cqrs-pattern

You need CQRS and event sourcing for backend architecture when a bounded context requires independent scaling of reads and writes or complex projection logic. It separates write-side domain logic from read-side query models to prevent domain pollution.

To implement a transactional outbox pattern in Go, use standardized command handler patterns to isolate domain-layer mutations, then dispatch events via idempotent projector designs. This ensures reliable event-driven consistency without polluting the domain model.

Choose between a simple read model or full event-sourced CQRS based on your business needs. A decision framework evaluates architectural requirements to determine if you need basic independent scaling or advanced event-driven consistency.

To isolate complex domain logic from query-side performance, implement Command Query Responsibility Segregation. This separates state-mutating command handlers from read-side query models, allowing each side to scale and perform independently.

A limitation of using CQRS for domain-driven design is managing eventual consistency between write-side commands and read-side projections. It is best suited for core bounded contexts rather than simple CRUD services.