| dbo:abstract
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- Commitment ordering (CO) is a class of interoperable serializability techniques in concurrency control of databases, transaction processing, and related applications. It allows optimistic (non-blocking) implementations. With the proliferation of multi-core processors, CO has also been increasingly utilized in concurrent programming, transactional memory, and software transactional memory (STM) to achieve serializability optimistically. CO is also the name of the resulting transaction schedule (history) property, defined in 1988 with the name dynamic atomicity. In a CO compliant schedule, the chronological order of commitment events of transactions is compatible with the precedence order of the respective transactions. CO is a broad special case of conflict serializability and effective means (reliable, high-performance, distributed, and scalable) to achieve global serializability (modular serializability) across any collection of database systems that possibly use different concurrency control mechanisms (CO also makes each system serializability compliant, if not already). Each not-CO-compliant database system is augmented with a CO component (the commitment order coordinator—COCO) which orders the commitment events for CO compliance, with neither data-access nor any other transaction operation interference. As such, CO provides a low overhead, general solution for global serializability (and distributed serializability), instrumental for global concurrency control (and distributed concurrency control) of multi-database systems and other , possibly highly distributed (e.g., within cloud computing, grid computing, and networks of smartphones). An (ACP; of any type) is a fundamental part of the solution, utilized to break global cycles in the conflict (precedence, serializability) graph. CO is the most general property (a necessary condition) that guarantees global serializability, if the database systems involved do not share concurrency control information beyond atomic commitment protocol (unmodified) messages and have no knowledge of whether transactions are global or local (the database systems are autonomous). Thus CO (with its variants) is the only general technique that does not require the typically costly distribution of local concurrency control information (e.g., local precedence relations, locks, timestamps, or tickets). It generalizes the popular strong strict two-phase locking (SS2PL) property, which in conjunction with the two-phase commit protocol (2PC), is the de facto standard to achieve global serializability across (SS2PL based) database systems. As a result, CO compliant database systems (with any different concurrency control types) can transparently join such SS2PL based solutions for global serializability. In addition, locking based global deadlocks are resolved automatically in a CO based multi-database environment, a vital side-benefit (including the special case of a completely SS2PL based environment; a previously unnoticed fact for SS2PL). Furthermore, strict commitment ordering (SCO; ), the intersection of Strictness and CO, provides better performance (shorter average transaction completion time and resulting in better transaction throughput) than SS2PL whenever read-write conflicts are present (identical blocking behavior for write-read and write-write conflicts; comparable locking overhead). The advantage of SCO is especially during lock contention. Strictness allows both SS2PL and SCO to use the same effective database recovery mechanisms. Two major generalizing variants of CO exist, extended CO (ECO; ) and multi-version CO (MVCO; ). They also provide global serializability without local concurrency control information distribution, can be combined with any relevant concurrency control, and allow optimistic (non-blocking) implementations. Both use additional information for relaxing CO constraints and achieving better concurrency and performance. Vote ordering (VO or Generalized CO (GCO); ) is a container schedule set (property) and technique for CO and all its variants. Local VO is necessary for guaranteeing global serializability if the atomic commitment protocol (ACP) participants do not share concurrency control information (have the generalized autonomy property). CO and its variants inter-operate transparently, guaranteeing global serializability and automatic global deadlock resolution together in a mixed, heterogeneous environment with different variants. (en)
- コミットメント順序付け（コミットメントじゅんじょづけ、英: Commitment Ordering or CO、コミット順序付け）は、データベース、トランザクション処理、関連する分散アプリケーションにおいて、互換性のある直列化可能性を実現する手法である。この手法を使うと、楽観的な(ブロックしない)実装が可能である。マルチコア・プロセッサの急増により、COは並列プログラミング、で利用され、特にソフトウェアトランザクショナルメモリにおいて楽観的に直列化可能性を達成するために用いられる。COはトランザクションのスケジュール(履歴)が持つ性質の名前としても用いられ、元は1988年に(dynamic atomicity)という名前で定義された。COに準拠したスケジュールでは、コミットメントイベントの時間順序が(英: precedence graph)のトランザクションの順序と一致する。 (ja)
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| rdfs:comment
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- コミットメント順序付け（コミットメントじゅんじょづけ、英: Commitment Ordering or CO、コミット順序付け）は、データベース、トランザクション処理、関連する分散アプリケーションにおいて、互換性のある直列化可能性を実現する手法である。この手法を使うと、楽観的な(ブロックしない)実装が可能である。マルチコア・プロセッサの急増により、COは並列プログラミング、で利用され、特にソフトウェアトランザクショナルメモリにおいて楽観的に直列化可能性を達成するために用いられる。COはトランザクションのスケジュール(履歴)が持つ性質の名前としても用いられ、元は1988年に(dynamic atomicity)という名前で定義された。COに準拠したスケジュールでは、コミットメントイベントの時間順序が(英: precedence graph)のトランザクションの順序と一致する。 (ja)
- Commitment ordering (CO) is a class of interoperable serializability techniques in concurrency control of databases, transaction processing, and related applications. It allows optimistic (non-blocking) implementations. With the proliferation of multi-core processors, CO has also been increasingly utilized in concurrent programming, transactional memory, and software transactional memory (STM) to achieve serializability optimistically. CO is also the name of the resulting transaction schedule (history) property, defined in 1988 with the name dynamic atomicity. In a CO compliant schedule, the chronological order of commitment events of transactions is compatible with the precedence order of the respective transactions. CO is a broad special case of conflict serializability and effective mea (en)
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