Living Reference Work Entry

Encyclopedia of Database Systems

pp 1-5

Date: Latest Version

Replicated Data Types

  • Marc ShapiroAffiliated withSorbonne-Universités-UPMC-LIP6 & Inria Email author 


Commutative replicated data types (CmRDTs); Conflict-free replicated data types (CRDTs); Convergent replicated data types (CvRDTs); Replicated abstract data types (RADTs); Replicated data types (RDTs)


Conflict-free replicated data types (CRDTs) were invented to encapsulate and hide the complexity of managing Eventual Consistency. A CRDT is an abstract data type that implements some familiar object, such as a counter, a set, or a sequence. Internally, a CRDT is replicated, to provide reliability, availability, and responsiveness. Encapsulation hides the details of replication and conflict resolution.

In a sequential execution, the CRDT behaves like its sequential counterpart. Thus, a CRDT is reusable by programmers without detailed knowledge of its implementation. Furthermore, a CRDT supports concurrent updates and encapsulates some strategy that provably ensures that replicas of the CRDT will converge despite this concurrency. Concurrent updates are never conflicting.

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