When is expression in VAR calculated?

[rajulshah]

Hello everyone,

I want to know that does the variables are already calculated before RETURN statement?

For example:

Measure = 
VAR A = SUM(Table[ColumnA])
VAR B = SUM(Table[ColumnB])
RETURN 
IF(TODAY()=DATE(2020,07,11),A,B)

So, in the measure above,
will both the variables A & B be calculated and then the RETURN statement is executed? 
OR 
It would first check the condition and then calculate A or B according to the condition?

I have checked out multiple videos & blogs, but it doesn't answer my question.

Any help is appreciated.
Thanks.

[az38 · Accepted solution]

Hi @rajulshah 

Yes, VARiables are calculated before the RETURN

So, if you do want to reduce amount of calculation you can calculate it inside RETURN statement

Also, I highly recommend you to try both options and compare its in the built-in Performance Analyzer https://radacad.com/how-to-use-rankx-in-dax-part-1-of-3-calculated-columns

[rajulshah]

Hello @az38,

Thanks for the answer. I actually tried to investigate using Performance Analyzer, but wasn't able to conclude properly.

Thanks again!

[amitchandak]

@rajulshah , to calculate it beforehand you might use sumx or calculate.

refer if these can help

https://radacad.com/dax-variables-better-readability-consistency-and-performance-in-power-bi-calcula...

https://powerbi.tips/2017/05/using-variables-within-dax/