Skip to main content
cancel
Showing results for 
Search instead for 
Did you mean: 

Find everything you need to get certified on Fabric—skills challenges, live sessions, exam prep, role guidance, and more. Get started

Reply
itchyeyeballs
Impactful Individual
Impactful Individual

Datamart report slow

Hi All,

 

I have been playing with the Datamarts feature, has anyone else noticed it's really slow?

 

I've recreated a portion of an existing dataset as a datamart, (reports against the original larger/more complex dataset run fine). My first (basic) report against the Datamart is really slow, just expanding rows in a single matrix table takes ages (380k rows fact table, 4 small dimensions).

 

I'm using the option to connect to the autogenerated dataset rather than the SQL endpoint as I assumed that would give the best performance.

Anyone else find the same? It's a preview feature so some issues expected but I'm a bit disappointed with it at the moment. 

1 ACCEPTED SOLUTION

Hi @itchyeyeballs 

 

yes this is because the datamart using DirectQuery to the underlying database (SQL Server), while the other report uses the Power BI Vertipaq engine which is super fast.





Did I answer your question? Mark my post as a solution!

Proud to be a Super User!







Power BI Blog

View solution in original post

7 REPLIES 7
itchyeyeballs
Impactful Individual
Impactful Individual

Hi all,

MS has released an update to dataflows that appears to indicate better performance, has anyone noticed any improvements? (is there a way to check if the new "auto import" feature is on?)

https://powerbi.microsoft.com/en-us/blog/whats-new-in-datamarts-august-2022/


My tests still seem really slow, if I connect to the datamart it's worst, connecting directly to the datamart dataset is slightly better but still not great and nowhere near as good a stand import dataset.

otravers
Community Champion
Community Champion

Is your existing dataset in Import or DirectQuery mode?

------------------------------------------------
1. How to get your question answered quickly - good questions get good answers!
2. Learning how to fish > being spoon-fed without active thinking.
3. Please accept as a solution posts that resolve your questions.
------------------------------------------------
BI Blog: Datamarts | RLS/OLS | Dev Tools | Languages | Aggregations | XMLA/APIs | Field Parameters | Custom Visuals

Import, direct query has always been way too slow to be useful with our on prem sql server and gateway.

 

This datamart experience feels like it has the same direct query bottleneck

If it has always been slow even when importing I would suggest making sure your dataset is using a star schema. 

 

DirectQuery is as fast as the underlying data source, along with once again a star schema design.





Did I answer your question? Mark my post as a solution!

Proud to be a Super User!







Power BI Blog

Hi, we are using a star schema.

 

As a test I lined up two instances of PBI Desktop, one using the original data model and one using the new datamart (both identical in terms of tables, joins and import modes).  I created identical (simple) matrix visuals and tried to expand the same row in each version of the report.

The original data model has an instant reaction every time, the datamart version shows a spinning loading icon for at least 5 seconds (sometimes more)

Hi @itchyeyeballs 

 

yes this is because the datamart using DirectQuery to the underlying database (SQL Server), while the other report uses the Power BI Vertipaq engine which is super fast.





Did I answer your question? Mark my post as a solution!

Proud to be a Super User!







Power BI Blog

GilbertQ
Super User
Super User

Hi @itchyeyeballs 

 

This is a version 1 of datamarts so it is still a work in progress.


Another thing to note as of today is even with the auto generated dataset it is still querying the underlying SQL Server database. So if there are a lot of rows and columns this will take some time to show all the rows.

 

It should improve over time.





Did I answer your question? Mark my post as a solution!

Proud to be a Super User!







Power BI Blog

Helpful resources

Announcements
Europe Fabric Conference

Europe’s largest Microsoft Fabric Community Conference

Join the community in Stockholm for expert Microsoft Fabric learning including a very exciting keynote from Arun Ulag, Corporate Vice President, Azure Data.

July 2024 Power BI Update

Power BI Monthly Update - July 2024

Check out the July 2024 Power BI update to learn about new features.

July Newsletter

Fabric Community Update - July 2024

Find out what's new and trending in the Fabric Community.