一种Xquery查询的表示模型

本文介绍了一种Xquery查询的表示模型，用户根据需要的单个的结果元素或XML片断建立原子查询，递归应用Nest、Join、Merge等合成操作将原子查询逐步合成出复杂的查询表达式，从而实现简化用户查询表达式的建立过程。     

基于语义的XML关键字查询

针对XML数据的关键字查询问题,考查了已有的查询技术的优势和不足,提出了基于语义的XML关键字检索算法。对用户输入的关键字进行分类,分为条件关键字和结果关键字。条件关键字只用于限定查询范围,不出现在结果集中。给出了语义相关节点对的概念和判定方法,并提出了基于关键字分类和语义相关节点对的XML数据查询算法。     

XML信息检索中基于反馈的查询扩展分析

XML信息检索中,提高检索准确率的有效途径就是基于反馈机制的用户查询扩展。根据反馈机制的不同,文章对国内外研究XML查询扩展的文献进行了分类分析,重点分析、比较了几篇有影响文献的扩展方法和实验结果。在深入分析的基础上提出了当前研究中存在的几点不足,并对未来的研究工作作出了一些简单的预测和展望。     

XML数据查询处理和优化策略研究

XML是互联网上数据表示和数据交换的标准。随着大量XML数据的出现,如何有效的查询XML文档内容是值得深入研究的问题。本文阐述了查询XML数据最常用的XPath表达式和XQuery查询语言两种方法,并针对XML查询处理技术和XML查询优化技术进行了详细的探讨,通过对小枝查询的选择度估算问题研究,实现提高XML数据查询性能和执行效率。     

面向XML的语义近似检索模型

针对XML文档检索的特点,提出了一种基于XSEarch引擎的语义近似检索模型。设计了利用WordNet对查询项进行语义扩展的计算方法,且对XSEarch引擎的答案排序模型进行了改进,并提出了满足近似检索模型的系统体系结构。     

XML与关系数据库数据的转换的研究

XML数据库等已经开始迅速发展．但是这些新挂术在现阶段仍然不很成熟，目前对XML数据的普遍处理方法是将其转换成关系格式，以便利用目前成熟的关系数据库枝术进行存储和查询。文章讨论了XML文档与关系型数据库之间的关系，并介绍了如何将XML文件数据与关系数据库数据转换的具体实现。     

基于SQL Server的XML数据技术

随着大量XML数据的出现,如何有效地存储、管理和查询这些XML数据已成为一个值得研究的重要课题,目前,XML数据库技术是数据库领域的研究热点。而作为SQL Server可以实现XML数据格式的转变,SQL Server实现XML的数据格式,用户就可以更有效地更新和读取数据了,从而不需要将XML数据转换成数据库可以理解的另一种格式,开发人员在访问数据时就会非常灵活和方便。本文围绕如何基于SQL Server实现XML数据格式的技术做了探讨。     

SQL 2005处理XML半结构化数据查询

SQLScrver2005关系数据库管理系统提供了强大的管理XML数据的功能,但它用传统的通过建立索引等方式进行查询效果并不理想.文章分析了SQLserver2005在查询XML数据过程中低效的原因,提出了通过建立附加表或者附加列以及相应索引、利用查询窗口等措施来优化查询.实验结果表明,该方法能有效提高查询XML数据的效率.     

WEBSOM——一种新的网络信息组织方法

WEBSOM是一种基于SOM(Self-organizing Map)算法的全文本信息组织与检索方法[1-3].它根据一定的语义关系对特定数据库中的纯文本文献进行自动组织,形成一个有序的数据空间,并将该空间中的元素关系投影到一个二维平面上,形成一个可视地图,供用户浏览查询.     

非一致数据库的查询研究

提出的方法能灵活地进行数据库SQL查询,它可以干扰一系列的约束条件,并且这种方法能够允许用户假定一组约束和查询一起。系统重写这个查询去查找相应的与约束一致的数据。这个重写是SQL,以便能被商业数据库系统有效地优化和执行。使用TPC-H基准的数据和查询比较脏数据多粒度的执行性能,实验显示该方法是可行的。     

Managing structured queries in probabilistic XML retrieval systems

Focusing on the context of XML retrieval, in this paper we propose a general methodology for managing structured queries (involving both content and structure) within any given structured probabilistic information retrieval system which is able to compute posterior probabilities of relevance for structural components given a non-structured query (involving only query terms but not structural restrictions). We have tested our proposal using two specific information retrieval systems (Garnata and PF/Tijah), and the structured document collections from the last six editions of the INitiative for the Evaluation of XML Retrieval (INEX).     

