A simpler and more flexible approach to consistency in event-driven systems
What is it?

Dynamic Consistency Boundaries (DCB) is a technique for enforcing consistency in event-driven systems without relying on rigid transactional boundaries.

Traditional systems use strict constraints to maintain immediate consistency, while event-driven architectures embrace eventual consistency for scalability and resilience. However, this flexibility raises challenges in defining where and how consistency should be enforced.

Introduced by Sara Pellegrini in her blog post "Killing the Aggregate", DCB provides a pragmatic approach to balancing strong consistency with flexibility. DCB allows for the selective enforcement of strong consistency where needed, particularly for operations that span multiple entities. This ensures critical business processes and cross-entity invariants remain reliable while avoiding the constraints of traditional transactional models. DCB helps teams optimize performance, scalability, and operational correctness by defining context-sensitive consistency boundaries.