Change Data Capture (CDC) is a technique used to track row-level changes in database tables in response to create, update and delete operations. Different databases use different techniques to expose these change data events - for example, logical decoding in PostgreSQL, MySQL binary log (binlog) etc. This is a powerful capability, but useful only if there is a way to tap into these event logs and make it available to other services which depend on that information.

Debezium does just that! It is a distributed platform that builds on top of Change Data Capture features available in different databases. It provides a set of Kafka Connect connectors which tap into row-level changes (using CDC) in database table(s) and convert them into event streams. These event streams are sent to Apache Kafka which is a scalable event streaming platform - a perfect fit! Once the change log events are in Kafka, they will be available to all the downstream applications.

The diagram (from the debezium.io website) summarises it nicely!

This blog is a guide to getting started with setting up a change data capture based system on Azure using Debezium, Azure DB for PostgreSQL and Azure Event Hubs (for Kafka). It will use the Debezium PostgreSQL connector to stream database modifications from PostgreSQL to Kafka topics in Azure Event Hubs

Although I have used managed Azure services for demonstration purposes these instructions should work for any other setup as well e.g. a local Kafka cluster and PostgreSQL instance.

#databases #postrgesql #kafka #developer