Design of a distributed CODASYL database system

A general model for distributed database systems based on the three-level architecture is presented. How concrete architectural forms can be derived from the general model is illustrated by means of the CODASYL database model. A new language is introduced, the data partition language, in which all distribution specific statements are concentrated. The application of distribution predicates in the data partition language to form distribution units leads to the concept of a “distribution graph”—it is a subset of the schema graph and defines the validity scope of a distribution predicate. Global database keys, global currency indicators and multiple record access are suggested to manipulate distributed CODASYL databases.     

A generalized expert system for database design

Generalized Expert System for Database Design (GESDD) is a compound expert system made up of two parts: (1) an expert system for generating methodologies for database design, called ESGM; and (2) an expert system for database design, called ESDD. ESGM provides a tool for the database design expert to specify different design methodologies or to modify existing ones. The database designer uses ESDD in conjunction with one of these methodologies to design a database starting from the requirement specification phase and producing a logical schema in one of the well-known data models, namely, the hierarchical data model, the network data model, or the relational data model. The system is evolutive in the sense that an existing methodology can be modified or a novel methodology can be added to the existing ones. GESDD is a menu-driven system and it is coded in Prolog     

A microcomputer database system for facilities design

A data base management system which is dedicated to plant layout type data, and should be useful to the practicing industrial engineer, is presented. The data items utilized in the data base for this microcomputer software represent only a minimal subset of the data which one would want for the creation of a proper, industrial facility design; however, they were felt to represent a good starting point for the creation of a microcomputer data base system which would aid a layout engineer. The Knowledgeman software (Micro Data Base Systems, Inc.) was used for this project; it consists of a relational database and an electronic spreadsheet. Two plant layout examples are presented to demonstrate the use of the software.     

Estimating block selectivities for physical database design

Access path deployment is a critical issue in physical database design. Access paths typically include a clustered index as the primary access path and a set of secondary indexes as auxiliary access paths. To deploy the right access paths requires an effective algorithm and accurate estimation of the parameters used by the algorithm. One parameter central to any index-selection algorithm is the block selectivity of a query. Existing methods for estimating block selectivities are limited by restrictive assumptions. Furthermore, most existing methods produce estimates useful for aiding the selection of secondary indexes only. Little research has been done in the area of estimating block selectivities for supporting the selection of the clustered index. The paper presents a set of methods that do not depend on any specific assumption, produce accurate estimates, and can be used to aid in selecting the clustered index as well as secondary indexes     

Modeling the CODASYL DML context dependency for database program conversion

The CODASYL database (db) statements in an application program can have one or more different semantics associated with it, depending on the path through which the execution reaches that statement. This makes the CODASYL operations in a db program context dependent. The previous works on the db program conversion from the CODASYL record-at-a-time interface to the set-at-a-time interface of the relational model consider a limited class of programs where each db statement in the program is assumed to have a unique semantic interpretation. In this paper, we define a framework for analyzing the multiple semantics of the CODASYL operations and their context dependencies. We then show how the analysis can be used for converting a CODASYL db program which contains statements having ambiguous, multiply-defined semantics. The method described here allows us to convert any CODASYL db program.     

基于Web的工程物性数据库查询系统

物性数据库是进行化工计算的基础,网络工程物性数据库一方面给用户提供了一种方便快捷的查询途径,另一方面也给化工网络仿真协作实验提供了后台数据。根据三层B/S结构,采用Java语言和Access数据库系统,设计了基于Web的工程物性数据库查询系统的实现框架、具体的体系结构及技术方案,实现了常见的化学物质的26种工程物性的查询。用户可以通过网络查询各种物质的物性数据,化工网络仿真实验也能通过这一网络数据库实时的读取数据。     

基于Web的工程物性数据库查询系统

物性数据库是进行化工计算的基础，网络工程物性数据库一方面给用户提供了一种方便快捷的查询途径，另一方面也给化工网络仿真协作实验提供了后台数据。根据三层B/S结构，采用Java语言和Access数据库系统，设计了基于Web的工程物性数据库查询系统的实现框架、具体的体系结构及技术方案，实现了常见的化学物质的26种工程物性的查询。用户可以通过网络查询各种物质的物性数据，化工网络仿真实验也能通过这一网络数据库实时的读取数据。     

数据库物理自调优研究技术综述

数据库物理自调优是自管理自调优数据库中一项重要的内容,为厘清这一领域的重要研究工作,需要对关系数据库物理自调优的背景、问题界定、经典技术和研究的新问题等方面进行综述。总结了数据库物理自调优的经典技术,并从优化程度、可扩展性、可用性可管理性及测试基准四个角度重点阐述了现今数据库物理自调优的关键技术和作为研究开发热点的一些问题,指出不同的物理自调优工具在技术上的共同基础,分析评价了这些关键技术及其方法的各自特点。最后还总结了该领域近几年出现的新的研究问题,并展望了未来的研究方向。     

