> A full rescan on a complete mame collection takes 90 seconds on my system. ...So
> I don't see a real need for such an option ;) Besides it would have to do major
> analyzing of the old and the new datfile to capture all possible changes....so a
> simple rescan when a datfile has changed is the easiest to do.
>
Well..roms located on another computer...slow windows network...slow harddisk...makes 45min for MAME set to scan...so I woudl gain a lot of time from that ;)

> Well...hmm....It may be possible to create some hashvalue on the setdata (number
> of roms, parentname, romnames, etc..) and compare that with the data in the new
> datfile. If it matches, don't rescan it. The problem: You don't know if
> something or someone else has changed the data on your harddisk. So you better
> do a rescan anyway.

That problem does already exist, because if you do a Fast Scan now, you don't know, if all the excluded sets have been changed or not...