Empirical Data Reference Behavior in Data Base Systems

During the past several years a considerable amount of effort has gone into the measurement, analysis, and modeling of program behavior. Most of the work either assumes the existence of a reference string, which is then used in various ways, or attempts to produce a model for the process by which such reference strings are generated. With very few exceptions the reference strings that have been measured characterize virtual memory utilization, reflecting the fact that the motivating force behind these research activities is the desire to understand the behavior of virtual memory paging systems.     

数据库安全与安全数据库管理系统设计

过去的十几年中,许多专家学者在数据库安全领域作了大量的研究工作,取得了不少研究成果,其中有些成果已经运用到商品化的安全数据库产品中.本文首先介绍了数据库安全的重要意义和评估安全数据库的相关标准,讨论了保证数据库安全的机制,并进一步研究了实现安全数据库所应考虑的各方面问题,包括建立数据库安全模型、实施存取控制策略、数据加密、审计与攻击检测等.最后给出了几个安全数据库研究原型和产品.     

基于对象的关系数据库管理系统的设计与实现

对象关系数据库技术是在继承关系数据库技术的基础上,增加面向对象特性,可满足GIS等应用领域的需求而发展起来的一种新型数据库技术,它既具有管理复杂数据的能力,又能提供强有力的查询功能。本文基于面向对象的关系数据库管理系统,提出直接在对象关系数据库中存储矢量地理时空数据的方法,实现了空间数据、时间数据和属性数据的一体化管理。     

基于对象的关系数据库管理系统的设计与实现

对象关系数据库技术是在继承关系数据库技术的基础上,增加面向对象特性,可满足GIS等应用领域的需求而发展起来的一种新型数据库技术,它既具有管理复杂数据的能力,又能提供强有力的查询功能。本文基于面向对象的关系数据库管理系统．提出直接在对象关系数据库中存储矢量地理时空数据的方法,实现了空间数据、时间数据和属性数据的一体化管理．     

Reorganizing the files in Data Base Management Systems

A model of Data Base Management System (DBMS) including features of dynamic reorganization of files is presented. A controlled Markov chain is assumed to describe environment changes of the DBMS. The problem of optimal reorganization of the files is presented in terms of dynamic programming.     

影响分布式数据库系统数据存取效率的因素

论述了分布式数据库环境对数据通信的要求 ;对影响分布式数据库系统数据存取效率的因素进行了探讨。     

数据库管理系统中数据异常体系化定义与分类

数据异常尚没有统一的定义,其含义是指可能破坏数据库一致性状态的特定数据操作模式.已知的数据异常有脏写、脏读、不可重复读、幻读、丢失更新、读偏序和写偏序等.为了提高并发控制算法的效率,数据异常也被用于定义隔离级别,采用较弱的隔离级别以提高事务处理系统的效率.体系化地研究了数据异常以及对应的隔离级别,发现了22种未被其他文献报告过的新的数据异常,并对全部数据异常进行分类.基于数据异常的分类,提出了新的且不同粒度的隔离级别体系,揭示基于数据异常定义隔离级别的规律,使得对于数据异常和隔离级别等相关概念的认知可以更加简明.     

A Survey of Developments in Distributed Data Base Management Systems

Distributed data base management systems extend the capacities of computing systems to give many people access to a wide range of information. These systems, which arise from the combination of recent important advances in computer networks with general-purpose data base management systems, should shortly represent another significant step in commercial system development. So it is not surprising that they have been the focus of much research and development activity in both the academic and industrial environments.     

The Information Systems Plan and the Data Base Plan

The data base management system (DBMS) is becoming the heart of modern information system architectures. To take full advantage of a DBMS's data sharing potential, the MIS manager must carefully analyze systems implementation priorities. An information systems plan (ISP) provides the data administration staff with valuable input that aids in determining the appropriateness of applications for the DBMS and in establishing a logical, phased implementation schedule. An ISP can also prove valuable to data administration in preparing and executing a data base plan.     

Data Base Interfaces

We often read about the need for better data base interfaces. But what precisely is meant by data base interfaces, and what constitutes better? This lack of precision can result in wrong solutions being promoted for real problems —or good solutions that may only solve part of the problem. The development of a better interface demands that data base designers and imple-mentors understand the varied nature of data base interfaces and match improvement goals to these interfaces in meaningful and practical ways.     

地理信息系统中的数据库技术

地理信息系统(GIS)在国民经济的发展中具有重要作用,是国民经济发展重大决策的有力工。由于在GIS系统中既有几何(空间、图形)数据,又有特征数据,而且对数据的存储和组织以及询又有不同的要求,因此,虽然关系、复杂对象和面向对象三     

New Directions for Systems: A Report Data Base from the 1984 NYU Symposium

The MIS organization is busy with the constant pressure of implementing new systems, making enhancements to existing systems, and maintaining programs, not to mention handling daily production processing and service problems. Unfortunately, it is often too busy to take a good look at its own internal operations and costs. Reviewing the internals of MIS will bolster its image, provide productivity improvements, and demonstrate that MIS is indeed a progressive organization.     

Relational Data Base Machines

Relational data base machines using head-per-track disk technology or its electronic equivalent can move processing logic closer to the data, providing simplified storage organizations for large-scale applications.     

Data Base Machines are Coming, Data Base Machines are Coming!

New research efforts and recent advances in hardware technology may soon make the commercial data base machine a reality.     

多机器人系统的研究现状

介绍了多机器人系统的研究进展及现状,对该领域内的主要内容(思想源泉、体系结构与控制、通信、学习、可重构机器人)的研究现状作了分析和介绍,还提出了一些未来值得研究的议题。     

Trends in Data Organization and Access Methods

There has been a trend in applications programming over the past fifteen years from highly structured programs and loosely structured data toward loosely structured programs and highly structured data. Transaction oriented systems and other data directed programs make greater demands on the memory hierarchy of a computer system and have given rise to the need for storage media which are to some degree structurable under program control. Overhead in operating systems and large on-line application programs is described as a symptom of "static" and "dynamic" mismatch problems in the storage hierarchy. Some new memory organization techniques beginning to appear on computers may allow greater efficiency in data directed systems since they allow the programmer to store the structure and the content of his data separately.