Forum Discussion
Helper VFabric - semantic model performance
Community ChampionYou can use the Direct Lake Only setting to verify that your queries are indeed Direct Lake:
(You can also open the report in Power BI Desktop, and use Performance Analyzer to see if DirectQuery is being used. Or run queries in DAX studio to verify the same.)
Be sure to use a custom (new) direct lake semantic model. Don't use the default direct lake semantic model.
Helper Vthank you
I have a follow up questions
1)
looking at one of my tables in the semantic model
the table is sourced from a view in the warehouse (as I understand direct lake is not supported for views. But why do the property (storage mode) say "Direct Lake"?
2)
if I have a model with a mix of direct lake (tables) and direct query (views)
will queries that only consumes direct lake objects use direct lake or is it all or nothing for a semantic model?
- frithjof_v
1) I don't know, perhaps a bug in the user interface?
2) I believe only visuals which use the View will fall back to DirectQuery. Other visuals should be unaffected and keep using Direct Lake.
This can be tested, if you turn on "Direct Lake Only", then you will see the DirectQuery visuals failing.
Or you can open the reports in Power BI Desktop, and use performance analyzer to check for a DirectQuery activity.
If some visuals fall back to DirectQuery, then that is probably the biggest performance issue.
Here I am using Performance analyzer in Power BI desktop to query a table and also a similar view. The view causes a fallback to DirectQuery.
- joakimfenno
thanks, I get results like below even thought all tables accessed by the query are tables
- frithjof_v
Perhaps the query is just too big, then it falls back to DirectQuery.
Did you enable SQL granular permissions on any of the tables? In that case, it may fall back to DirectQuery.
Did you try using the "Direct Lake Only" setting?
Hi joakimfenno ,
frithjof_v answered the other questions very well, I only have one small point to add.
Direct Lake mode, based on loading parquet format files directly from a data lake, is a semantic modeling feature used to analyze very large data volumes in Power BI.
While Direct Lake can be used with views, queries to view-based model tables will always fall back to Direct Query mode, which can lead to reduced query performance. This is why the Storage Mode property is displayed as “Direct Lake”.
Develop Direct Lake semantic models - Microsoft Fabric | Microsoft Learn
Best Regards,
Yang
Community Support TeamIf there is any post helps, then please consider Accept it as the solution to help the other members find it more quickly.
If I misunderstand your needs or you still have problems on it, please feel free to let us know. Thanks a lot!