You must be looking at a different function to me. The output from the
arraydifference( function I see is a new array which leaves both of the input arrays unchanged.
The original ProVUE code took 24 minutes to process 250,000 records. My modified code took 29 minutes.
I replaced this code:
arrayfilter both,both,sep,?(import() = array(both,seq()-1,sep),import(),"")
and it works.