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Concatenate 2 columns - (merging 2 columns) > 40 mil records



Fact table - >50mil records - to make 1 to * relation (I am trying to get Operational acc description)

DIM table - OperationalAccount+Chart of Accounts (Compound key to get unique record for description)


Now when I Merge OperationalAcc + ChartofAccounts in fact table - and Apply changes - it is stuck after say 20 mil records and never finishing - I tried several times. 

Is there a better way to handle this?  To apply for all the records in less time or is it possible to handle in M query ? 


Which is better performnance wise - in
1. Power Query - via visual editor (dupplicate 2 columns and Merge?

2. M Query editor - new column -- ColumnA & Column B 


Thanks Krishna


Super User
Super User

Hi @krishnabodapati,


If you have a fact table and a dimension table you do not need to make the merge. You can create the surrogate key with both columns and then using the relationship between both tables you are able to make all your visualizations with the details you need.


Not sure if this helps but my understanding is that you are merging the tables to have the description picked up from the dimension is that correct? 


Miguel Félix

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