XML数据库的树模型抽象及其查询

在XML的树模型基础上，提出查询是一个有序的带标记树、数据库是一个有序的带标记树集合的思想，对于查询的回答是一个或几个从查询树结点到数据库结点的同态映射；对一般意义下的XML树模型进行了形式化改造，并且基于改造后的XML树模型构造了查询；最后，阐述了这一工作的意义。     

XML数据库查询及优化研究

随着网络信息的大量涌现和广泛应用,原来简单的信息发布技术已经不能满足必需的信息交流与共享,XML(eX tensibleMarkupLanguage)的出现似乎为上述问题的解决提供了转化。随着XML技术的不断成熟,要构建基于XML的各种应用,从XML数据源中准确有效地查询所需信息,也就变得越来越重要。文中对XML数据库查询语言及对半结构化数据查询、转换输出、数据集成、XML数据索引、结构模糊查询展开分析,详细探讨了XML查询语言的特点、模式、处理过程和查询优化等技术。     

XML数据库查询及优化研究

随着网络信息的大量涌现和广泛应用,原来简单的信息发布技术已经不能满足必需的信息交流与共享,XML(eXtensible Markup Language)的出现似乎为上述问题的解决提供了转化.随着XML技术的不断成熟,要构建基于XML的各种应用,从XML数据源中准确有效地查询所需信息,也就变得越来越重要.文中对XML数据库查询语言及对半结构化数据查询、转换输出、数据集成、XML数据索引、结构模糊查询展开分析,详细探讨了XML查询语言的特点、模式、处理过程和查询优化等技术.     

Native XML数据库关键技术综述

Native XML数据库是一种根据XML数据的特点专门设计的用于存储和管理XML数据的新型数据库.在介绍Native XML数据库系统的特征和体系结构的基础上,对其存储机制、索引和查询技术、事务管理等关键技术进行了深入细致的研究和讨论,最后针对具体的Native XML数据库系统在这些方面的实现机制作了相应的对照和分析.     

基于关系型数据库的XML查询系统设计

主要讨论支持XQuery语言的XML数据库的关键问题.在关系数据库中存储XML数据,采用的方法是基于模式的方法.进一步,基于以关系形式存储的XML数据,提出一种通用的基于XQuery数据模型的方法支持XQuery.     

XML关键字查询处理研究

关键字查询作为一种有效的信息检索手段,一直以来都是XML数据管理领域研究的热点问题,每年均有大量最新研究成果出现在各种顶级会议和期刊上.针对众多国内外研究者在XML关键字查询领域所作出的创新性工作,该文以XML关键字查询处理系统为框架来组织现有工作,重点分析和比较了查询生成、语义定义、排序机制、查询算法及结果展示等5个关键技术点所涉及的代表性工作的特点,并结合最新的应用需求从有效性和高效性的角度归纳出XML关键字查询技术后续研究面临的问题和挑战.     

外包XML数据库查询验证技术

外包XML数据库的查询验证目标是保证XML数据和结构的可信性.为此,设计一种基于RMH树的数据结构,改进现有查询验证算法,对XML数据和结构进行真实性、完整性和最新性的验证,并且使数据的完整性验证具有隐私保护功能.理论分析和实验结果表明,该方案在查询验证效率、存储成本、安全性等方面均优于现有验证方案.     

基于XML的汽车零部件查询系统的研究和设计

在一个汽车零部件信息查询系统的基础，从一个侧面对基于XML存储的具有语义特征的Web信息的存储、索引和查询进行了研究，通过把XML和传统的DBMS技术结合起来，提出了一种新的实现方法。     

基于XML数据库Tamino的Web应用系统的设计

简单介绍了XML文档的结构特点,详细论述了用于存储XML数据的Native-XML数据库的技术特点,并应用XML数据库Tamino Database,设计广州金融货币博物馆电子化的Web应用系统.     

标签劣质的XML数据上的查询处理

XML数据中的不正确数据、不一致数据、不精确数据等劣质数据给XML数据上的有效查询处理带来了挑战。重点研究了标签劣质的XML数据上twig查询的处理方法。给出求得每个标签的拼写相近标签、松弛标签、同义标签等相似标签的方法,以及在XML文档中求出与原查询相似的所有查询结果的高效算法。通过实验证明了所提方法的有效性和效率。     

RPE query processing and optimization techniques for XML databases

An extent join to compute path expressions containing parent-children and ancestor-descendent operations and two path expression optimization rules, path-shortening and path-complementing, are presented in this paper. Path-shortening reduces the number of joins by shortening the path while path-complementing optimizes the path execution by using an equivalent complementary path expression to compute the original one. Experimental results show that the algorithms proposed are more efficient than traditional algorithms.     

分布式数据库中查询处理的新方法研究

在分布式数据库系统中,由于数据的分布和冗余,使得分布式查询处理增加了许多新的内容和复杂性,通过分析现有分布式数据库查询处理技术,根据应用实际提出一种新的查询处理方法,该方法通过将常用查询结果存储在本地来减少查询时的数据传输量,从而缩短了响应时间.实验证明了该方法是有效的.     

