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262 lines
8.9 KiB
Markdown
262 lines
8.9 KiB
Markdown
# Demo: PolarDB-X CDC to Elasticsearch
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This tutorial is to show how to quickly build streaming ETL for PolarDB-X with Flink CDC.
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Assuming we are running an e-commerce business. The product and order data stored in PolarDB-X.
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We want to enrich the orders using the product table, and then load the enriched orders to ElasticSearch in real time.
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In the following sections, we will describe how to use Flink PolarDB-X CDC to implement it.
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All exercises in this tutorial are performed in the Flink SQL CLI, and the entire process uses standard SQL syntax, without a single line of Java/Scala code or IDE installation.
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## Preparation
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Prepare a Linux or MacOS computer with Docker installed.
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### Starting components required
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The components required in this demo are all managed in containers, so we will use `docker-compose` to start them.
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Create `docker-compose.yml` file using following contents:
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```
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version: '2.1'
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services:
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polardbx:
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polardbx:
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image: polardbx/polardb-x:2.0.1
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container_name: polardbx
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ports:
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- "8527:8527"
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elasticsearch:
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image: 'elastic/elasticsearch:7.6.0'
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container_name: elasticsearch
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environment:
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- cluster.name=docker-cluster
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- bootstrap.memory_lock=true
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- ES_JAVA_OPTS=-Xms512m -Xmx512m
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- discovery.type=single-node
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ports:
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- '9200:9200'
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- '9300:9300'
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ulimits:
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memlock:
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soft: -1
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hard: -1
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nofile:
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soft: 65536
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hard: 65536
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kibana:
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image: 'elastic/kibana:7.6.0'
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container_name: kibana
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ports:
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- '5601:5601'
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volumes:
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- '/var/run/docker.sock:/var/run/docker.sock'
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```
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The Docker Compose environment consists of the following containers:
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- PolarDB-X: the `products`,`orders` tables will be store in the database. They will be joined enrich the orders.
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- Elasticsearch: mainly used as a data sink to store enriched orders.
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- Kibana: used to visualize the data in Elasticsearch.
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To start all containers, run the following command in the directory that contains the `docker-compose.yml` file.
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```shell
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docker-compose up -d
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```
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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.
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We can also visit [http://localhost:5601/](http://localhost:5601/) to see if Kibana is running normally.
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### Preparing Flink and JAR package required
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1. Download [Flink 1.16.0](https://archive.apache.org/dist/flink/flink-1.16.0/flink-1.16.0-bin-scala_2.12.tgz) and unzip it to the directory `flink-1.16.0`
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2. Download following JAR package required and put them under `flink-1.16.0/lib/`:
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**Download links are available only for stable releases, SNAPSHOT dependency need build by yourself. **
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- [flink-sql-connector-mysql-cdc-2.3.0.jar](https://repo1.maven.org/maven2/com/ververica/flink-sql-connector-mysql-cdc/2.3.0/flink-sql-connector-mysql-cdc-2.3.0.jar)
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- [flink-sql-connector-elasticsearch7-1.16.0.jar](https://repo.maven.apache.org/maven2/org/apache/flink/flink-sql-connector-elasticsearch7/1.16.0/flink-sql-connector-elasticsearch7-1.16.0.jar)
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### Preparing data in databases
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#### Preparing data in PolarDB-X
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1. Enter PolarDB-X Database:
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```shell
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mysql -h127.0.0.1 -P8527 -upolardbx_root -p"123456"
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```
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2. Create tables and populate data:
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```sql
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-- PolarDB-X
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CREATE TABLE products (
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id INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY,
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name VARCHAR(255) NOT NULL,
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description VARCHAR(512)
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) AUTO_INCREMENT = 101;
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INSERT INTO products
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VALUES (default,"scooter","Small 2-wheel scooter"),
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(default,"car battery","12V car battery"),
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(default,"12-pack drill bits","12-pack of drill bits with sizes ranging from #40 to #3"),
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(default,"hammer","12oz carpenter's hammer"),
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(default,"hammer","14oz carpenter's hammer"),
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(default,"hammer","16oz carpenter's hammer"),
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(default,"rocks","box of assorted rocks"),
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(default,"jacket","water resistent black wind breaker"),
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(default,"spare tire","24 inch spare tire");
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CREATE TABLE orders (
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order_id INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY,
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order_date DATETIME NOT NULL,
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customer_name VARCHAR(255) NOT NULL,
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price DECIMAL(10, 5) NOT NULL,
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product_id INTEGER NOT NULL,
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order_status BOOLEAN NOT NULL -- Whether order has been placed
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) AUTO_INCREMENT = 10001;
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INSERT INTO orders
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VALUES (default, '2020-07-30 10:08:22', 'Jark', 50.50, 102, false),
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(default, '2020-07-30 10:11:09', 'Sally', 15.00, 105, false),
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(default, '2020-07-30 12:00:30', 'Edward', 25.25, 106, false);
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```
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## Starting Flink cluster and Flink SQL CLI
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1. Use the following command to change to the Flink directory:
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```
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cd flink-1.16.0
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```
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2. Use the following command to start a Flink cluster:
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```shell
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./bin/start-cluster.sh
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```
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Then we can visit [http://localhost:8081/](http://localhost:8081/) to see if Flink is running normally, and the web page looks like:
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3. Use the following command to start a Flink SQL CLI:
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```shell
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./bin/sql-client.sh
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```
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We should see the welcome screen of the CLI client.
