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The Data Warehouse Toolkit - Third Edition
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The following section describes the fundamental approaches for dealing with slowly changing dimension (SCD) attributes. It is quite common to have attributes in the same dimension table that are handled with different change tracking techniques.
With type 0, the dimension attribute value never changes, so facts are always grouped by this original value. Type 0 is appropriate for any attribute labeled “original,” such as a customer’s original credit score or a durable identifier. It also applies to most attributes in a date dimension.
With type 1, the old attribute value in the dimension row is overwritten with the new value; type 1 attributes always reflects the most recent assignment, and therefore this technique destroys history. Although this approach is easy to implement and does not create additional dimension rows, you must be careful...
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