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Pawel_1990's avatar
Pawel_1990
Helper I
1 year ago
Solved

SnowFlake - Direct Query - Slow Perfomrance - Adding Role at Power Query

Hello, I am using Snowflake as source for reports. Some of reports were not changed for over a 1,5 year.  Company made decision, that due to security reasons, some data will be masked and roles w...
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  • Shahid12523's avatar
    Shahid12523
    1 year ago

    Why it's slow now
    - Adding roles and masking in Snowflake forces full table scans—even unused columns get queried.
    - Power BI now unmasks first, filters later, which breaks query folding and slows things down.

    ✅ What to check
    On Snowflake side:
    - Use column-level masking, not table-level.
    - Add clustering keys and materialized views.
    - Ensure warehouse is right-sized and optimized.
    On Power BI side:
    - Maximize query folding in Power Query.
    - Use composite models (import + DirectQuery).
    - Reduce visuals, optimize DAX, enable Horizontal Fusion.

Anonymous's avatar
Anonymous
Not applicable
11 months ago

Hi Pawel_1990 ,

Thanks Shahid12523 , that’s a really solid breakdown.
My earlier note was more about handling this at the design layer (using reporting views so the masking doesn’t force table scans every time). Your tips on column-level masking, clustering/materialized views, and Power BI folding/composite models add great performance-tuning angles.

Between both approaches, Pawel_1990  has options either redesign with views if possible, or optimize Snowflake/Power BI settings to mitigate the impact.

Regards,
Akhil.