Change data capture (CDC) with Apache Beam and Java

25 Sep 2023

apacheflink

Introduction

Change Data Capture (CDC) is a technique used to track and capture changes made to data in a database. It enables real-time data integration and replication, allowing applications to react to data changes as soon as they occur. In this blog post, we will explore how to implement CDC using Apache Beam and Java, providing a step-by-step guide to set up a CDC pipeline.

Prerequisites

To follow along with this tutorial, ensure that you have the following software installed:

Java Development Kit (JDK) 8+
Apache Maven
Apache Beam

Setting up the CDC Pipeline

Step 1: Set up a Maven project

Create a new Maven project using the following command:

mvn archetype:generate -DgroupId=com.example -DartifactId=my-cdc-project -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false

Step 2: Add dependencies

Navigate to the project directory and open the pom.xml file. Add the following dependencies:

<dependencies>
    <dependency>
        <groupId>org.apache.beam</groupId>
        <artifactId>beam-sdks-java-core</artifactId>
        <version>2.33.0</version>
    </dependency>
    <dependency>
        <groupId>org.apache.beam</groupId>
        <artifactId>beam-sdks-java-io-jdbc</artifactId>
        <version>2.33.0</version>
    </dependency>
</dependencies>

Step 3: Implement the CDC pipeline

Create a new Java class, CDCPipeline, and implement the pipeline logic. Here’s an example implementation:

import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.io.jdbc.JdbcIO;
import org.apache.beam.sdk.options.PipelineOptions;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.sdk.values.Row;

public class CDCPipeline {
    public static void main(String[] args) {
        PipelineOptions options = PipelineOptionsFactory.fromArgs(args).create();

        Pipeline pipeline = Pipeline.create(options);

        pipeline
            .apply("Read from Database", JdbcIO.<Row>read()
                .withDataSourceConfiguration(JdbcIO.DataSourceConfiguration.create(
                    "org.postgresql.Driver", "jdbc:postgresql://localhost:5432/mydatabase")
                    .withUsername("username")
                    .withPassword("password"))
                .withQuery("SELECT * FROM mytable")
                .withRowMapper(new MyRowMapper()))
            .apply("Process Changes", ProcessChangesTransform());

        pipeline.run().waitUntilFinish();
    }
}

class MyRowMapper implements JdbcIO.RowMapper<Row> {
    @Override
    public Row mapRow(ResultSet resultSet) throws Exception {
        // Map result set to Row object
    }
}

class ProcessChangesTransform extends PTransform<PCollection<Row>, PCollection<ProcessedRow>> {
    @Override
    public PCollection<ProcessedRow> expand(PCollection<Row> input) {
        // Process the changes and return a new PCollection of ProcessedRow objects
    }
}

class ProcessedRow {
    // Define the structure of the processed row
}

Step 4: Run the CDC pipeline

Compile and run the CDC pipeline using the following command:

mvn compile exec:java -Dexec.mainClass=com.example.CDCPipeline -Pdirect-runner

Conclusion

Apache Beam provides a powerful framework for implementing Change Data Capture pipelines using Java. By following the steps outlined in this tutorial, you can set up a CDC pipeline to capture and process data changes in real-time. Start exploring the potential of CDC with Apache Beam today!

#cdc #apacheflink