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Query Processing using Dynamic Relational Structure for Semistructured Data


B.M. Monjurul Alom, Frans Henskens, Michael Hannaford


Vol. 10  No. 4  pp. 104-113


The most promising and dominant data format for data processing and representation on the Internet is the semistructured data form termed XML. XML data has no fixed schema; it evolved and is self describing which results in management difficulties compared to, for example, relational data. It is therefore a major challenge for the database community to design query processing techniques and storage methods that can retrieve semistructured data efficiently. In this paper, we present a querying scheme for semistructured data views of relational form. The proposed technique stores element-paths, attributes, contents of the element paths and attributes, and XML processing instructions in a dynamic relational structure termed as Multi-XML-Data-Structure (MXDS). The technique supports different kinds of queries (such as structural-join, general path query, and twig query) and the existence of attributes in the XML documents. We use a secondary index on MXDS to reduce the search time. The indexing is based on the (assigned) elementary-code value (not encoded value). The proposed technique also supports dynamic data manipulation. Experimental results show the twig query execution time of our proposed technique outperform than that of some other XML query processing techniques (such as TwigStack, TwigStacklist). We performed experiments for relational query using MySQL and ORACLE. To compare with the XML query processing time we also measured query execution time using the XQuery language. We then we analysed the query performance between XML and relational queries.


TwigStack, Structural Join, XPath, XQuery, MySQL, Oracle