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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...
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  • 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

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,