When using DAX in a semantic model will Fabric fall back to Direct Query

[DShallcross]

We have a semantic model created and inside we have a main date table. We wanted to create other tables based on this date table, whilst still using DirectLake for performance. Initially we tried creating views but realised that views fall back to DirectQuery mode when trying to use them in a filter. So I wondered if alternatively we could use DAX instead? Reading through the documentation here Direct Lake overview - Microsoft Fabric | Microsoft Learn it mentions "Import and Direct Lake storage modes use the VertiPaq engine to process DAX queries and return results to the Power BI report and user" so I presume that mean it won't fall back to DirectQuery mode but I wanted to check before I start the laborious process of changing them all to DAX

[tayloramy]

Hi @DShallcross 

When using DirectLake models, the views should be calculated and materialized as tables on the lakehouse/warehouse before getting to the semantic model. 

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[DShallcross]

We created the views in the warehouse first and then added those views into the semantic model. During the creation of a PowerBI report when trying to add a filter using those views it mentions that it will fall back to DirectQuery mode.

[tayloramy · Accepted solution]

Hi @DShallcross, 

Yes, this is why they should be materialized and stored as tables for DirectLake on warehouses. On Lakehouses, materialized lake views work in directlake mode for semantic models. 

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[DShallcross]

Thank you, I believe this is what I will need to do and materialize my views as tables.

[Cookistador]

Hi @DShallcross 

In your case, you can only create a calculated table using direct lake if calculations is not referering to columns of tables in Direct Lake mode.

(source: https://learn.microsoft.com/en-us/fabric/fundamentals/direct-lake-overview#fabric-item-permissions)

So in your case, you will have to create view directly in your lakehouse/warehouse

But of course, you can create measure

[DShallcross]

Unfortunately if we create views it falls back to DirectQuery mode so that is off the table for us. If DAX is also not possible in DirectLake then we will have to create extra tables