BASICS: VDDW Architecture   >   Common Star Schemas

• Enlarge VDDW Architecture VDDW Components: Overview Common Dimensions Common Schemas ABC Allocation Activity Dimension Contribution & Consumption OLAP HyperCube What's Left Out

  The VDDW relies upon a typical collection of star schemas as the primary driver inputs to the ABC allocation engine. 

• What is a star schema?  A star schema consists of a "fact" table that connects various "facts" or "measures" to those dimensions by which it is relevant to analyze them. As an example, the Sales star schema, depicted above, captures Sales $, COGS, and quantity sold (the "facts") at the intersection of various customers, products, time periods, and locations.  In a star schema, the fact table data is typically sourced from operational transactions which define the "grain" of the table (e.g., invoice line items, or inventory movements). That is to say, a single record in the Sales fact table would correspond to a single invoice line item.

• The "facts" supplied by the various DW star schemas become the primary driver inputs to the ABC allocation engine.  What does this mean? The ABC allocation engine requires "drivers" to determine how to apportion expenses. A "driver" is a variable or numeric measure which the ABC engine uses as a weighting factor to determine how efficient one transaction is relative to others, and therefore, how much activity expense it should receive. Example: Freight expenses might by allocated by the physical weight of a given product multiplied by the total quantity of the product shipped, reflective of how these two drivers (product weight and quantity) sensibly apportion the expense of shipping a truckload of product.  The best sources of driver data are individual fact table records because an atomic business transaction, which is what a fact table record represents, also represents the culmination of a single iteration of business activities, and the transaction is where the most useful data comes together for allocation purposes.

• The star schemas employed in a conventional data warehouse supply both the driver inputs to the ABC allocation engine, and therefore also the correlating explanation behind why the allocated dollars coming out the other side of the engine are what they are.

• 
  
•  

• Learn More: Information Supply Chain Basics How VDDW Streamlines the ISC VDDW and Corporate Performance Management How VDDW Delivers Results VDDW Distinctives