Efficient State-Based CRDTs by Delta-Mutation

  • Paulo Sérgio Almeida
  • Ali ShokerEmail author
  • Carlos Baquero
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 9466)


CRDTs are distributed data types that make eventual consistency of a distributed object possible and non ad-hoc. Specifically, state-based CRDTs ensure convergence through disseminating the entire state, that may be large, and merging it to other replicas; whereas operation-based CRDTs disseminate operations (i.e., small states) assuming an exactly-once reliable dissemination layer. We introduce Delta State Conflict-Free Replicated Datatypes (\(\delta \)-CRDT) that can achieve the best of both worlds: small messages with an incremental nature, disseminated over unreliable communication channels. This is achieved by defining \(\delta \) -mutators to return a delta-state, typically with a much smaller size than the full state, that is joined to both: local and remote states. We introduce the \(\delta \)-CRDT framework, and we explain it through establishing a correspondence to current state-based CRDTs. In addition, we present an anti-entropy algorithm that ensures causal consistency, and two \(\delta \)-CRDT specifications of well-known replicated datatypes.


Replicated data types State-based CRDT Delta mutation 


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Copyright information

© Springer International Publishing Switzerland 2015

Authors and Affiliations

  • Paulo Sérgio Almeida
    • 1
  • Ali Shoker
    • 1
    Email author
  • Carlos Baquero
    • 1
  1. 1.HASLab/INESC TEC and Universidade Do MinhoBragaPortugal

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