Research Of Twig Query Technology In XQuery Engine

As the internet technology has developed rapidly, XML(Extensible Markup Language) has gradually been the factual standard of data exchange and expression in the internet environment. How to use XML efficiently and achieve the query of XML data has been an important subject of internet development.In order to standardize the query and processing of XML data, W3C(World Wide Web Consortium) puts forward to XQuery as an XML query language, and makes it as the recommendation. XQuery is a powerful data query language, which suits the query of various types of XML data sources. It can choose and extract data from XML documents, and reconstruct the query results into new XML documents that the user required. XQuery possesses the ability of querying data, organizing data and describing algorithm, the application of which has been more widely used. The implementation and application of technology of XQuery has gradually been an important research direction.Semi-structure characterizes the XML document. In the query request expressed in XQuery, a large number of tasks aim at the structure of XML data to query. According to the tree structure of XML documents, the Twig Query techniques obtain the query results by using pattern matching method. At present, Twig Query for XML query algorithm has become a prevalent issue, and some XML query algorithms have been proposed, such as TwigStack, Twig2Stack, TwigList and so on. In order to extend the pattern of Twig Query and enhance the expression ability of the tree pattern, a more powerful form of twig queries, namely, Generalized Tree Pattern (GTP), is required.This article aims at the researching of implementation techniques of the XQuery language, and extends the Twig Query ability for the XQuery engine. In this study, the GTP Query is used to replace the traditional Twig Query, and improves the TwigList query algorithm based on the need to weak binding and group enumeration. Meanwhile, the Twig Query will be put into use in the query plan framework. The XQuery query plan description language called FXQL will be extended in order to describe the Twig Query function. And a dedicated Twig Query module will be designed and implemented for the XQuery engine.Through the functional and performance test of the Twig query model, it shows that the extended XQuery execution engine can efficiently support the implementation of Twig Query, and the performance outperforms the former engine.