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DataGuy2016's avatar
DataGuy2016
Advocate IV
9 years ago
Solved

Table Merge creates duplicate records

Hi Folks,   I am stumped.   I am trying to merge two tables into a new table using a LEFT JOIN.  Both tables have unique records on each row.  When I join the tables, BI creates duplicate rows on...
Need Help
  • DataGuy2016's avatar
    DataGuy2016
    9 years ago

    The problem lay with the Data.

     

    The LEFT JOIN functionality of PowerBI works perfectly.

Anonymous's avatar
Anonymous
Not applicable
4 years ago

I work with very extensive datas sheets and as soon as I tried this solution (that works pretty well) the uptade started to take hours to be conclude, thats the only issue Im having right now... Any clues about that?

Anonymous's avatar
Anonymous
Not applicable
4 years ago

Having the same issue. Performance severely degrades when I use this method. It works in theory, but in some cases will take forever. 

  • othmanalazzam's avatar
    othmanalazzam
    Advocate I
    4 years ago

    hello there,

    the slowness is not coming from adding an index column or removing the duplicate, Power BI and Excel Power Queries are always having a problem when using the "Merge" method, this is happening because "merge" includes a "reference" step inside of it, this specific step "reference" is a performance killer, it really slows everything down in a horrible way, the only two solutions I found to this problem is either you find a workaround to this and try to achieve your result without using "merge" or "reference" (a workaround that does the same effect and I have done that sometimes), the other solution is to not use it all together, there is really no way to optimize the "merge" itself.

     

    Regards,