Example of CQRS Design Pattern

Let’s understand CQRS Design Pattern through the example of E-commerce Website.

In our Ordering E-commerce microservices architecture, we’re introducing a new approach to database design using the CQRS pattern. We’ve decided to split our databases into two separate parts to better manage our data and improve performance.

• Firstly, we’ll have a write database that focuses on handling all write operations, such as creating and updating orders. This database will be optimized for transactional consistency and relational data modeling, making it suitable for managing the core data changes.
• Secondly, we’ll introduce a read database dedicated to handling read operations, such as querying for order details and order history. This database will be designed for high performance and scalability, using a NoSQL database like MongoDB or Cassandra.

Synchronization

To keep these two databases in sync, we’ll implement a messaging system using Apache Kafka. Kafka’s publish/subscribe model will allow us to propagate changes from the write database to the read database in real-time, ensuring that the data remains consistent across both databases.

Tech-Stack

For the tech stack, we’re considering using MySQL or PostgreSQL for the write database due to their strong support for ACID transactions and relational data modeling. For the read database, we’re leaning towards using MongoDB or Cassandra for their scalability and ability to handle large volumes of data efficiently.

By adopting the CQRS pattern and splitting our databases in this way, we believe we can improve the performance and scalability of our Ordering microservices, providing a better experience for our users.

The Command Query Responsibility Segregation (CQRS) design pattern has emerged as a powerful architectural pattern for building complex and scalable software systems. By separating the responsibilities of reading and writing data, CQRS allows for more flexible and efficient designs, particularly in domains with high-performance and scalability requirements. In this article, we will explore the key concepts of CQRS, its benefits and challenges, and how it can be implemented in real-world applications.