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In distributed computing, a conflict-free replicated data type (abbreviated CRDT) is a type of specially-designed data structure used to achieve strong eventual consistency (SEC) and monotonicity (absence of rollbacks).〔 〕 There are two alternative routes to ensuring SEC: operation-based CRDTs〔 〕 and state-based CRDTs.〔 〕 The two alternatives are equivalent, as one can emulate the other,〔 but operation-based CRDTs require additional guarantees from the communication middleware.〔 CRDTs are used to replicate data across multiple computers in a network, executing updates without the need for remote synchronization. This would lead to merge conflicts in systems using conventional eventual consistency technology, but CRDTs are designed such that conflicts are mathematically impossible.〔 〕 Under the constraints of the CAP theorem they provide the strongest consistency guarantees for available/partition-tolerant (AP) settings. In contrast, consensus protocols such as Paxos are required for strongly-consistent/partition-tolerant (CP) settings. The CRDT concept was first formally defined in 2007 by Marc Shapiro and Nuno Preguiça in terms of operation commutativity,〔 〕 and development was initially motivated by collaborative text editing.〔 〕〔 〕 The concept of semilattice evolution of replicated states was first defined by Baquero and Moura in 1997,〔〔 〕 and development was initially motivated by mobile computing. The two concepts were later unified in 2011.〔〔 ==Overview== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Conflict-free replicated data type」の詳細全文を読む スポンサード リンク
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