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could you please explain what exactly is a degenerating dimension?
Friday, April 14 2017, 02:17 PM
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    Monday, April 17 2017, 03:24 PM - #Permalink
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    First aspect to appreciate is that a Degenerate Dimension is not the same as a Single Attribute Dimension which can have list of values that further describe the the transaction e.g. Claim Type with values of Open, Closed, Paid.

    The value persisted is the identifier of a specific transaction e.g. Purchase Order Number, as the transaction identifier must be unique for each and every fact record.

    There is no grouping of facts feasible via a dimension holding all the PO numbers, so why bother having a dimension with a unique Surrogate Key for each PO Number if the PO Number itself is unique on the Fact table. The Transaction ID e.g. PO Number, may as well be created as a field on the Fact table and the value persisted there.

    Avoids having a Dimension with a record for every record in the Fact i.e. every Dimension to Fact with 1:1 cardinality is effectively a candidate to be a degenerate dimension.
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