数据库应用系统的层次化设计方法与实现

为了满足大型数据库应用系统开发中客户需求的不断变化和个性化的要求,缩短软件开发周期,提高代码可维护性,提出了一个基于6层的软件设计方法,并描述了各层的主要功能和接口机制。在此基础上实现了一个代码生成工具,并应用于具体的工程实践中,满足了系统的快速开发和良好的适应性、扩展性要求。     

A logical design tool for relational databases

A method is presented to prevent anomalies from affecting the design of a relational database. The approach, called the logical design tool (LDT), can also be used as an educational tool for the relational database. It allows certain problems that arise when the data is manipulated to be detected during design. An overview of LDT is followed by a discussion of its functions and its application     

A new approach for image databases design

This paper focuses on the methodologies to organize and structure image databases. Conventional relational database techniques are optimized to deal with textual and numeric data; however, they are not effective to handle image data. Some progresses have been made in developing new approaches to establish and use image databases, but the applications of these approaches are very labor-intensive, error-prone, and impractical to large-scale databases. In this paper, we propose a new approach to develop the structure of a large-scale image automatically. It is an integrated approach from existing technologies for the new application where the management of image data is focused. In addition, we present a solution to data indexing for the image database with different image types.     

易通打字系统数据库设计

为了实现易通码的计算机练习和输入,运用软件工程学原理、数据库理论,使用VB6.0开发平台,结合Access2003技术设计易通打字系统软件的数据库,为易通打字系统软件的实现奠定了基础。     

数据库系统设计中的面向对象技术研究

基于面向对象技术的基本思想和开发过程,介绍了面向对象技术的实现方法.结合具体实例对面向对象技术在数据库系统结构设计和详细设计中的应用进行了详细的探讨,利用面向对象的数据库系统分析和设计方法,使用UML工具建立了具体的对象模型,给出了一种比较通用的数据库系统开发模式.使用该模式设计的系统重用性好,且易于维护,从而有效提高了数据库系统的开发质量.     

城市道路交通事故信息系统空间数据库设计

有效的空间数据库存储结构是实现以集成型数据管理方式为基础的应用系统的关键问题之一.它将决定整个系统的功能和效率.按照为用户的数据视图建模、定义实体及其关系、选择地理表达方式、匹配到Geodatabase元素、组织Geodatabase结构和制定数据库存储方案等六个步骤对城市道路交通事故信息系统之空间数据库进行了规范化设计.设计所得的空间数据库接近于其逻辑数据模型.分析结果表明,该设计方法有利于优化实现城市道路交通事故信息系统的系统功能.     

Property of separability in physical design of network model databases

We present a physical design methodology for network model databases based on the theory of separability. In particular, we present a cost model and a usage specification scheme that are suitable for describing the network model database environment. We subsequently prove that, under these usage and cost models, a large subset of practically important access structures that are available in network model database systems satisfies the conditions for separability. The theory of separability was introduced in an earlier work, in the context of relational systems, as a formal basis for partitioning the problem of designing the optimal physical database. The theory proves that, given a certain set of access structures and a usage specification scheme, the problem of optimal assignment of access structures to the entire database can be reduced to the subproblem of optimizing individual record types independently of one another. The approach we present significantly reduces the complexity of the design problem which has the potential of being combinatorially explosive. A heuristic extension of the formal methodology to the access structures not incorporated in the theory is also discussed.     

实时嵌入式系统的高速内存数据库设计

提出了在实时嵌入式系统中使用内存数据库的必要性,并设计了内存数据库中两种不同类型的表结构,线性表和哈希表.介绍了线性表和哈希表的基本特点和基本操作过程,指出了管理数据库对于内存数据库的支持作用和两者之间的数据通信机制,提出了使用通信状态机技术实现两者通信的设计思想,并介绍了状态机3要素的设计和用于通信的各种消息类型,最后通过一个表的传送过程的举例描述了通信过程的典型流程.     

Computer-aided system for the database storage structure design

An overview is given of a computer aided system for the design of a schema for a CODASYL DBMS. The system helps the designer to trade off between the conflicting objectives; short retrieval time for a user query, low database updating cost, small storage requirements, and low total cost of the system. Different relative weights can be assigned to each of the users query and update transactions, and the design objectives can be assigned different priorities. The model evaluates the performance of the database for a specified set of input parameters and finds the optimal location mode of each database record type. The designer can interactively change any of the design parameters, priority and weights while performing the analysis. The system has been tested on the design of a department store database.     

Using an entity model to drive physical database design

Logical relational database design, because of its implementation-independent nature, has been successfully formalized. Physical relational database design, because of its implementation-dependent nature, has remained largely unformalized and disconnected, not only from logical design but also from conceptual database design. The paper suggests a model for the physical design process that has proven useful in a number of practical development projects. The model demonstrates that a seamless join between conceptual, logical and physical design work is feasible. It illustrates how the process of annotating a conceptual model with physical detail provides a useful framework for driving the process of physical relational database design.