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How to Model a Data Warehouse? Reporting team May 16, 2004 Wayne Lee Data Warehouse Architecture • • • • • Data is represented by a Star (InfoCube) Organized to provide good performance Flexible to organizational change Information is provided on aggregated level Generally NO transaction reporting BW Star Schema Master Data (Attributes describing a characteristic) Dimension Characteristics (By What are Key Figures viewed) Dimension Characteristics (By What are Key Figures viewed) Master Data (Attributes describing a characteristic) Key Figures (Everything what can be counted) Master Data (Attributes describing a characteristic) Dimension Characteristics (By What are Key Figures viewed) Dimension Characteristics (By What are Key Figures viewed) InfoCube Master Data (Attributes describing a characteristic) How To Decide Where To Place Data Elements ? • Fact Table (Key Figures) – All objects to be counted – All values to be calculated • Dimensions (Characteristics) – All organizational objects required to preserve the historical truth – All objects by which Key Figures are to be viewed (Slice & Dice) • Master Data (Attributes) – All object describing a characteristics – Generally only for display (informational) – Exceptional Drill-Down (Navigational Attributes) Additional Considerations • Historical Truth vs. Flexibility to Change – Yesterday or Today • A past result can be reproduced – Yesterday is Today • A past result is viewed with current organization (characteristics) – Today is Yesterday • Today’s results is viewed with past organization (characteristics) – A combination of the above • Object must reside in both Dimension and Master Data Performance Master Data (Attributes describing a characteristic) Dimension Characteristics (By What are Key Figures viewed) Dimension Characteristics (By What are Key Figures viewed) Master Data (Attributes describing a characteristic) Key Figures (Everything what can be counted) Master Data (Attributes describing a characteristic) Dimension Characteristics (By What are Key Figures viewed) Dimension Characteristics (By What are Key Figures viewed) Master Data (Attributes describing a characteristic) InfoCube Good Performance Less Performance