Finding your way through multidimensional data models

Multidimensional database technology is becoming more and more important in conjunction with data warehouses and OLAP analysis. What is still lacking is a commonly accepted formal foundation. Such a model can serve as a basis for future research and standardization. Recently a multitude of interesting proposals on this topic have been published. OLAP applications have some special requirements that do not apply to other areas of multidimensional analysis (e.g. GIS, PACS). We list requirements that a formal model and a corresponding query language must fulfill to be suitable for OLAP. We compare four approaches that come closest to our requirements. After a brief description we discuss their suitability as a formal foundation for OLAP, thus providing a systematic overview. Finally, we propose directions for further research