You want service on the weekend sign up with your support provider for priority service, and learn just how much "urgent" costs. This is an all-volunteer site whose members post when they can, and usually only if they have something to contribute. Things like your "bump" are offe...
Given the size of OVER.30 and the fact that the complaint is not one of failure, we can assume 64-bit addressing. An answer to the "append/overwrite" question is keenly awaited before speculating further.
Would you use a crowbar to fasten a rivet? Use the correct tool for the job. In this case the correct tool is either the Remove Duplicates stage or the unique option in a sort.
You could push the sort out into the database server and use a Sort stage to assert that the data are already sorted. This can take advantage of any index on the sort key column(s).
As this article shows, Iconv() is rather agnostic about such niceties. All you need is the order of the components to be right. Iconv(InLink.TheDate, "DMDY") will convert any date in any legal format in month-day-year order into DataStage internal format (number of days since 1967-12-31).