Benchmarks using MODIFY to update in place?

[elspethB]

Has anyone any benchmarks for the MODIFY statement? I have a 51 million row SAS dataset that I need to update 3 fields on. A test run on 10,000 rows took 21 minutes CPU time. Extrapolating, it is going to take roughly 1750 hours to update the whole file. I hope this can't be right.

NOTE: I want to use modify instead of a merge creating a new data set so that the indices don't have to be rebuilt.