How to add a column to the “after” fact table, is it already expanded and populated?

Question

I have a Data-Mart SQL Server 2005 star schema with regular fact and dimension tables. This is deployed and populated through an SSIS-based ETL package. So far so good.

I just turned to a customer with a new requirement. Never hear you speak! This requirement will mean that I need to add a new dimension table in data-mart to measure a new aspect of the incoming facts that turn out to be financial.

To “crop” facts from this new dimension, I need to add a new foreign key column to the fact table linking the new dimension.

I don’t understand how to do this. What to do with data that has already been captured? Just invalidate the new column and accept that the old fact will be NULL? In fact, when I print, it became clear to me that I can update the old facts. Or maybe I should create a separate (child?) Fact table, which will simply contain a link to each new (parent) fact and a link to a new dimension.

I could not find any best practice information for this type of change.

Any help would be greatly appreciated.

By the way. Analysis Services has not yet been used.

Thanks Martin

Answer 1

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