compose down

进入Flink的部署目录，停止Flink集群：

./bin/stop-cluster.sh