CQRS

CQRS stands for Command Query Responsibility Segregation. It's an architectural pattern that separates the read and write operations for a data store.

How it works:

• Commands: These are instructions to modify the system's state. They are typically asynchronous and idempotent.
• Queries: These are used to retrieve information from the system without modifying its state. They are typically read-only operations.

Benefits of CQRS:

• Improved performance: By separating read and write operations, you can optimize each independently.
• Increased scalability: You can scale read and write components differently based on their load.
• Enhanced security: Isolating write operations can help protect sensitive data.
• Better testability: Separating concerns makes unit testing easier.

Example

Monolith System with multi storage

• Write model: A transactional database (e.g., SQL Server) for handling commands like placing orders, updating product inventory.
• Read model: A read-optimized database (e.g., NoSQL like MongoDB) for handling queries like product catalog, order history.

Microservices System CQRS is a natural fit for microservices architectures. It aligns perfectly with the principles of independent services, each responsible for a specific domain.

• Write model:
  • Order Service: Handles placing orders, canceling orders, updating order status.
  • Inventory Service: Handles updating product inventory levels.
• Read model:
  • Customer Service: Uses events from Order and Inventory services to update its read model.

Architecture

With event sourcing

On aws

Logical