This documentation is for an unreleased version of Apache Flink CDC. We recommend you use the latest stable version.

Demo: SqlServer CDC to Elasticsearch #

Create docker-compose.yml file using following contents:

version: '2.1'
services:
   sqlserver:
     image: mcr.microsoft.com/mssql/server:2019-latest
     container_name: sqlserver
     ports:
       - "1433:1433"
     environment:
       - "MSSQL_AGENT_ENABLED=true"
       - "MSSQL_PID=Standard"
       - "ACCEPT_EULA=Y"
       - "SA_PASSWORD=Password!"
   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

The Docker Compose environment consists of the following containers:

SqlServer: SqlServer database.
Elasticsearch: store the join result of the orders and products table.
Kibana: mainly used to visualize the data in Elasticsearch.

To start all containers, run the following command in the directory that contains the docker-compose.yml file:

docker-compose up -d

This command automatically starts all the containers defined in the Docker Compose configuration in a detached mode. Run docker ps to check whether these containers are running properly. You can also visit http://localhost:5601/ to see if Kibana is running normally.

Don’t forget to run the following command to stop and remove all containers after you finished the tutorial:

docker-compose down

Download following JAR package to <FLINK_HOME>/lib:

Download links are available only for stable releases, SNAPSHOT dependencies need to be built based on master or release branches by yourself.

Preparing data in SqlServer database

Create databases/tables and populate data

-- Sqlserver
CREATE DATABASE inventory;
GO
USE inventory;
EXEC sys.sp_cdc_enable_db;

-- Create and populate our products using a single insert with many rows
CREATE TABLE products (
id INTEGER IDENTITY(101,1) NOT NULL PRIMARY KEY,
name VARCHAR(255) NOT NULL,
description VARCHAR(512),
weight FLOAT
);
INSERT INTO products(name,description,weight)
VALUES ('scooter','Small 2-wheel scooter',3.14);
INSERT INTO products(name,description,weight)
VALUES ('car battery','12V car battery',8.1);
INSERT INTO products(name,description,weight)
VALUES ('12-pack drill bits','12-pack of drill bits with sizes ranging from #40 to #3',0.8);
INSERT INTO products(name,description,weight)
VALUES ('hammer','12oz carpenter''s hammer',0.75);
INSERT INTO products(name,description,weight)
VALUES ('hammer','14oz carpenter''s hammer',0.875);
INSERT INTO products(name,description,weight)
VALUES ('hammer','16oz carpenter''s hammer',1.0);
INSERT INTO products(name,description,weight)
VALUES ('rocks','box of assorted rocks',5.3);
INSERT INTO products(name,description,weight)
VALUES ('jacket','water resistent black wind breaker',0.1);
INSERT INTO products(name,description,weight)
VALUES ('spare tire','24 inch spare tire',22.2);
EXEC sys.sp_cdc_enable_table @source_schema = 'dbo', @source_name = 'products', @role_name = NULL, @supports_net_changes = 0;
-- Create some very simple orders
CREATE TABLE orders (
id INTEGER IDENTITY(10001,1) NOT NULL PRIMARY KEY,
order_date DATE NOT NULL,
purchaser INTEGER NOT NULL,
quantity INTEGER NOT NULL,
product_id INTEGER NOT NULL,
FOREIGN KEY (product_id) REFERENCES products(id)
);
INSERT INTO orders(order_date,purchaser,quantity,product_id)
VALUES ('16-JAN-2016', 1001, 1, 102);
INSERT INTO orders(order_date,purchaser,quantity,product_id)
VALUES ('17-JAN-2016', 1002, 2, 105);
INSERT INTO orders(order_date,purchaser,quantity,product_id)
VALUES ('19-FEB-2016', 1002, 2, 106);
INSERT INTO orders(order_date,purchaser,quantity,product_id)
VALUES ('21-FEB-2016', 1003, 1, 107);
EXEC sys.sp_cdc_enable_table @source_schema = 'dbo', @source_name = 'orders', @role_name = NULL, @supports_net_changes = 0;
GO

Launch a Flink cluster and start a Flink SQL CLI:

-- Flink SQL
-- checkpoint every 3000 milliseconds                       
Flink SQL> SET execution.checkpointing.interval = 3s;

Flink SQL> CREATE TABLE products (
    id INT,
    name STRING,
    description STRING,
    PRIMARY KEY (id) NOT ENFORCED
  ) WITH (
    'connector' = 'sqlserver-cdc',
    'hostname' = 'localhost',
    'port' = '1433',
    'username' = 'sa',
    'password' = 'Password!',
    'database-name' = 'inventory',
    'table-name' = 'dbo.products'
  );

Flink SQL> CREATE TABLE orders (
   id INT,
   order_date DATE,
   purchaser INT,
   quantity INT,
   product_id INT,
   PRIMARY KEY (id) NOT ENFORCED
 ) WITH (
    'connector' = 'sqlserver-cdc',
    'hostname' = 'localhost',
    'port' = '1433',
    'username' = 'sa',
    'password' = 'Password!',
    'database-name' = 'inventory',
    'table-name' = 'dbo.orders'
);

Flink SQL> CREATE TABLE enriched_orders (
   order_id INT,
   order_date DATE,
   purchaser INT,
   quantity INT,
   product_name STRING,
   product_description STRING,
   PRIMARY KEY (order_id) NOT ENFORCED
 ) WITH (
     'connector' = 'elasticsearch-7',
     'hosts' = 'http://localhost:9200',
     'index' = 'enriched_orders_1'
 );

Flink SQL> INSERT INTO enriched_orders
  SELECT o.id,o.order_date,o.purchaser,o.quantity, p.name, p.description
  FROM orders AS o
  LEFT JOIN products AS p ON o.product_id = p.id;

Check result in Elasticsearch

Check the data has been written to Elasticsearch successfully, you can visit Kibana to see the data.

Make changes in SqlServer and watch result in Elasticsearch

Do some changes in the databases, and then the enriched orders shown in Kibana will be updated after each step in real time.

INSERT INTO orders(order_date,purchaser,quantity,product_id) VALUES ('22-FEB-2016', 1006, 22, 107);
GO

UPDATE orders SET quantity = 11 WHERE id = 10001;
GO

DELETE FROM orders WHERE id = 10004;
GO