Tuesday, October 13, 2020

Degenerated Dimension

In some dimension, we may find that we don't have any dimension attributes but only its business key. Transaction Number is an example, other transaction header's attributes are logically organized in other dimensions. (e.g. Transaction date is organized to Date dimension) It doesn't make sense to create a tiny dimension with just the surrogate key and business key. So, we may consider to degenerate the dimension and store the business key (e.g. transaction number) in the fact table. Size and the content nature would be the way of our consideration (e.g. we degenerate the invoice number but not the invoice remarks). We call such a degenerated field in the fact table as the degenerated dimension.

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