Locks with Constrained Sharing: A Proposal

本研究致力于提供对分布式数据库的高效事务访问的问题。提出了一种新的锁模式，称为有序共享模式，允许以受限的方式共享数据。通过使用三种锁模式：共享锁、有序共享锁和非共享锁，开发了一系列基于锁的并发控制协议。该系列中最严格的协议是用于数据库的两阶段锁定协议，而最允许的协议可以识别所有冲突保护的可序列化历史。这是第一个基于锁定的并发协议，可以识别整个类的冲突保护可序列化历史记录。在本项目期间，将对这些议定书进行理论和实证研究。理论上的比较是基于对协议产生的历史集合的分析。实证分析包括建立性能模型和数据库系统试验台。在分布式数据库试验台上开发并实现了基于有序共享锁的分布式数据库并发控制协议。最后，新的锁模式将用于开发用于数据库系统恢复、嵌套事务和抽象数据类型的协议。

This research address the problem of providing efficient transactional access to distributed databases. A new mode of locks, termed ordered-shared mode, is proposed that permits data sharing in a constrained manner. A family of locking-based concurrency control protocols is developed by using three modes of locks: shared, ordered-shared, and non-shared. The strictest protocol in this family is the two phase locking protocol for databases, while the most permissive recognizes all conflict- preserving serializable histories. This is the first locking- based concurrency protocol that recognizes the entire class of conflict-preserving serializable histories. Theoretical and empirical studies of these protocols will be conducted during this project. The theoretical comparison is based on the analysis of sets of histories produced by the protocols. The empirical analysis involves building a performance model and a database system test-bed. Distributed database concurrency control protocols based on ordered-shared locks will be developed and implemented on a distributed database test-bed. Finally, the new mode of locks will be used to develop protocols for database system recovery, nested transactions, and abstract data types.