Forum Discussion

gitgithan's avatar
gitgithan
Frequent Visitor
2 years ago

How does filtering dimension table after merging with fact table affect the merged result?

Note that all these are happening within powerquery before Close & Apply. Let's say I have 2 tables (Sales left join Employees on Employee_ID) After Merge Queries, Sales will be overwritten in pl...
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lbendlin's avatar
lbendlin
Super User
2 years ago

What made you decide to merge?  Why not let the data model do the work for you?

  • gitgithan's avatar
    gitgithan
    Frequent Visitor
    2 years ago

    I was following a Datacamp course (Data Transformation in PowerBI). 
    Is there no reason to do merging or appending in power query?

    Assuming there isn't, I wonder if there are other operations that combines tables, in which case the question remains.

    • lbendlin's avatar
      lbendlin
      Super User
      2 years ago

      There is no good reason to merge in Power query, only various shades of bad reasons.  Power Query runs on disk and merges tend to slow down the process substantially.  Power BI / DAX runs in memory and is substantially faster when you utilize the data model.  Your first choice should be to utilize the data model.