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Anonymous's avatar
Anonymous
Not applicable
8 years ago

Slow data refresh

Hi,   Normally my power bi file takes about 5 minutes to refresh, but now it it taking at least 30 minutes (and counting). I noticed that the refresh screen is saying that it has (currently) read s...
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Anonymous's avatar
Anonymous
Not applicable
8 years ago

Hi Gazzer I merged a query and expanded one column (i.e. I effectively did a vlookup from one table into another to populate one column). But I don't see why that would cause 20 million rows (and counting) to be read for a table that is only about 115,000 rows?

Gazzer's avatar
Gazzer
Resolver II
8 years ago

What was the join type? 

Left outer?

Full outer?

Something else?

  • Anonymous's avatar
    Anonymous
    Not applicable
    8 years ago

    I would attach a screenshot of the merge but if I click on insert image I don't see a browse diaglogue to select the screenshot file.

     

    Anyway it is a left out join referring to the same table.

     

    The table has 3 relevent fields:

    Contract number

    Timestamp when contract was created

    Related contract number (used if a contract relates to an earlier contract)

     

    I'm then using the merge to create a field to show the timestamp of the "Related contract number" (where one is present)

     

    The table has about 115,000 rows and currently the "apply query changes" dialogue box is showing 258 millions rows and counting!

     

    Thanks,

     

    CM

    • Gazzer's avatar
      Gazzer
      Resolver II
      8 years ago

      The fields with the IDs being used for the join - are there multiples of each value in each field, or are they unique in one of the tables? It sounds like you have a many-to-many relationship.