Establishing Dynamic Cost Models for Multidatabase Systems

建立多数据库系统的动态成本模型

• 批准号: 9811980
• 负责人: Qiang Zhu
• 金额: $ 17.66万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-15 至 2002-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9811980&HistoricalAwards=false
• 关键词: Establishing; Dynamic; Cost; Models; Multidatabase

A crucial challenge for global query optimization in a multidatabase system is that some required local information such as local cost models may not be available at the global level due to local autonomy. A number of techniques to tackle this challenge have been suggested in the literature recently. However, they are suitable only for a static system environment. This research project explores theory and methods to establish dynamic cost models for a multidatabase system. Previous work on a query sampling method for establishing cost models in a static system environment is extended to a dynamic system environment. The methodologies adopted in this project include a qualitative approach, which introduces qualitative variables into cost models, and an adaptive approach, which adaptively incorporates dynamic cost information observed from execution of user queries into cost models. All approaches are evaluated and compared in order to determine the most promising one to establish dynamic cost models for multidatabase systems. Theoretical and experimental studies on query optimization that takes advantage of dynamic cost models are also conducted. The project will provide theory, algorithms, and implementation techniques for the design and development of an efficient multidatabase system.

多数据库系统中全局查询优化的一个关键挑战是，由于局部自治，一些必需的本地信息（如本地成本模型）可能无法在全局级别上使用。最近的文献中提出了许多解决这一挑战的技术。然而，它们只适用于静态系统环境。本课题探讨了建立多数据库系统动态成本模型的理论和方法。将以往在静态系统环境中建立成本模型的查询抽样方法推广到动态系统环境中。本项目采用的方法包括定性方法（将定性变量引入成本模型）和自适应方法（将从用户查询执行中观察到的动态成本信息自适应地纳入成本模型）。对各种方法进行了评价和比较，以确定最适合建立多数据库系统动态成本模型的方法。对利用动态代价模型的查询优化进行了理论和实验研究。该项目将为设计和开发高效的多数据库系统提供理论、算法和实现技术。