Encyclopedia of Database Systems

Living Edition
| Editors: Ling Liu, M. Tamer Özsu

Eventual Consistency

  • Marc ShapiroEmail author
  • Bettina Kemme
Living reference work entry

Later version available View entry history

DOI: https://doi.org/10.1007/978-1-4899-7993-3_1366-2



In a replicated database, the consistency level defines whether and how the values of the replicas of a logical object may diverge in the presence of updates. Eventual consistency is the weakest consistency level that guarantees convergence. Informally, it requires that all replicas of an object will eventually reach the same final value, assuming that no new updates are submitted to the object.

Formal Definition and Usage

Eventual consistency is an important correctness criteria in systems with a lazy, update-anywhere strategy, also referred to as optimistic replication. Update operations can be submitted and executed on any node, and the propagation of updates occurs lazily after they are committed. Conflict resolution and reconciliation must ensure that all replicas (copies) of a logical object eventually converge to the same value. Different objects are considered independent. Especially in wide-area settings, also...


Conflict Resolution Eventual Consistency Consistency Level Client Request Logical Object 
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Recommended Reading

  1. 1.
    Saito Y, Shapiro M. Optimistic replication. ACM Comput Surv. 2005;37(1):42–81.CrossRefzbMATHGoogle Scholar
  2. 2.
    Vogels W. Eventually consistent. ACM Queue. 2008;6(6):14–19.CrossRefGoogle Scholar
  3. 3.
    Terry D. Replicated data consistency explained through baseball. Commun ACM. 2013;56(12):82–89.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media LLC 2017

Authors and Affiliations

  1. 1.UPMC-LIP6 & INRIA ParisParisFrance
  2. 2.School of Computer Science, McGill UniversityMontrealCanada

Section editors and affiliations

  • Bettina Kemme
    • 1
  1. 1.School of Computer ScienceMcGill UniversityMontrealCanada