XQuery Query Processor Design And Implementation

With the development of computer technology and network data surge and the format ofdata has become increasingly complex, the applications base on XML data become more andmore. There are two main stages to support XML data. One is XML-enabled database and theother is native XML database which is specially design for XML data. Both methods havetheir advantages and disadvantages, the former is on the expansion of the traditional relationaldatabase to support for XML data, while the latter is specially designed database using thefeatures of XML data. In general, native XML database for XML data processing will bemore direct and efficient higher. But the native XML database there are still many problems,it is not like a traditional relational database has a complete set of query optimization methods.Therefore, for the native XML database, we need to study its query optimization method toenhance the efficiency of its query.In this paper, we introduce the XML-related technologies, including existing XML querymethods, optimization methods and the two main forms of XML query language XQuery andXPath and other aspects of technology. By analyzing the results of existing technologies andquery language features, we proposed an XQuery query processor design and the design hasbeen implemented.For an XQuery query, firstly, by using the converting algorithm to extract the query bodyin the original XQuery query, converted it into one or more XPath query, then use these XPathqueries for equivalence queries and obtain query results. Normally, query statements in anative XML database query, it will first get a query plan, we studied the XPath optimizationrelated technologies, presents a cost-based estimating approach, through a dynamicprogramming algorithm makes the query plan is optimized to improve the efficiency of query.In order to accomplish this optimization method, we used a hierarchical coding and statisticalinformation of nodes relevant technology. Through related experiments, analyze experimentalresults, the results show that our XQuery query processor can effectively improve theefficiency of an XQuery query statement.