Forum Discussion

some1else's avatar
some1else
Helper II
3 years ago

This calculated column makes everything slow

I've followed this blog post to make a calculated column of my own, applied to a table of 3million rows. https://community.powerbi.com/t5/Community-Blog/Mean-Time-Between-Failure-MTBF-and-Power-BI/b...
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some1else's avatar
some1else
Helper II
3 years ago

Wow, thanks for the extensive reply, I will look into it tonight.
Using the calculated column and the measure I get different results:

Even the calculated column has some weird values. Look at the 5 and 6th rows, the MTBF should be 0, not 2283hours which is the MTBF between the 7 and 6th row. Any ideas?

Greg_Deckler's avatar
Greg_Deckler
Community Champion
3 years ago

some1else It's going to be extremely difficult to troubleshoot this without some sample data as text and your measure formula.

  • some1else's avatar
    some1else
    Helper II
    3 years ago

    Sample data at the end. I want to look at just one specific code "A1".
    If you look at the sample, by the measure only method all calculations are wrong. By the calculated column way, Machine1 seems to have the proper MTBF, but Machine2 is way off...

     

    Calculated column has this code:

     

     

    Uptime = 

VAR next =
    MINX (
        FILTER (
            'TABLE',
            'TABLE'[Machine] = EARLIER ( 'TABLE'[Machine] )
                && 'TABLE'[actstart] > EARLIER ( 'TABLE'[actstart] )
                && 'TABLE'[failurecode] = "A1"
        ),
        'TABLE'[actstart]
    )
RETURN
    IF (
        'TABLE'[failurecode] <> "A1",
        0,
        IF (
            ISBLANK ( next ),
            DATEDIFF ( 'TABLE'[actfinish], NOW (), SECOND ),
            DATEDIFF ( 'TABLE'[actfinish], next, SECOND )
        )
    )

     

     

     
    Measure has this code:

     

     

    MTBF (Hours) = DIVIDE(SUM('TABLE'[Uptime]),[Repairs],BLANK())/3600

     

     

     
    By the Measure only method this is the code:

     

     

    MTBF (Hours) Measure = 
VAR __table = 'TABLE'
VAR __table1 = 
            ADDCOLUMNS(__table,"__next",
                MINX(
                    FILTER(__table,
                            'TABLE'[Machine]=EARLIER('TABLE'[Machine]) && 
                            'TABLE'[Machine] = EARLIER ( 'TABLE'[Machine] ) && 
                            'TABLE'[failurecode]="A1"
                    ),
                    'TABLE'[actstart]
                )
            )
VAR __table2 = ADDCOLUMNS(__table1,"__uptime",
                    IF('TABLE'[failurecode]<>"A1",
                        0,
                        IF(ISBLANK([__next]),
                            DATEDIFF('TABLE'[actfinish],NOW(),SECOND),
                            DATEDIFF('TABLE'[actfinish],[__next],SECOND)
                        )
                    )
                )
VAR __repairs = CALCULATE(COUNTROWS('TABLE'),FILTER(ALLSELECTED('TABLE'),'TABLE'[failurecode]="A1"))
RETURN
DIVIDE(SUMX(__table2,[__uptime]),__repairs,BLANK())/3600

     

     

     

    Sample:

    https://www.dropbox.com/s/k9a7ikcxfnwswhl/Sample.xlsx?dl=0