Efficient way to scan external files?

Nextcloud version: 15.0.8
Operating system and version: Ubuntu 17

I have a large external library that has pictures added and moved, all outside of NC. I found that ./occ files:scan --path=“path/to/folder” seems to work, but it takes 25 minutes with my large library of images. It appears to rescan every single file.

Is there a more efficient way to do this? Thanks.

On NC 15.0.7 and 16.0.1 occ files:scan -? reports that there is an option --unscanned. Have you tried adding that to your scan command?