Adventure works databases

I am new to Analysis Services.

In the adventureworks sample, we have the oltp database (AdventureWorks), the datawarehouse (AdventureWorksDW) and the cube (Adventure Works DW). I am a little lost here. I thought the SSIS package updated the cube directly from the OLTP database.

Looks like the datawarehouse is used to convert the OLTP to a star schema and *then* the cube is loaded.

Could you please explain.

Thanks!

The datawarehouse (DW) is an OLAP multidimensional database that uses data from the OLTP relational database to create cubes, dimensions and so on. Whether the data in cubes is being updated automatically from the OLTP database depends on the settings, specifically the storage type of partition aggregations (MOLAP, ROLAP, HOLAP and variations). Those that are used in Adventure Works by default use MOLAP, which is great for analytical processing, reports and so on. Here is some more information on that: http://msdn2.microsoft.com/en-us/library/ms178416.aspx .