a couple quick questions about dopus thumbnail cache in %localappdata%.
does it ever clean itself out of images that no longer exisit?
if it doesn't clean up automatically is there a way to have dopus check it manually? other than deleting it and starting over.
i work with a lot of images, its massive, nearly 5 gigs.
You mean /dopuslocaldata\Thumbnail Cache?
Its size limit can be set in Preferences / File Display Modes / Thumbnails / Performance (Thumbnails).
yes that cache.
is this strictly a size setting? does the oldest get pushed out when the limit is ready regardless of if a indexed directory still exists?
I'm trying to wrap my head around how this cache is stored.
back story...
I run regular back ups of my all my appdata folders a few times a week.
yesterday I was processing, converting and moving, between drives, about 15,000+ images. these images went from an hdd, to a sdd temp\processing dir, before being moved to their destination.
when i ran a back up this morning the thumbnail cache increased by 1.8g from 3 days ago. I dont mind that its 5+g per say as long it is storing a relevant index.
need to come up with an articulate question here...
does the cache store reference via absolute location only? if it does than there are two large ghost folders just sitting there.
or does the cache use Checksums to reference images that have been moved around between 3 hard drives?
I guess it gets pushed out when new thumbnails are generated, but i doubt that it would distinguish between obsolete data and the kind that would be still useful. In order to achieve that, Opus would have to perform some sort of audit, evaluating your whole collection of images and folders.
hmm, I feel the out with the old in with new is likely and simple.
thou comparing hashes is simple too. everything has this search syntax that returns ressults in seconds. it even return duplicates with different extensions. e.g. jpg vs jpeg vs webp if they've been converted without changing anything else in the image.
D:\My PICTURES\ dupe:size;sha256 you can all also add ext:png etc to narrow it down.
I generate big thumbnail caches as well and always feel a pang of sadness/regret when I have to delete and rebuild. 
ditto. I might be a media hoarder. lol. I've 20tb of everything in one box
Thumbnails are stored in separate files for each source folder. The name of the cache file is based on a hash of the folder path, which means if the path is moved or renamed the cache for that folder will need to be regenerated.
When the total cache size exceeds the configured limit, cache files are deleted based on when they were last modified (oldest first) until the total size is within the limit again.
thanks for clarification.
that's tough . the 1st to go will be folders I likely don't move around.
ahhh I miss old win 7 when the Thumbs.db stayed hidden in the folder. 