Data Modeling Help Needed

[dallass]

Hi All,

I am needing some help with enhancing the speed of my dashboard.  I've set refresh rates, caching etc. that I have found in other forums, but the response time is still very slow.  I have 35 tables with hundreds of columns and I am using direct query via Google Bigquery and SQL to pull from 2 different data sources.  I am pulling large data sets with Purchase order information and retail information down to the store level by week.  If I could get someone to guide me via teams or zoom, that'd be ideal as there are probably multiple options to enhance based on the data structure. 

Thanks all!

[v-prasare]

We would like to follow up to see if the solution provided by the super user resolved your issue. Please let us know if you need any further assistance. If your query got resolved we will go ahead and close the thread

Thanks,

Prashanth Are

MS Fabric community support

[v-prasare]

Hi @dallass,

We would like to follow up to see if the solution provided by the super user resolved your issue. Please let us know if you need any further assistance.

Thanks,

Prashanth Are

MS Fabric community support

[v-prasare]

Hi @dallass,

We would like to follow up to see if the solution provided by the super user resolved your issue. Please let us know if you need any further assistance.

@burakkaragoz & @FBergamaschi , thanks for your prompt response.

Thanks,

Prashanth Are

MS Fabric community support

If our super user response resolved your issue, please mark it as "Accept as solution" this helps other user find similar answers quickly

[burakkaragoz · Accepted solution]

Hi @dallass ,

You're dealing with a perfect storm for slow performance - 35 tables, cross-source DirectQuery, and BigQuery. No wonder it's crawling.

The brutal truth: DirectQuery with BigQuery is often a nightmare. BigQuery is designed for big analytical queries, not the hundreds of tiny queries Power BI fires off. Plus, mixing BigQuery and SQL Server means Power BI can't push anything down to the source - it's doing all the heavy lifting locally.

What's probably happening: Every time someone clicks a slicer, Power BI is generating separate queries to both sources, pulling data back, then trying to merge it. That's why your caching isn't helping much.

Real fixes:

Split the **bleep** thing - Separate reports for BigQuery vs SQL data. Stop trying to make them play nice together in one model.

Import what you can - Weekly retail data? That's probably small enough to import instead of DirectQuery. Save DirectQuery for the massive transactional stuff.

Pre-aggregate in BigQuery - Create summary tables for your common views (store/week rollups). BigQuery loves big scans, hates small lookups.

Kill unused columns - Those "hundreds of columns" are slowing every query even if you're not using them.

The webcall thing makes sense - this kind of mess usually needs someone to look at the actual model and say "why the hell are you doing it that way?"

What's your biggest pain point - the initial load time or when users interact with filters?

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[dallass]

This is great info.  I think I need to rebuild the model based on what you've said.  I intially was just trying to see if I could get the data models to connect and visualize the 2 data sources in 1 visual.  I will work on the recommendations and see how that helps with performance.  Thank you so much!

[FBergamaschi]

I cannot guide you via webcall but just to inform you that DirectQuery is inerently slow. The best thing to do is optimizing the data source, as the perfomrance depends on it.

Are the data sources start schema databases? That is very important for performance

Are the data sources dedicated to BI (DWH) or they have to serve ERPs? DWH would perform better

Of course it also depends on your DAX as that needss to be translated into SQL, so please stay away from complex DAX and try to keep it optimized

These are just first things to check, if you want I can give yousome hints on how to keep DAX optmized

If this helped, please consider giving kudos and mark as a solution

@me in replies or I'll lose your thread

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Francesco Bergamaschi

MBA, M.Eng, M.Econ, Professor of BI