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Center for Advanced Calculations (NDCAC)
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Research Overview
On-Line Analytical Processing (OLAP) enables analysts to gain insight about data through fast and interactive access to a variety of possible views on information, organized in a dimensional model. The demand for data integration is rapidly becoming larger as more and more information sources appear in modern enterprises. In the data warehousing approach, selected information is extracted in advance and stored in a repository, yielding good query performance. However, in many situations a logical (rather than physical) integration of data is preferable. Previous web-based data integration efforts have focused almost exclusively on the logical level of data models, creating a need for techniques focused on the conceptual level. Also, previous integration techniques for web-based data have not addressed the special needs of OLAP tools such as handling dimensions with hierarchies. Extensible Markup Language (XML) is fast becoming the new standard for data representation and exchange on the World Wide Web. The rapid emergence of XML data on the web, e.g., business-to-business (B2B) e-commerce, is making it necessary for OLAP and other data analysis tools to handle XML data as well as traditional data formats. Regnecentralen is doing research in the area of OLAP and heterogenious, autonomous data sources.

A prerequisite for using OLAP tools is that structures in the database are expressed in the multidimensional paradigm. Defining the structural aspects of a multidimensional database is an expert task, demanding knowledge of logical database design techniques. Motivated by the increasing use of OLAP tools for analyzing business data and because existing OLAP design methods are not suited for non-professionals (i.e. it demands knowledge of logical design techniques for multidimensional databases), Regnecentralen is doing research within the area of providing automatic approaches for discovering multidimensional structure from general purpose relational databases, thereby greatly easing the process of designing a multidimensional database. In this way, defining multidimensional structure and performing OLAP analysis can easily be accomplished by non-database experts as well as experts. The contribution of Regnecentralen's research is to provide the theoretical background for enabling the automatic derivation of multidimensional schemas from relational databases. This is achieved by developing practical methods and techniques for automatically deriving multidimensional schemas from relational databases, taking special OLAP modeling patterns into account.

Research Accessibility
As much of Regnecentralen's research is done in cooperation with commercial institutions access to research results is limited. However, many general research results has been published and can be downloaded from the publications section. For further information please contact the research department using the contact form in the contact section.

Most Downloaded Publications
Specifying OLAP Cubes On XML Data, Journal Edition (PDF)
Converting XML Data to UML Diagrams for Conceptual Data Integration (PDF)
Discovering Multidimensional Structure in Relational Data (PDF)

External References
DBLP Computer Science Bibliography
The OLAP Council
Datawarehouse Tools and Tutorials
DP Research Unit, Aalborg University
Scientific and Statistical Database Management (SSDBM)

External References Free Math Software
R Project

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