阈值上限一定时超大规模数据库的查询方法研究

在确定查询阈值上限时,当前数据库查询方法只能使用查询树的一条路径,并行性能较差;在对超大规模数据进行查询时,具有查询时间长、响应不及时的弊端。为此,提出一种新的阈值上限一定时超大规模数据库的查询方法,通过RSA算法对超大规模数据库进行加密和解密处理,依据多叉树的定义构造多叉索引树,在此基础上计算各代表数据点与查询点之间的距离;在阈值上限一定时,利用多个从节点机并行处理后,使用主节点机汇集结果,运用后续子树递归处理,直至获取查询结果。实验结果表明,所提方法不仅具有很高的查询效率,而且CPU使用率很高。     

Distributed location-based query processing on large volumes of moving items

Recently,new techniques to efficiently manage current and past location information of moving objects have received significant interests in the area of moving object databases and location-based service systems. In this paper,we exploit query processing schemes for location management systems,which consist of multiple data processing nodes to handle massive volume of moving objects such as cellular phone users. To show the usefulness of the proposed schemes,some experimental results showing performance factors regarding distributed query processing are explained. In our experiments, we use two kiids of data set：one is generated by the extended GSTD simulator and another is generated by the real-time data generator which generates location sensing reports of various types of users having different movement patterns.     

改进的空间数据库主动规则条件测试模型

空间数据库的主动规则条件测试对于规则的执行效率至关重要。本文采用空间查询代数优化技术和空间算子迁移方法,提出扩展的空间规则鉴别网络(ESRDN)模型,给出ESRDN的优化启发式规则及其正确性证明,分析结果表明,该改进模型可以提高空间数据主动规则的条件测试效率。     

SQL Sever 2000系统编程时的性能优化

SQL Sever 2000作为一种普遍应用的大型数据库管理系统，其优化技术在数据库应用中尤显重要。从减少数据传输、避免使用LIKE搜索条件、使用分组字段等方面介绍如何优化查询设计；从使用UPDATE数据库更新、使用索引、防止死锁及死锁处理等方面介绍在数据维护时的性能优化。     

FoxPro中Rushmore技术分析

本文分析了FoxPro申部分优化查询的原理,分析了它所采用的方法和技术。     

KBMDS：基于知识的地图数据库系统

ＫＢＭＤＳ是在ＭＤＳ地图数据库的基础上，结合ＡＩ技术，面向地图的基于知识的地图数据库系统，它具有四种功能：编辑功能、查询功能、学习功能和人机交互功能。系统采用了框架语义网络知识表达方法及其揄机制实现对图象物体的描述和检索，基于查询实例的学习功能提高了系统的查询效率，基于规则的图象物体描述的自动知识获取的途径。ＫＢＭＤＳ提供了两种查询语言，一种是具有二维文法的ＱＰＥ；一种是具有线性文法的ＬＩＰＬ语言     

The interoperability of distributed DBMSs in a CORBA-based multidatabase system

One way of achieving interoperability among heterogeneous, distributed DBMs is through a multidatabase system. Recently, there is an increasing use of CORBA implementation in developing multidatabase systems. Panorama is a multidatabase system that has been implemented on the top of CORBA compliant namely VisiBroker. It aims to achieve interoperability among Oracle, Sybase and other different DMBSs through the registration of these DBMSs to Panorama and through the single global query language-PanoSQL designed for this system. In this paper, we first introduce CORBA for the interoperability in multidatabase systems. Then, a general view for our designed multidatabase system. Panorama, has been given. In section four, we introduce the global query language-PanoSQL designed to achieve interoperability among the different DBMSs implemented in Panorama. Then, as an example, we present the registration of Oracle to panorama in order to achieve interoperability in this system. And, finally, a conclusion and the future work for this system have been given. Foundation item: Supported by the National High Performance Foundation of China Biography: Sarem Mudar (1966-), male, Ph.D candidate, research direction: multidatabase systems.     

An Efficient Algorithm for Query Transformation in Semantic Query Optimization

Semantic query optimization (SQO)is comparatively a recent approach for the transformation of given query into equivalent alternative query using matching rules in order to select an optimal query based on the costs of executing alternative queries,The key aspect of the algorthm proposed here is that previous proposed SQO techniques can be considered equally in the uniform cost model,with which optimization opportunities will not be missed.At the same time,the authors used the implication closure to guarantee that any matched rule will not be lost .The authors implemented their algorithm for the optimization of decomposed sub-query in local database in MultiDatabase Integrator(MDBI),which is a multidatabase project.The experimental results verify that this algorithm is effective in the process of SQO.     

一种基于虚拟数据库的分布式查询优化算法

针对虚拟数据库系统(简称“VDBMS”)执行分布式查询时的网络代价问题,提出一种基于关系运算代价估算理论及半连接技术的分布式查询优化算法SJQA(Semijoin Based Query Algorithm),较之最大子查询法,该算法加入了对子查询之间执行顺序及连接方式等方面因素的考虑,从而能更有效地减少分布式查询的总网络代价．实验结果表明,对于带有选择运算的查询,SJQA算法的优化效益与查询的选择因子大小成近似反比关系,因此它对该类查询的优化效果是十分明显的。     

以形成性评价理论为基础的网上累积分查询系统

以形成性评价理论为基础,设计并实现了一种学生成绩的网上累积分的查询系统。分析了累积分查询系统应达到的基本功能及其工作原理,详细讲解了查询系统的具体实现过程,以及一些有特色的技术。学生通过查询累积分,不仅可以随时获得课程平时成绩的详细积分,还能知道自己的累积分在班级中的水平,有利于学生及时补交、完善作业,增加同学之间的学习竞争意识,且该查询系统还能保护学生的成绩隐私。