cqrs

CQRS separates state-changing commands from read-only queries to optimize performance. By isolating command handlers from read models, it enables independent scaling of write and read workloads in complex domains.

You should use CQRS when read and write workloads diverge significantly. It applies when you need denormalized read models for reporting, allowing you to scale reads and writes independently to improve overall performance.

To implement a basic CQRS split, introduce separate command handlers for state changes and a read model projection for queries. Validate commands explicitly, then verify improved read throughput against your updated projections.

CQRS introduces eventual consistency and increased coordination complexity. Because read models are updated from domain events, projections lag behind commands, requiring you to document clear trade-offs and projection strategies for your architecture.

Using domain-driven design with CQRS allows read models and projections to be updated from domain events, supporting fast denormalized queries. This makes reporting easier and optimizes read throughput without impacting write performance.

CQRS limitations include eventual consistency and increased coordination complexity. You should not use CQRS if your domain is simple or if read and write workloads are similar, as the architectural overhead outweighs the performance benefits.