Extending path summary and region encoding for efficient structural query processing in native XML databases

Optimizing query processing is always a challenging task in the XML database community. Current state-of-the-art approaches focus mainly on simple query. Yet, as the usage of XML shifts towards the data-oriented paradigm, more and more complex query processing needs to be supported. In this paper, we present TwigX-Guide, a hybrid system, which takes advantage of the beautiful features of path summary in DataGuide and region encoding in TwigStack to improve complex query processing. Experimental results indicate that TwigX-Guide can process complex queries on an average 38% better than the TwigStack algorithm, 31% better than TwigINLAB, 11% better than TwigStackList and about 9% better than TwigStackXB in terms of execution time.     

面向对象的XML查询系统的设计与实现

设计和开发了面向对象的XML数据查询系统原型OOX(object-oriented XML).OOX系统中包括了面向对象XML数据查询系统的一些核心功能,如存储、索引、查询等.其最大的特点是:它是一个可以实现对富含面向对象XML数据进行查询的XML查询系统;支持用继承扩展的XML模式语言DTD的解析,支持用继承扩展的XML查询语言XML-RL;采用了先进的路经仓索引模式以及高效的查询处理技术,可以实现高效的查询处理.     

Native XML数据库的文档编码机制研究

Native XML数据库快速查询的实现,可以采用基于XML文档编码的结构连接算法。而结构连接算法的实现需要对XML文档进行编码,以便于快速判断XML文档树结点之间的祖先后裔关系。在对现有编码机制进行综述的前提下,提出一种新的XML文档编码机制——前缀整除编码（PDIV）机制。该机制编码形式简单,只需要一个正整数即可充分表示结点在XML文档树中的位置信息;可以实现祖先后裔关系的快速查询;支持XML文档的更新操作;编码长度较短,编码长度约为o（ln（n））。     

Natural language query processing in a temporal database

This paper addresses some of the issues that arise in representing temporal information in the database context. It deals not only with the explicit representation of temporal information but with mechanisms for reasoning with it as well. It addresses the issue of processing natural language queries with explicit temporal references. The three issues of knowledge representation, natural language processing and query processing are addressed using the axiomatic framework based on equational logic.     

Efficiently supporting order in XML query processing

XML is an ordered data model and XQuery expressions return results that have a well-defined order. However, little work on how order is supported in XML query processing has been done to date. In this paper we study the issues related to handling order in the XML context, namely challenges imposed by the XML data model, the variety of order requirements of the XQuery language, and the need to maintain order in the presence of updates to the XML data. We propose an efficient solution that addresses all these issues. Our solution is based on a key encoding for XML nodes that serves as node identity and at the same time encodes order. We design rules for encoding order of processed XML nodes based on the XML algebraic query execution model and the node key encoding. These rules do not require any actual sorting for intermediate results during execution. Our approach enables efficient order-sensitive incremental view maintenance as it makes most XML algebra operators distributive with respect to bag union. We prove the correctness of our order encoding approach. Our approach is implemented and integrated with Rainbow, an XML data management system developed at WPI. We have tested the efficiency of our approach using queries that have different order requirements. We have also measured the relative cost of different components related to our order solution in different types of queries. In general the overhead of maintaining order in our approach is very small relative to the query processing time.     

Dynamic interval-based labeling scheme for efficient XML query and update processing

XML data can be represented by a tree or graph structure and XML query processing requires the information of structural relationships among nodes. The basic structural relationships are parent-child and ancestor-descendant, and finding all occurrences of these basic structural relationships in an XML data is clearly a core operation in XML query processing. Several node labeling schemes have been suggested to support the determination of ancestor-descendant or parent-child structural relationships simply by comparing the labels of nodes. However, the previous node labeling schemes have some disadvantages, such as a large number of nodes that need to be relabeled in the case of an insertion of XML data, huge space requirements for node labels, and inefficient processing of structural joins. In this paper, we propose the nested tree structure that eliminates the disadvantages and takes advantage of the previous node labeling schemes. The nested tree structure makes it possible to use the dynamic interval-based labeling scheme, which supports XML data updates with almost no node relabeling as well as efficient structural join processing. Experimental results show that our approach is efficient in handling updates with the interval-based labeling scheme and also significantly improves the performance of the structural join processing compared with recent methods.     

基于系统表的通用动态查询系统设计与实现

介绍了开发C/S模式下的基于系统表的数据库信息通用动态查询系统的设计思路和实现.在深入研究系统表和SQL语法的基础上,将查询需求与查询软件相分离,使软件相对通用,与具体应用无关,与库结构变更无关.软件使用方便,查询需求变化无需修改软件,只需在数据库服务器端编写相关视图,节省了大部分情况下查询需求的开发成本和后续的维护成本.     

Native XML数据库的结构连接算法研究

Native XML数据库的快速查询,可以通过基于XML文档编码的结构连接算法实现。在对现有结构连接算法进行综述的前提下,提出一种新的Native XML数据库的结构连接算法——基于深度均匀划分的结构连接算法(DRIAM)。该算法不要求输入数据AList和DList有序或在其节点编码上建有索引,避免了排序和索引所增加的额外开销;不需要输入数据AList和Dlist全部加载到内存中,可以适应不同内存大小限制的情况,并且该算法时间复杂度非常低。