CQRS Design

Implement Command Query Responsibility Segregation (CQRS) to align data models with actual usage patterns and enable independent scaling of reads and writes.

Context

You are designing or refactoring a system with complex read and write patterns. The user faces performance issues, audit requirements, or divergent read/write needs. Read their current data access patterns.

Domain Context

Based on Greg Young's CQRS work and Fowler's research:

• Command Side: Optimized for writes; enforces business rules; maintains single source of truth
• Query Side: Optimized for reads; denormalized for performance; eventual consistency acceptable
• Event Sourcing: Often paired with CQRS; commands generate events, events drive queries
• Read Models: Projections built from events; can be recreated from command side state
• Consistency Boundary: Commands are strongly consistent within aggregate; queries lag slightly

Instructions