topic Re: tables append or union? in DAX Commands and Tips

tables append or union?

adavid999 — Sat, 31 Oct 2020 08:53:57 GMT

Hello,

I have several tables with identical fields. So far I have been loading and then appending the tables and then writing/applying my measures (rather than writing the same set of measures for each individual table).

Is this the most efficient/normal way to work with several tables? I.e. is this the norm or is there a more efficent way to to write measures that would say calculate a mean over several tables?

Thanks,

Re: tables append or union?

AlB — Wed, 04 Nov 2020 14:33:38 GMT

Hi @adavid999

What you're doing sounds good. Append the tables in Power Query, so that you have everything consolidated in one table and you can have your measure operate in just one table. If it's tables with the same columns as you describe it doesn't make sense to operate on them separately

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Re: tables append or union?

Fowmy — Sat, 31 Oct 2020 15:41:46 GMT

@adavid999

The best method would be to combine the tables. You can combine all those tables onto a single table using either the APPEND option in Power Query or the UNION function in DAX.

Please refer to below article:

Append: https://docs.microsoft.com/en-us/power-query/append-queries

Union: https://docs.microsoft.com/en-us/dax/union-function-dax

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Re: tables append or union?

adavid999 — Wed, 04 Nov 2020 13:06:55 GMT

thanks @Fowmy and @AlB good to know I am on the right track

Re: tables append or union?

Anonymous — Fri, 23 Sep 2022 01:08:31 GMT

@Fowmy

Between Append and Union which will take less time to load? I am currently using union and my model takes alot of time to refresh. If I switch to append will it be faster?