>must choose "files folder events" in combo and "all locations" option ("no").Any modification on any file on PC is trapped here but
>this recquires the application must run on background all time (service?) to trap all windows messages occured and update the first scan table online
>the search result becomes runtime at this step.
>a complet scan maybe must be applyed at some long interval (one per week maybe for ex.).
>
>have you experimented this kind of monitoring ?

I had to, in https://www.levelextreme.com/Home/ShowHeader?Activator=17&ID=40436, but only for a selected set of folders (still, with about 100-200,000 files). While it was decently fast on local drive, it was just unbearably slow on a network drive (actually a fake network share on linux host, scanned from a W7 virtual box).

The only speedup was that for each folder I'd compare the last update date with what I had in the folders table, and if it was the same, I didn't check the files in it. Still not fast enough, so what you can see in the download is now split into two processes - one to scan the folders, and one to display the files (images, in this case, it's a screen savior) from locations saved in two dbfs.