A Study Of XML Data Based On Query Optimization

The rapid development of Web technology makes Web become an important way of people's accessing. With the sharp increase in the amount of information, how that diversification of the Web and exchange data become key issues. Following HTML (HyperText Markup Language), XML (extensible Markup Language) has become the principal that the Internet and information exchange tools.Different with HTML, XML documents realized the data content and expression of separation, thus benefiting the information sharing and retrieval, but also the non-structural XML documents for the organization, management and retrieval was extremely difficult. XML documents so different from the characteristics of object relations and the traditional structure of the data and semi-structured data into a unique data, how to efficiently obtain useful XML data and to optimize XML Query as a new study.In order to achieve the XML data query optimization, in recent years people have made a lot of indexing technology and connectivity algorithms, these indexes are based mainly on edge labels and elemental duty to establish. But some index does not contain all the elements of nodes, thus carrying out inquiries, many paths still need testing; Some traverse forward or backward generated a lot of redundant data, resulting in greater price inquiries.In this paper, XML data inquiries launched research, query language, data model, query optimization based on the Index has done the following aspects:(1) This paper focus on the needs of Schema XML Query Language Mode done a study, based on this algorithm generally made inquiries bottlenecks.(2) In view of existing database products in the management of the advantages of XML data against data in XML Commissioner Storage of data in the form of XML data and relationships between the fixed table mapping model was studied, and the achievement of three different size storage model.(3) Based on the common path expression Schema (GPE) into a simple path expression (SPE) a new method G2S, the XML query optimization is an important step. G2S is a heuristic approach, which uses the XML Schema statistical information to rewrite GPE for SPE. (4) The proposed use of Schema generation models, and based on this proposed based on the XML Schema Index data structure, the data dictionary with Schema raised OB (Orthogonal B + tree) tree storage methods can be quickly establish the relationship between elements, and reduce the element of the road visit Drive link frequency, thus shortening the path query response time and improve the efficiency of the inquiry, with extraordinary practical significance.