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daniele_tiles's avatar
daniele_tiles
Icon for Advocate II rankAdvocate II
2 years ago

Difference between "normal" semantic model and default semantic model in a Lakehouse?

Hi to all, we're trying to understand how to move an existing semantic model made on PBI Desktop to a Default Semantic Model on a Lakehouse. We're experiencing some differences in capabilities, and...
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Anonymous's avatar
Anonymous
Not applicable
2 years ago

Hi daniele_tiles ,

 

The inability to create many-to-many relationships in a Default Semantic Model is a known limitation. This stems from the design principles of Power BI and Microsoft Fabric, where the emphasis is on maintaining a star schema for analytical models to ensure optimal performance and simplicity in report design. Many-to-many relationships can introduce complexity and ambiguity in data analysis, which is why they are generally not recommended. However, if you need to model such relationships, consider using bridge tables or creating explicit dimension tables to simulate the many-to-many relationship indirectly. For more insights on handling many-to-many relationships, please refer to this documentation: Many-to-many relationships in Power BI Desktop - Power BI | Microsoft Learn

 

Hope it helps!

 

Best regards,
Community Support Team_ Scott Chang

 

If this post helps then please consider Accept it as the solution to help the other members find it more quickly.

daniele_tiles's avatar
daniele_tiles
Icon for Advocate II rankAdvocate II
2 years ago

Hi Anonymous ,

we had a call with Microsoft Support and I'm a bit baffled from what we've found (and the support will go through this because it's strange).
So, the default semantic model has this problem on many-to-many relationship. However, if we create a new semantic model on Power BI Service on the Lakehouse, it's possible to define the many-to-many relationship.

And the interface is different! So I'm getting even more confused...

Kind regards

 

Daniele

  • daniele_tiles's avatar
    daniele_tiles
    Icon for Advocate II rankAdvocate II
    2 years ago

    Hi Anonymous ,

    we've also checked that with a new PBI Semantic Model, created against the lakehouse via PBI Service, we can rename columns and tables to be more useful for the final users, and the same of the original semantic model. And it's really a semantic model, because it doesn't modify the physical name of columns and tables on the lakehouse.

    So I'm very confused about the differences and limitations (why the default semantic model is so rigid, and why a new semantic model on a Lakehouse is not?).