共查询到20条相似文献,搜索用时 15 毫秒
1.
XML在关系数据库中的存储问题是XML研究领域中的一个重要问题。在总结多种映射方法的基础上,提出了一种方法将多个相似的XML文档进行解析,根据映射关系,生成各自的关系模式,并分析归纳出一个集成的关系模式,然后创建一个关系数据库,并在映射关系的基础上提取并存储XML文档数据到关系数据库。此方法以较为简洁的结构保存了XML文档的数据信息,其最大的特点就是不用考虑文档的模式信息(DTD,XML Schema)。并通过一个具体的实验结果来说明这种方法的有效性。 相似文献
2.
XML是网络中跨平台数据发布与交换的标准格式,它在数据库领域有着广阔的应用空间。对于基于DTD在关系数据库中存储XML文档,通过对现有映射策略的分析,提出在一种改进的映射策略,可以完整保存DTD中所包含的语义约束。 相似文献
3.
4.
XML文档架构与关系数据模型间的映射研究 总被引:6,自引:2,他引:6
XML逐渐成为Internet上数据描述和交换的标准。随着Web上大量数据用XML文档表示出来,有必要对这些XML文档进行操纵管理。为了结合关系数据库系统强大的数据操纵能力,论文在对XML文档的逻辑结构进行简要介绍的基础上,就XML文档特别是结构化XML文档与关系数据模型数据之间的互动映射作了深入探讨,特别是在数据结构和数据完整性约束条件的映射关系上作了更深一层的研究,提出了一系列基于XML本身的映射规则。 相似文献
5.
6.
7.
Integrating XML and Relational Database Systems 总被引:2,自引:1,他引:2
Relational databases get more and more employed in order to store the content of a web site. At the same time, XML is fast emerging as the dominant standard at the hypertext level of web site management describing pages and links between them. Thus, the integration of XML with relational database systems to enable the storage, retrieval, and update of XML documents is of major importance. Data model heterogeneity and schema heterogeneity, however, make this a challenging task. In this respect, the contribution of this paper is threefold. First, a comparison of concepts available in XML schema specification languages and relational database systems is provided. Second, basic kinds of mappings between XML concepts and relational concepts are presented and reasonable mappings in terms of mapping patterns are determined. Third, design alternatives for integrating XML and relational database systems are examined and X-Ray, a generic approach for integrating XML with relational database systems is proposed. Finally, an in-depth evaluation of related approaches illustrates the current state of the art with respect to the design goals of X-Ray. 相似文献
8.
RDBMS中层次查询结果的XML文档生成 总被引:1,自引:1,他引:0
数据库应用系统中相当多的数据都呈现出相应的层次特征,对这类数据,常常需要生成元素间保持层次特征的XML文档,用一般的查询机制来解决这个问题比较繁琐,以Oracle9i数据库第2版为例,应用层次查询,并结合OracleXML DB,对层次查询结果相对应的保持层次特征的XML文档的生成机制进行了研究,并将其应用于税务信息综合查询系统之中.结果表明,该方法简单、效率高、应用效果良好. 相似文献
9.
对于基于DTD在关系数据库中存储XML文档,此处利用结点模型映射方法,实现用关系模式来表示目标XML文档的逻辑结构(即 XML模式或DTD).还介绍了如何在已建立好的关系模式中添加约束用来保持原有XML文档中隐含的约束信息,此外XML文档的元素之间通常是相互递归的,这里也对XML文档中在出现递归的情况时,如何来存储递归的XML文档进行说明.最后通过举例,证明此种方法是合理有效的. 相似文献
10.
XML在关系数据库中的存储问题是XML研究领域中的一个重要问题。该文在总结多种影射方法的基础之上,提出了一个利用DTD文档,在关系数据库中通过多阶段XML文档信息的提取与变换,最终实现XML模式到关系模式的影射。该文对于影射中的一些难点问题,如集合值的影射、递归元素的影射、关系表的分散等方面提出了解决办法,实现了一个较为完整、高效的影射方案。 相似文献
11.