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## Creating tables using Flink DDL in Flink SQL CLI
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First, enable checkpoints every 3 seconds
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```sql
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-- Flink SQL
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Flink SQL> SET execution.checkpointing.interval = 3s;
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```
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Then, create tables that capture the change data from the corresponding database tables.
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```sql
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-- Flink SQL
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Flink SQL> SET execution.checkpointing.interval = 3s;
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-- create source table2 - orders
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Flink SQL> CREATE TABLE orders (
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order_id INT,
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order_date TIMESTAMP(0),
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customer_name STRING,
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price DECIMAL(10, 5),
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product_id INT,
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order_status BOOLEAN,
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PRIMARY KEY (order_id) NOT ENFORCED
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) WITH (
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'connector' = 'mysql-cdc',
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'hostname' = '127.0.0.1',
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'port' = '8527',
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'username' = 'polardbx_root',
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'password' = '123456',
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'database-name' = 'mydb',
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'table-name' = 'orders'
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);
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-- create source table2 - products
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CREATE TABLE products (
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id INT,
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name STRING,
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description STRING,
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PRIMARY KEY (id) NOT ENFORCED
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) WITH (
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'connector' = 'mysql-cdc',
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'hostname' = '127.0.0.1',
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'port' = '8527',
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'username' = 'polardbx_root',
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'password' = '123456',
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'database-name' = 'mydb',
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'table-name' = 'products'
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);
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```
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Finally, create `enriched_orders` table that is used to load data to the Elasticsearch.
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```sql
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-- Flink SQL
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-- create sink table - enrich_orders
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Flink SQL> CREATE TABLE enriched_orders (
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order_id INT,
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order_date TIMESTAMP(0),
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customer_name STRING,
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price DECIMAL(10, 5),
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product_id INT,
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order_status BOOLEAN,
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product_name STRING,
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product_description STRING,
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PRIMARY KEY (order_id) NOT ENFORCED
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) WITH (
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'connector' = 'elasticsearch-7',
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'hosts' = 'http://localhost:9200',
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'index' = 'enriched_orders'
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);
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```
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## Enriching orders and load to ElasticSearch
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Use Flink SQL to join the `order` table with the `products` table to enrich orders and write to the Elasticsearch.
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```sql
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-- Flink SQL
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Flink SQL> INSERT INTO enriched_orders
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SELECT o.order_id,
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o.order_date,
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o.customer_name,
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o.price,
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o.product_id,
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o.order_status,
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p.name,
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p.description
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FROM orders AS o
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LEFT JOIN products AS p ON o.product_id = p.id;
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```
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Now, the enriched orders should be shown in Kibana.
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Visit [http://localhost:5601/app/kibana#/management/kibana/index_pattern](http://localhost:5601/app/kibana#/management/kibana/index_pattern) to create an index pattern `enriched_orders`.
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Visit [http://localhost:5601/app/kibana#/discover](http://localhost:5601/app/kibana#/discover) to find the enriched orders.
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Next, do some change in the databases, and then the enriched orders shown in Kibana will be updated after each step in real time.
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1. Insert a new order in PolarDB-X
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```sql
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--PolarDB-X
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INSERT INTO orders
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VALUES (default, '2020-07-30 15:22:00', 'Jark', 29.71, 104, false);
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```
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2. Update the order status in PolarDB-X
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```sql
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--PolarDB-X
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UPDATE orders SET order_status = true WHERE order_id = 10004;
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```
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3. Delete the order in PolarDB-X
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```sql
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--PolarDB-X
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DELETE FROM orders WHERE order_id = 10004;
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```
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The changes of enriched orders in Kibana are as follows:
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## Clean up
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After finishing the tutorial, run the following command to stop all containers in the directory of `docker-compose.yml`:
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```shell
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docker-compose down
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```
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Run the following command to stop the Flink cluster in the directory of Flink `flink-1.16.0`:
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```shell
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./bin/stop-cluster.sh
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```
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