Daniel Hallam (9/19/2012)
Should the dimension have an excessive number of business keys if the source data warrants it?
I would say more if the questions the users were asking of the data warranted it.
Does snowflaking make sense under the circumstances?
What you're discussing really is why snowflaking became more common, but the question really comes down to can they use some of the dimensions without the others for the most common questions asked of the data mart? If yes, then snowflake, if not, don't.
Is creating mini-dimensions and having more keys on fact tables a better choice?
That's going to depend on just how wide that's going to get, honestly. I personally would need more information to make that judgement call, because that's what it comes down to.
Would others merge data at the source and get a full row before getting to staging?
Under most circumstances, this is what I do. Then I use the RowID + Checksums to test for updating, to strip out anything that doesn't need to be modified. For either static dimensions or SCDs you still need to check for change.
You've got a bit of a mess there. The only recommendation I can make to you is start with snowflake and then work into combining the split leaves when the data is un-separatable. For example, if you never really look up particular data without category information as well, combine it. If you often look up by one or the other, leave 'em separate to ease ETL duties, particularly if you have a very low latency requirement.
- Craig Farrell
Never stop learning, even if it hurts. Ego bruises are practically mandatory as you learn unless you've never risked enough to make a mistake. For better assistance in answering your questions | Forum Netiquette
For index/tuning help, follow these directions. |Tally TablesTwitter: @AnyWayDBA