《Information and Software Technology》2003,45(6):335-355
The revolution of XML is recognized as the trend of technology on the Internet to researchers as well as practitioners. Companies need to adopt XML technology. With investment in the current relational database systems, they want to develop new XML documents while running existing relational databases on production. They need to reengineer the relational databases into XML documents with constraints preservation. In the process, schema translation must be done before data conversion. Since the existing relational databases are usually normalized, they have to be reconstructed into XML document tree structures. This can be accomplished through denormalization by joining the normalized relations into tables according to their data dependencies constraints. The joined tables are mapped into DOMs, which are then integrated into XML document trees. The user specifies an XML document root with its relevant nodes to form a partitioned XML document tree to meet their requirements. The selected XML document tree is mapped into an XML schema in the form of DTD. We then load joined tables into DOMs, integrate them into a DOM, and transform it into an XML document. 相似文献
12.
从DTD映射到关系模式:一种保持数据依赖的映射方法 总被引:9,自引:0,他引:9
XML正迅速成为互联网上数据表示和交换的标准.用关系数据库存储XML数据是XML存储策略之一.为了将XML数据存储到关系数据库中,人们研究了从DTD到关系模式的映射方法.提出了一种保持数据依赖的映射方法PDD.与已有的Shared—Inlining方法相比,PDD方法充分考虑了DTD蕴涵的数据依赖关系,保证了XML文档的完整性.通过对泛关系进行模式分解,得到的关系模式保持函数依赖,并且满足2NF.可以证明,这种方法是有效的. 相似文献
13.
XML正迅速成为互联网上数据表示和交抉的标准,用关系数据库存储XML数据是XML存储策略之一。为了将XML数据存储到关系数据库中,人们研究了很多从DTD到关系模式的映射方法。Hybrid Inlining方法是一种比较常用的映射方法,此方法将多个元素内联到一个表中,从而可以降低查询时连接操作的次数,但同时也存在一些诸如删除异常、插入异常的问题。本文将Hybria Inlining方法运用在从Schema到关系模式的转抉中,同时在Hybrid Inlining方法的基础上做进一步改进,从而解决删除、插入异常等问题。最后给出其具有无损连接性以及锨持函数依赖的证明。 相似文献
14.
Storing and querying XML documents using a RDBMS is a challenging problem since one needs to resolve the conflict between the hierarchical, ordered nature of the XML data model and the flat, unordered nature of the relational data model. This conflict can be resolved by the following XML-to-Relational mappings: schema mapping, data mapping and query mapping. In this paper, we propose: (i) a lossless schema mapping algorithm to generate a database schema from a DTD, which makes several improvements over existing algorithms, (ii) two linear data mapping algorithms based on DOM and SAX, respectively, to map ordered XML data to relational data. To our best knowledge, there is no published linear schema-based data mapping algorithm for mapping ordered XML data to relational data. Experimental results are presented to show that our algorithms are efficient and scalable. 相似文献
15.
XML has become the standard for publishing and exchanging data on the Web. However, most business data is managed and will
remain to be managed by relational database management systems. As such, there is an increasing need to efficiently and accurately
publish relational data as XML documents for Internet-based applications. One way to publish relational data is to provide
virtual XML documents for relational data via an XML schema which is transformed from the underlying relational database schema
such that users can access the relational database through the XML schema. In this paper, we discuss issues in transforming
a relational database schema into the corresponding XML schema. We aim to preserve all integrity constraints defined in a
relational database schema, to achieve high level of nesting and to avoid introducing data redundancy in the transformed XML
schema. In the paper, we first propose a basic transformation algorithm which introduces no data redundancy, then we improve
the algorithm by exploring further nesting of the transformed XML schema. 相似文献
16.
