Research Of Propagating And Keeping XML Functional Dependency

XML has quickly become the standard of information public and exchanging with its advantage of cross-platform,powerful ability to exchange data and the ability of simple,open,expanded since it was created.With rapid development of Internet and its openness,especially the large amount of XML data,Managing and operating XML data effectively has been required.Meanwhile,how to exchange the semantic of XML data web in different environment between kinds of database without lossless is proposed,and quickly become an important problem in theoretical studies.For XML data,it is a recognized problem that the kind of data is grammatical, but lack of semantic information.To solve this problem,researchers have put forward many kinds of semantic constraints.Although XML as a data exchange has been used as the major formats and standards in practical application,in order to effectively use the relational database to manage XML data,and to use the applications based on relational database system,usually need to storage XML in local relational database. Semantic constraints in XML data is proposed,and how to map these semantic constraints information to relation databases is an important research topic.It is regarded as a higher theoretical value and practical significance.In this paper,several aspects of the issues related to the problem are studied.The main novelty and contributions can be summarized as follows:The basic theory and application of XML system is introduced the especially the practical advantages of exchanging information on the Internet.After comparing relational model schema and XML model,the disadvantage of looseness of semantic constraints of XML is studied,and as the main research of this paper.Introduced the semantic constraints on XML and function dependency,and compare two kinds of XML model DTD and XML Schema,such as their advantage and disadvantage.And then the DTD of XML is chosen as the basis of research of this Propose the system of XML functional dependency,and the formal definition is given on XML DTD.Then the DTD graphic and the algorithm of how to construct this kind of graphic is given to study well.By studying the function dependency contains of XML,the minimized cover and its algorithm is given,with the guarantee that the semantic constraints are kept well.Based on the previous study,we present the design and implementation of the algorithm of DiscoverXFD,for efficient discovery of XML Data redundancies and some other algorithms.They employ a novel XML data structure and introduce a new class of partition based algorithms.DiscoverXFD can not only be used for the previous definitions of XML functional dependencies,but also for a more comprehensive notion we develop in this paper,capable of detecting redundancies involving set elements while maintaining clear semantics.Experimental evaluations using real life datasets demonstrate that our algorithms is practical and scales well with increasing data size.