CRDTtyyppejä

CRDTtyyppejä, a Finnish term, translates to "CRDT types" in English. CRDT stands for Conflict-free Replicated Data Type. These are data structures designed for distributed systems where multiple replicas can be updated concurrently and independently without requiring coordination or a central authority to resolve conflicts. The inherent design of CRDTs ensures that replicas will eventually converge to the same state, even in the presence of network partitions or high latency.

There are broadly two main categories of CRDTs: state-based CRDTs and operation-based CRDTs. State-based CRDTs, also known as CvRDTs (Convergent Replicated Data Types), exchange entire states or summaries of states between replicas. The merge operation in CvRDTs is commutative, associative, and idempotent, guaranteeing convergence. Operation-based CRDTs, or CmRDTs (Commutative Replicated Data Types), transmit update operations. For CmRDTs to converge, operations must be delivered to all replicas and be commutative, or a mechanism for causal delivery must be in place.

Common examples of CRDTs include grow-only counters, PN-counters (positive-negative counters), grow-only sets, LWW-registers (last-writer-wins registers), G-trees (grow-only trees), and various list implementations like the rope CRDT or sequencer CRDT. These data structures are crucial for applications requiring high availability and low latency, such as collaborative editing tools, distributed databases, and multiplayer online games. The choice of CRDT type depends on the specific application requirements and the nature of the data being managed.