XN-Store:一种原生XML数据库的存储方案 总被引:1,自引:0,他引:1
随着XML相关标准的推广与应用,Web上出现了大量的XML文档,为了进行有效的管理,有必要将XML文档存储到数据库中,存储方案已成为XML数据管理领域研究的一个重要课题,将XML文档映射为关系表,存储到传统的RDBMS中,会破坏XML数据的树形结构,造成查询效率的下降,提出了一种新的用于原生XML数据库的存储方案--XN-Store,该方案基于索引结构将XML节点作为记录直接存储到分页文件中,建立起持久化文档对象模型,从而保持了XML数据原有的树形结构.XN-Store不仅降低了XML文档的存储空间开销,而且实现了XML节点的快速串行化输出和访问操作.作为通用的原生XML存储方案,XN-Store支持各种二级索引的创建,以提高XML查询处理的效率,采用多种数据集,分别在XN-Store和先前的XML存储系统上进行实验,比较存储空间、存储时间、串行化时间和节点访问时间.实验结果表明,XN-Store是一种高性能的原生XML数据库存储方案. 相似文献
17.
Jayavel Shanmugasundaram Eugene Shekita Rimon Barr Michael Carey Bruce Lindsay Hamid Pirahesh Berthold Reinwald 《The VLDB Journal The International Journal on Very Large Data Bases》2001,10(2-3):133-154
XML is rapidly emerging as a standard for exchanging business data on the World Wide Web. For the foreseeable future, however,
most business data will continue to be stored in relational database systems. Consequently, if XML is to fulfill its potential,
some mechanism is needed to publish relational data as XML documents. Towards that goal, one of the major challenges is finding
a way to efficiently structure and tag data from one or more tables as a hierarchical XML document. Different alternatives
are possible depending on when this processing takes place and how much of it is done inside the relational engine. In this
paper, we characterize and study the performance of these alternatives. Among other things, we explore the use of new scalar
and aggregate functions in SQL for constructing complex XML documents directly in the relational engine. We also explore different
execution plans for generating the content of an XML document. The results of an experimental study show that constructing
XML documents inside the relational engine can have a significant performance benefit. Our results also show the superiority
of having the relational engine use what we call an “outer union plan” to generate the content of an XML document.
Received: 15 October 2000 / Accepted: 15 April 2001 Published online: 28 June 2001 相似文献
18.
在某大型软件系统中,采用XML来表示多种不同格式的文书和其它信息,能够大大简化系统编程接口和加快信息交流共享.XML文档处理子系统是该大型软件系统的重要组成部分,为其他子系统提供高效存储处理各种信息的统一接口.从XML文档映射模式的相关研究开始,在XML文档处理子系统的设计中提出了一种简单高效的XML文档到关系数据库的映射模式,有效提高了系统处理XML文档的速度. 相似文献
19.
We consider data exchange for XML documents: given source and target schemas, a mapping between them, and a document conforming to the source schema, construct a target document and answer target queries in a way that is consistent with the source information. The problem has primarily been studied in the relational context, in which data-exchange systems have also been built. Since many XML documents are stored in relations, it is natural to consider using a relational system for XML data exchange. However, there is a complexity mismatch between query answering in relational and in XML data exchange. This indicates that to make the use of relational systems possible, restrictions have to be imposed on XML schemas and mappings, as well as on XML shredding schemes. We isolate a set of five requirements that must be fulfilled in order to have a faithful representation of the XML data-exchange problem by a relational translation. We then demonstrate that these requirements naturally suggest the in-lining technique for data-exchange tasks. Our key contribution is to provide shredding algorithms for schemas, documents, mappings and queries, and demonstrate that they enable us to correctly perform XML data-exchange tasks using a relational system. 相似文献
20.
一种XML数据库到关系数据库的映射模型 总被引:1,自引:0,他引:1
介绍如何将XML文档转换成标签有向图。讨论基于这种标签图将XML数据库映射成关系数据库。这种映射模式包括两个步骤,即属性映射和值映射。最后讨论在这种映射模式下,针对数据库的几种操作。 相似文献