Multidimensional Data Analysis Based on Links

Abstract

Analytical processing (OLAP) tools typically only deal with relational data. Hence, the analytical processing systems on XML data do not have all the functionality provided by OLAP tools to traditional data (i.e. relational). In addition, current commercial and academic OLAP tools do not process XML data that contains XLink. Therefore, there is a need to develop a solution for OLAP systems in order to assist in the strategic analysis of the organizational data represented in XML format. Aiming at overcoming this issue, this chapter proposes an analytical system composed by LMDQL (Link-Based Multidimensional Query Language), an analytical query language; XLDM (XLink Data Metamodel), a metamodel given to model cubes of XML documents with XLink and to deal with syntactic, semantic, and structural heterogeneities commonly found in XML documents; and XLPath (XLink Path Language), a navigation language for XML documents connected by XLink. As current W3C query languages for navigating in XML documents do not support XLink, XLPath is discussed in this chapter to provide features for the LMDQL query processing and a prototype system enabling OLAP queries over XML documents linked by XLink and XML schema. This prototype includes a driver, named sql2xquery, which performs the mapping of SQL queries into XQuery in a relational OLAP server. In order to validate the proposed system, a case study and its performance evaluation are presented to analyze the impact of analytical processing over XML/XLink documents.