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itchyeyeballs's avatar
itchyeyeballs
Impactful Individual
4 years ago
Solved

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. 

Need Help
  • GilbertQ's avatar
    GilbertQ
    4 years ago

    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.

7 Replies

  • GilbertQ's avatar
    GilbertQ
    Super User
    4 years ago

    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.

  • otravers's avatar
    otravers
    Community Champion
    4 years ago

    Is your existing dataset in Import or DirectQuery mode?

    • itchyeyeballs's avatar
      itchyeyeballs
      Impactful Individual
      4 years ago

      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

      • GilbertQ's avatar
        GilbertQ
        Super User
        4 years ago

        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.

  • itchyeyeballs's avatar
    itchyeyeballs
    Impactful Individual
    4 years ago

    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.