CRDTs

Kind: mechanism

Layer: Causality Core

Aliases: Conflict-Free Replicated Data Types

Record: architecture:crdts

Severity: contextual

Scope: distributed state, replication, convergence

Canonical: Ontology

A mechanism that stores replicated state in data types whose merge is commutative, so replicas converge without coordination.

Listed in Architecture principles, after Hybrid Logical Clocks and before Total-Order Broadcast.

Requires

• Commutative Merge

Reinforces

• Eventual Consistency
• Causal Consistency

Enables

• Conflict-Free Replica Convergence

In tension with

• Metadata Overhead
• Last-Write-Wins Overwrite

Tensions

• CRDTs / Metadata Overhead
• CRDTs / Last-Write-Wins Overwrite

Violated by

• Lost Update

Severity

• contextual

Category

• Causality / Ordering / Distributed Time

Linked from

• Causality / Ordering / Distributed Time
• Event / Messaging / Asynchronous Architecture
• Causality / Ordering / Distributed Time
• Severity levels
• The resolutions