Understanding Degrees of Isolation

了解隔离度

• 批准号: 9802066
• 负责人: Barbara Liskov
• 金额: $ 25.5万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9802066&HistoricalAwards=false
• 关键词: Understanding; Degrees; Isolation

This research is concerned with making atomic transactions perform well in the wide-area distributed systems that will be the norm in the future. The work focuses on support for consistency levels that are weaker than serializability; these levels are of interest because many applications do not require full serializability and can achieve better performance by running at weaker levels. Some consistency levels have been defined in the past, but the earlier definitions are inadequate because they either do not rule out undesirable behaviors, or they limit implementation techniques unnecessarily. In particular they do not allow optimistic techniques, which is unfortunate because these are the best for wide area and mobile systems. This research provides definitions of existing levels that are both constrained enough to rule out bad behaviors and permissive enough to allow a wide range of concurrency control mechanisms. In addition the research defines a number of useful new levels. Furthermore, the research develops optimistic implementations of the weak levels, and uses simulation and implementation to investigate the performance advantages that can be achieved by running at weaker levels. The research will lead to precise definitions of new and old weak levels, to a set of new, optimistic implementations of the levels, and to a thorough understanding of the performance benefits that derive from weaker levels. http://www.pmg.lcs.mit.edu

本研究关注的是使原子事务在广域分布式系统中表现良好，这将是未来的规范。这项工作的重点是支持的一致性水平比串行化弱，这些水平是感兴趣的，因为许多应用程序不需要完全串行化，可以通过运行在较弱的水平，以实现更好的性能。过去已经定义了一些一致性级别，但是早期的定义是不充分的，因为它们要么没有排除不希望的行为，要么不必要地限制了实现技术。特别地，它们不允许乐观的技术，这是不幸的，因为这些技术对于广域和移动的系统是最好的。这项研究提供了现有级别的定义，既有足够的约束，以排除不良行为，并允许足够的并发控制机制。此外，该研究还定义了一些有用的新水平。此外，该研究开发了乐观的实现弱的水平，并使用模拟和实施调查的性能优势，可以通过运行在较弱的水平。该研究将导致新的和旧的弱水平的精确定义，一组新的，乐观的水平实现，并从较弱的水平得到的性能优势的透彻理解。 http://www.pmg.lcs.mit.edu