Eventual Consistency

Eventual consistency is an important correctness criterion in systems with a lazy, updateanywhere 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 referred to as geo-replication, and mobile computing environments, eventual consistency is popular, as it allows individual replicas to serve client requests and provide a response before coordinating with other replicas. Conflict-free replicated data types (CRDTs) were invented to encapsulate and hide the complexity of managing eventual consistency.