Forum Discussion

rdg515's avatar
rdg515
Resolver I
6 years ago

Data Flows - How to limit data in Power BI Desktop

I have a large data set that I intend to create as a Data Flow.  I am frequently adding fields to the data set, and would like to be able to work with this data set in Power BI without having to down...
rdg515's avatar
rdg515
Resolver I
6 years ago

Sorry, I want to make sure I fully undestand because you didn't address my question concerning performance.  It's my assumption that direct query is always slower than imports.  Is this a correct assumption, even with Direct Query against Data Flows in the Service?

 

If that's a correct assumption, and I find that the performance is too slow, what are my options?

1) Create summarized queries (same recourse when working with Direct Query in general)

2) Not use Data Flows because it would just be duplicating data

lbendlin's avatar
lbendlin
Super User
6 years ago

" It's my assumption that direct query is always slower than imports. "

 

That's too ambiguous.  You need to differentiate between developer performance and end user performance.  What is your goal?  Do you want to minimize dataset refresh times or do you want to minimize UI response times?

  • rdg515's avatar
    rdg515
    Resolver I
    6 years ago

    Minimize UI response time / DAX calculation time is the primary concern because of all the data and complexity of the model.

    • lbendlin's avatar
      lbendlin
      Super User
      6 years ago

      Then you need to either go with the wasteful option, or look into a hybrid scenario with aggregations that cover the inital UX  (initial visual renders).  And of course you will want to examine all your measures with DAX Studio.