Pattern tree-based XOLAP rollup operator for XML complex hierarchies

With the rise of XML as a standard for representing business data, XML data warehousing appears as a suitable solution for decision-support applications. In this context, it is necessary to allow OLAP analyses on XML data cubes. Thus, XQuery extensions are needed. To define a formal framework and allow much-needed performance optimizations on analytical queries expressed in XQuery, defining an algebra is desirable. However, XML-OLAP (XOLAP) algebras from the literature still largely rely on the relational model. Hence, we propose in this paper a rollup operator based on a pattern tree in order to handle multidimensional XML data expressed within complex hierarchies

A Survey on Data Integration in Data Warehouse

Data warehousing embraces technology of integrating data from multiple distributed data sources and using that at an in annotated and aggregated form to support business decision-making and enterprise management. Although many techniques have been revisited or newly  developed in the context of data warehouses, such as view maintenance and OLAP, little attention has been paid to data mining techniques for supporting the most important and costly tasks of data integration for data warehouse design