Memory issue - IF using calculated measure

[Jaromir]

Hi,

I am trying to calculate a day by day difference in stock values. To do that I have created a calculated measure called PrevStock:

PrevStock = CALCULATE(SUM('data'[stock]); PREVIOUSDAY('data'[date].[Date]))

Based on that measure I can calculate the difference between stocks in the consecutive days (measure):

Change = sum('data'[stock]) - 'data'[PrevStock]

Then I want to display data for a particular month, say February. The problem I am facing is that on 1st Feb "Change" shows a number which is equal to stock amount. I guess when I limit date range it cannot see any previous data so it thinks that "PrevStock" is 0.

I have tried to use IF statement:

Change = IF('data'[PrevStock] = 0; 0; sum('data'[stock]) - 'data'[PrevStock])

But it always runs out of memory. Why is that? How can I solve this? Thanks a lot!

Sample data:

[CahabaData · Accepted solution]

You might consider approaching it in the data model as follows:

* make a duplicate table T2

* in T2 make a calculated column that is (date less 1): PriorDate

Now join your Table to T2 using T1 date field and T2 PriorDate; or possibly even consider a merged table of the two - - kind of thinking out loud here....

* to avoid confusion in field names of T1 and T2 together you might change column name of T2 Stock to PriorStock

via Related method (or possibly the merged table) now you have Stock and Prior Stock in the same record and getting the difference is at your finger tips

[MattAllington]

Dax is not good at row by row comparisons. Take a look at my article here. 

http://exceleratorbi.com.au/use-power-query-compare-database-records/