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Jeanxyz's avatar
Jeanxyz
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9 months ago
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degenerate dimensions

I'm reading MS documentation about data modeling, and got confused about degenerate dimensions. Basically MS says if there is only one column in the dimension table and this column (e.g., sales order...
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  • v-achippa's avatar
    v-achippa
    9 months ago

    Hi Jeanxyz,

     

    Yes you are right that one column does not automatically mean 1:1. The real rule is that,
    If that column has repeated values and is used to group or filter across many fact rows, then it is a real dimension and should stay as a dimension.
    If the column is almost unique for each fact row and has no descriptive attributes or reuse, then it behaves like a degenerate dimension and there is no benefit in keeping a separate table.

     

    So the decision is not based on the number of columns, it is based on cardinality and whether the column actually functions as a dimension.

     

    Thanks and regards,

    Anjan Kumar Chippa

v-achippa's avatar
v-achippa
Icon for Community Support rankCommunity Support
9 months ago

Hi Jeanxyz,

 

Yes you are right that one column does not automatically mean 1:1. The real rule is that,
If that column has repeated values and is used to group or filter across many fact rows, then it is a real dimension and should stay as a dimension.
If the column is almost unique for each fact row and has no descriptive attributes or reuse, then it behaves like a degenerate dimension and there is no benefit in keeping a separate table.

 

So the decision is not based on the number of columns, it is based on cardinality and whether the column actually functions as a dimension.

 

Thanks and regards,

Anjan Kumar Chippa

v-achippa's avatar
v-achippa
Icon for Community Support rankCommunity Support
9 months ago

Hi Jeanxyz,

 

As we haven’t heard back from you, we wanted to kindly follow up to check if the solution I have provided for the issue worked? or let us know if you need any further assistance.

 

Thanks and regards,

Anjan Kumar Chippa

  • v-achippa's avatar
    v-achippa
    Icon for Community Support rankCommunity Support
    9 months ago

    Hi @Jeanxyz,

     

    We wanted to kindly follow up to check if the solution I have provided for the issue worked? or let us know if you need any further assistance.

     

    Thanks and regards,

    Anjan Kumar Chippa