Building a cube vs DW?

[actcognosuser]

Hi All,
             I have a question about building cubes.For cognos there is transformer to build cubes.Can we build a cube directly from database.(like Oracle or db2?).

Or do we actually need to go through the tool provided by the vendor?

Cubes can be built off a DW.But what is d difference betwn a DW and a cube.Can it be an option to use a cube instead of a DW?

[MFGF]

Cubes are typically summarized, whereas a data warehouse is usually expected to support a more detailed level of data.  Warehouses usually also preserve history, and span the entire Enterprise whereas cubes can be more focused.

[actcognosuser]

Thanks for ur response MFGF. If I need to build a cube do i have to go with any of the vendor specific tools
or is it possible to build one directly from a database.

also is a dw metadata or does it contain  actual data like the cube?

[MFGF]

Use the appropriate cube building tool to create the desired cube.  For example, you will need Transformer in order to create a PowerCube.

I assume that when you refer to a data warehouse, you are thinking of the Presentation Layer, where the reporting data is stored in a form that is fast and easy to report from.  It is usually just a collection of interconnected database tables and/or views, often in the form of star schemas, but it does contain the actual reporting data.

MF.

[actcognosuser]

is cube a concept or is it tool specific???

[cognostechie]

A Cube is a physical object that contains data inside it in a multi-dimensional form. In case of Cognos Poercube , it is an ascii file that contains data inside it. In case of other cubes like SAP BI, it is a collection of tables inside a database which again stores data inside it. Yes, it is tool specific.

I would suggest browse the internet to get the basic idea about what is a cube and what is a DW. There are some databases that have their own cube building tools.