【作者】 张立地；

【导师】 曾致远； 杨峰；

【作者基本信息】 华中科技大学 ， 系统分析与集成， 2007， 硕士

【摘要】 电网调度员培训仿真系统(Dispatcher Training Simulator,简称DTS)是一套运用先进计算机技术模拟实际电网运行,用于电网调度员培训的数字仿真系统。内存数据库系统(Main Memory Database System,简称MMDBS)对整个DTS的实时数据进行存储和管理,并为DTS中其它功能模块提供数据通信支持,是DTS系统的核心模块。随着DTS系统功能的扩展,对内存数据库运行效率的要求越来越高。在MMDB中主要靠两个途径来提高性能。第一改变数据库存储结构,减少查找数据带来的开销;第二选择合适的并发策略来适应并发操作。论文结合DTS系统的特点,通过对基于树的和基于Hash的索引技术的深入研究,提出了带冲突链的可扩展Hash索引与T-树索引在内存数据库中的应用,并给出相应算法的实现方法;在并发控制方面,针对DTS系统中各种实时事务的特点,对两阶段封锁协议(2PL)进行了研究,并分析了有序共享锁算法(2PL-OS)在内存数据库中的应用。由于2PL-OS存在串联夭折问题,在DTS内存数据库中采用2PL-OS/ACA(Avoiding Cascading Abort)并发策略,既保持了有序共享的特性,又避免了读脏数据。结合南阳DTS系统项目开发的实际需求,DTS内存数据库(DTS-MMDB)采用客户端/服务器(Client/Server)设计模式,采用2PL-OS/ACA并发策略与快照思想相结合,实现了多用户并发访问。最后,对论文所做的全部工作进行了总结,提出了目前设计中的创新点及不足之处,并对未来DTS-MMDBS索引技术与并发控制技术予以展望。更多还原

【Abstract】 Dispatcher Training Simulator (DTS) is a kind of real-time simulate system that is used for power dispatcher training. DTS can simulate the running state of real power system by using computer technology. Memory Database System (MMDBS) is the core module, which is in charge of real-time data storage and management and providing data communications support for other modules of DTS. With the rapid expanse of DTS’functions, it demands the MMDBS to be more and more efficient and reliable.MMDB improves its performance mainly by two ways. The first way is changing the database structure to reduce the costs of searches; the second choice is choosing suitable strategies to meet with concurrent control.By analyzing the characteristics of DTS, this paper proposes Extendible Hashing with conflict chains and T-tree index algorithm after deep studying on indexing technology based on tree structure and hash technology; In concurrency control, according to real-time feature of the system, the paper analyzes the two-phase locking protocol (2PL)and the applications of 2PL-Ordered Sharing (2PL-OS) in MMDB. To cope with the transaction‘s cascading abort problem in 2PL-OS, 2PL-OS/ACA (Avoiding Cascading Abort) is used in DTS-MMDB, which maintains the characteristics of ordered sharing and avoiding reading dirty data.Combined the actual demand for Nanyang’s DTS project, Client/Server design pattern is used in DTS-MMDB. The real-time transactions are adopted 2PL-OS/ACA strategy and snapshot, and the system implementes multi-user concurrent access.Finally, the paper makes a review of above work, proposes the innovations and inadequate of current design, and makes the future prospects of indexing technology and concurrency control technology in DTS-MMDBS.更多还原