【作者】 甘秋玲；

【导师】 李陶深；

【作者基本信息】 广西大学 ， 计算机应用技术， 2005， 硕士

【摘要】 随着Internet的飞速发展,协同设计系统从局域网环境扩展到广域网的环境。并发控制机制是数据库事务管理中非常重要的一部分,其性能的优劣是衡量一个数据库系统功能强弱和性能好坏的重要标志之一。本文主要开展了支持开放式协同设计的分布式工程数据库事务管理的并发控制机制的研究,取得了以下的研究成果: (1)设计了适合于开放式协同工作环境的四层分布式工程数据库协同设计体系结构,该体系结构包括用户界面层、Web服务层、应用服务层、数据库服务层。其中,用户界面层用于为用户提供良好的接口;Web服务层负责将用户的请求用SOAP协议格式传给应用服务层;应用服务层完成对用户请求的处理和将结果传送给用户;数据库服务层用于存储协同设计的数据。 (2)在分析了协作环境下工程设计事务的特点和现有的分布式并发控制机制的不足基础上,提出一种适合于开放式协同工作环境的支持协同设计的并发控制算法——基于有序相容性多粒度的多版本两阶段锁协议,并对其正确性进行了证明。新协议将只读事务和更新事务区分开,只读事务在执行时遵守多版本时间戳排序协议,而更新事务的执行将按基于两阶段有序相容性封锁的多粒度封锁协议进行。该协议将只读事务与更新事务区分开,解决了只读事务和更新事务之更多还原

【Abstract】 With the rapid development of Internet, the cooperative design system has extended from local-area network to wide-area network. Being a very important part in transaction management of database, the quality of concurrency control is one of the key criterions in evaluating the performance of a database system. This paper focuses on studying concurrency control mechanism of transaction management in distributed engineering database that supports open, cooperative design. The achievement is as follows:(1) An architecture of four-layer distributed engineering database fit for that environment is presented. The four layers are user interface layer, Web service layer, application service layer and database service layer. The function of each layer is as follows: user interface layer supplies users with friendly interfaces; Web service layer converts the user’s request to application service layer by SOAP contract; application service layer deal with the user’s request and then sends the results to them; database service layer stores data of cooperative design.(2) Based on the analysis of the features of cooperative design transaction in open environment and the disadvantages of the present distributed concurrency control protocol, a concurrency control protocol for cooperative design transaction in open environment is proposed. It is a multiversion two-phase lock protocol based on ordered sharing multi-granularity locks and its correctness is also tested. Under the new protocol, read-only transaction and update transaction is distinguished. The former abides the multiversion timestamp ordering protocol, while that of the latter follows the multi-granularity locking mechanism based on ordered sharing locks. Under the new protocol, the conflict between read-only transaction and update transaction can be resolved , the flexibility of transaction execution can be enhanced. That is, the new protocol is fit for the engineering database that supports cooperative design.(3) What’s more, the executable algorithm of the multiversion two-phase lock protocol based on ordered sharing multi-granularity locks is also given. Based on the architecture of four-layer distributed engineering database in open environment that supports cooperative design, an experiment environment is constructed. Under such a environment, the experiment of the multiversion two-phase lock protocol based on ordered sharing multi-granularity locks is carried out and the performance of the new protocol is analyzed as well. That is, the new protocol is fit for that open environment.更多还原