Conflict-free Replicated Data Types

This academic paper introduces Conflict-free Replicated Data Types (CRDTs), which are abstract data types designed for distributed systems where data is replicated across multiple locations. CRDTs allow any replica to be modified without needing immediate coordination with other replicas, ensuring high availability and low latency. The core concept is that CRDTs employ mathematically sound rules and specific concurrency semantics (like add-wins or last-writer-wins) to guarantee that replicas converge to the same state when they have received the same updates, even if updates occur concurrently. The paper explores various synchronization models for propagating updates between replicas, discusses key research findings related to preserving sequential semantics and handling concurrency, examines guarantees and limitations (including their relationship with the CAP theorem), highlights examples of applications where CRDTs are used, and outlines future research directions such as scalability and security. https://arxiv.org/pdf/1805.06358