Dso Key feilds

Hello Everybody

I am desigining a dso and the question is can i have the keys figured out for dso without looking at the data and the primary tables in R/3/Ecc keys. Somebody was telling me that look at the requirements or the cube its feeding that will give me the idea. I am not sure about that. Besides i am pulling all the feilds from a standard data source as it is and then feed it to a cube all of it.

Thanks