Efficient simple path and Twig query processing algorithms for XML data organized as multidimensional file

XML has emerged as a new standard for information representation and exchange on the Internet. Nowadays, the number of applications using XML data is increasing rapidly. As a result, it is important to develop efficient algorithms to query XML data. XML documents have nested structure. Thus, querying XML documents require values search and structure search. Evaluating structural relationship between XML elements is a core operation for XML query processing. Thus efficient support for structural relationship is the key to efficient implementations of XML queries.;In this work, new XML storage system is proposed to support the structural relationship among XML elements efficiently. The proposed XML storage system stores XML data as simple paths by using multidimensional space structure.;Based on this storage system, we proposed two XML query processing algorithms namely Path_MD and Twig_MD algorithms. Path_MD uses multidimensional space structure to answer simple path queries efficiently without involving structural join operations. Twig_MD algorithm is proposed to process twig queries. Twig_MD algorithm reduces the number of joins by processing twig queries as joins of simple path queries.;The proposed algorithms are implemented and tested against holistic query processing algorithms, which are among the best XML join-based query processing algorithms. The experimental results showed that our proposed algorithm outperform Holistic query processing algorithms in terms of number of disk accesses and CPU time needed to answer a query.