Load all the data from your data base(Table or View) and store it into qvd files.DO NOT CHANGE THE DATA STRUCTURE IN THIS TIER
Second Tier
Load the qvd file that you stored in Tier1 and write your calculate logic(where clause\sum group by and etc.).After you finish your code,store your calculate result into several new qvd files,such as SalesData.qvd\Supplychain.qvd and etc.
Third tier
Use the qvd files that you stored in Tier2 to build your data model