Temporal and multi-versioned XML documents: A survey

Extensible Markup Language (XML) documents are associated with time in two ways: (1) XML documents evolve over time and (2) XML documents contain temporal information. The efficient management of the temporal and multi-versioned XML documents requires optimized use of storage and efficient processing of complex historical queries. This paper provides a comparative analysis of the various schemes available to efficiently store and query the temporal and multi-versioned XML documents based on temporal, change management, versioning, and querying support. Firstly, the paper studies the multi-versioning control schemes to detect, manage, and query change in dynamic XML documents. Secondly, it describes the storage structures used to efficiently store and retrieve XML documents. Thirdly, it provides a comparative analysis of the various commercial tools based on change management, versioning, collaborative editing, and validation support. Finally, the paper presents some future research and development directions for the multi-versioned XML documents.     

Querying XML documents using Prolog engines: When is this a good idea?

XML has become a universal standard for information exchange over the Web due to features such as simple syntax and extensibility. Processing queries over these documents has been the focus of several research groups. In fact, there is broad literature in efficient XML query processing which explore indexes, fragmentation techniques, etc. However, for answering complex queries, existing approaches mainly analyze information that is explicitly defined in the XML document. A few work investigate the use of Prolog to increase the query possibilities, allowing inference over the data content. This can cause a significant increase in the query possibilities and expressive power, allowing access to non-obvious information. However, this requires translating the XML documents into Prolog facts. But for regular queries (which do not require inference), is this a good alternative? What kind of queries could benefit from the Prolog translation? Can we always use Prolog engines to execute XML queries in an efficient way? There are many questions involved in adopting an alternative approach to run XML queries. In this work, we investigate this matter by translating XML queries into Prolog queries and comparing the query processing times using Prolog and native XML engines. Our work contributes by providing a set of heuristics that helps users to decide when to use Prolog engines to process a given XML query. In summary, our results show that queries that search elements by a key value or by its position (simple search) are more efficient when run in Prolog than in native XML engines. Also, queries over large datasets, or that searches for substrings perform better when run by native XML engines.     

基于ADO.NET的XML与SQL Server 2000数据交换研究与应用

介绍了XML的概念和一些特点，分析了XML和SQL Server2000数据交换的几种方式，以及在SQL Server2000中，使用SELECT语句可以把查询结果存储为XML文档，使用OPENXML语句提供了在关系数据库表中存储XML文档的功能，并实际实现了SQL Server2000和XML之间的数据交换。     

Efficient probabilistic XML query processing using an extended labeling scheme and a lightweight index

Recently there is a growing interest in the data model and query processing for probabilistic XML data. There are many potential applications of probabilistic data, and the XML data model is suitable to represent hierarchical information and data uncertainty of different levels naturally. However, the previously proposed probabilistic XML data models and query processing techniques separate finding data matches with evaluating the probabilities of results. Therefore, they should repeatedly access the data and need to get full data of paths given in queries to calculate the probabilities of results.     

Descendants,ancestors, children and parent: A set-based approach to efficiently address XPath primitives

XML is a pervasive technology for representing and accessing semi-structured data. XPath is the standard language for navigational queries on XML documents and there is a growing demand for its efficient processing.In order to increase the efficiency in executing four navigational XML query primitives, namely descendants, ancestors, children and parent, we introduce a new paradigm where traditional approaches based on the efficient traversing of nodes and edges to reconstruct the requested subtrees are replaced by a brand new one based on basic set operations which allow us to directly return the desired subtree, avoiding to create it passing through nodes and edges.Our solution stems from the NEsted SeTs for Object hieRarchies (NEASTOR) formal model, which makes use of set-inclusion relations for representing and providing access to hierarchical data. We define in-memory efficient data structures to implement NESTOR, we develop algorithms to perform the descendants, ancestors, children and parent query primitives and we study their computational complexity.We conduct an extensive experimental evaluation by using several datasets: digital archives (EAD collections), INEX 2009 Wikipedia collection, and two widely-used synthetic datasets (XMark and XGen). We show that NESTOR-based data structures and query primitives consistently outperform state-of-the-art solutions for XPath processing at execution time and they are competitive in terms of both memory occupation and pre-processing time.     

数字图书馆中基于XML的搜索引擎设计

数字图书馆在WWW上进行相应的信息展示与提供，基于HTML的文档标记使信息查寻遇到了很大的挑战。本文提出了基于XML的搜索引擎逻辑结构，并对其中的关键技术进行了研究，提出了对XML半结构化文档建立索引和查寻时采用的数据结构和算法，使得数字图书馆在WWW上开展深层次信息提供成为可能，并且也使图书馆原有的MARC信息资源能得到充分利用。     

XML技术在网络购物平台信息处理中的应用

XML技术的应用非常广泛，可以用XML技术来解决Internet网络、人工智能、知识库和数据挖掘等领域的问题。本文以网络购物为实例对XML技术在电子商务的信息处理系统中的应用进行了研究，主要针对数据信息的文档类型定义、数据的存储和检索，以及用于显示的样式表进行了设计。     

基于多数据源的XQuery查询重写优化技术

本文主要阐述了XQuery对XML查询优化的相关内容,主要涉及的技术包括最小化、XML代数、索引技术、倒排列表、选择估计、重写机制等。本文阐述了其中基于多数据源的重写算法的具体思想和核心算法。