Optimizing Measure performance (open incidents running total)

Dear All,

A couple of days ago I posted a topic for help with a measure which calculates the number of open incidents per day. I've already made some small adjustments since then.

• https://community.fabric.microsoft.com/t5/DAX-Commands-and-Tips/Open-Incidents-per-day/m-p/3968348

Objective of this measure is to calculate to number of incidents where the last status in the filter context of the visual is not closed.

The measure I created works in the sense that it shows the correct results. However, already in my test-environment which is only ~15.000 rows, the performance isn't great.

When I attempt to run the measure in my live environment with ~15.000.000 rows, it's completely un-useable, as in, I just get an error that it runs out of memory. 

As far as I can see there are 2 issues:

• The number of iterations on the facttable 
• A rolling date range is intensive as the datasize keeps getting larger day-by-day (_Date[Date] <= MaxDate)

I'm however at a loss on how to calculate this result in a different way. What would be the correct way to re-write this measure so that it's usable in a larger data-model?

For reference, my fact table (Raw_Transactions) looks something like the screenshots below.

Only connected table is a date table called '_date'.

Thanks in advance for the assistance!

Open Incidents (Summarize) = 

VAR MaxDate = MAX('_Date'[Date]) 

VAR Result =
CALCULATE(
    COUNTX(
        ADDCOLUMNS(
            SUMMARIZE(
                Raw_Transactions,
                Raw_Transactions[IncidentId],
                Raw_Transactions[CountOfTransaction]
            ),
            "@MaxTransaction", 
                VAR _Result =
                CALCULATE( 
                    MAX( Raw_Transactions[CountOfTransaction] ), 
                    ALLEXCEPT( Raw_Transactions, Raw_Transactions[IncidentId] ),
                    _Date[Date] <= MaxDate
                )

                RETURN
                IF(
                    _Result = Raw_Transactions[CountOfTransaction],
                    _Result
                )
        ),
        [@MaxTransaction]
    ),
    _Date[Date] <= MaxDate,
    Raw_Transactions[TransactionType] <> "Closed"    
)
    
RETURN 
Result