Asynchronous Script - Running Through Buffer Multiple Times?

Is it possible to run through a buffer multiple times in an asynchronous script?

Let say I have a data set and I want to get the max value and then compare/subtract each row in the data set to that max value and add that as a new column - is that possible in the asynchronous script?

Basically I would need to run through the buffer once and pull out the value for the max, and then go through the buffer again pushing to the output buffer the row with the new column "DiffFromMax".


I already tried adding an asynchronous script to pull the max and put into a variable and downstream add a derived column which subtract from the variable but it doesn't work as the variable cannot be assigned till the postexecute() so its always too late.

I've tried having an asynchronous script that has 2 output, one containing the max and the other the rest of the data, however there is no way to subtract without spoofing a cross join which is really slow becuase of the sort required (I still can't believe msft rejected my request for adding a cross join, it had lots of votes and it should be easy to add... I'd code it myself if they let me have a script transformation with multiple inputs)