Friday, September 24, 2010

how about the rapidly changing dimension (RCD)?

If, on average, the rows in the dimension tables change once a month or more frequently, how do we store the historical value of dimensional attributes? The answer is that we store them in the fact table. Say we have a customer dimension with ten attributes. Attributes 1 to 9 change once a year. Attribute 10 changes every day. We should remove the 10th column from the customer dimension and put it as a degenerate dimension column in the fact table


A degenerate dimension doesn’t have a dimension key

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