I edited a photo on one computer. I go to the other computer and in Lighttable I see the old look. When I press F I see a new view after editing on the first computer… When I press F again (and go back to grid view) - I see the old look. How do I update the thumbnail in grid view?
I know a workaround.
Enter Darktable.
Make a small change and go back to Lighttabe.
Then the thumbnail will update.
But how to do it more simply?
Maybe try this option?
Dartable will then ask at startup if you want to use the new xmp:
(or “keep the newest edit”)
Thumbs in the lighttable will be updated with this procedure.
If I understand correctly, the darkroom already reflects the changes made on the other computer.
@DarekK : you could delete all the thumbnails in the thumbnail cache. Depending on how you use the application (I only keep the currently edited set in the DB), this could be good or bad (you probably don’t want to regenerate (tens of) thousand of thumbnails, which could be the case if you keep all the images in the database at all times.
I understand differently.
https://docs.darktable.org/usermanual/4.2/en/overview/sidecar-files/sidecar/
Once an image has been imported into darktable, the database entries take precedence over the XMP file.
I know about the setting. However, the way I understand it, @DarekK wrote:
I go to the other computer and in Lighttable I see the old look. When I press F I see a new view (in the darkroom, on the 2nd computer - my guess) after editing on the first computer (‘the same I saw on the first computer after editing’ - my guess)… When I press F again (on the 2nd computer - my guess) (and go back to grid (lighttable) view) - I see the old look (the thumbnails as they initially looked, before applying the edits on the 2nd computer - my guess)
So, on the 2nd computer the darkroom view is OK (reflects the changes), but the lighttable view is not (the thumbnails are not in sync with the changes). If I understand correctly, that is.
Both computers are connected to he same shared network folder and both are reading the same xmp files.
This is view from second computer, Grid View
And this is view when I press F key (screenshot after cropping and resizing)
For this purpose I only change ColorCalibration on first computer.
My question is “how to update small thumbnail”?
After kofas comment I believe to understand that you want to do this while both DTs are running simultaneously and without restarting them when changing between both?
I have 3 computers :
At the same time only one DT is running.
xmp files are modified only on one computer, but other computers can see exactly the same xmp files.
Small thumbnail is up to date/valid only on the computer on which it was edited.
When I run DT on other computer I can do sort based on modification time and I can see which photos was edited on other computer but I don’t have effortless method to update small thumbnail.
Do you have ‘look for updated XMP files’ enabled? It is required to be able to see the updates made on one computer. Since the darkroom works, I suspect the answer is yes; however, with large collections, it can really slow down opening darktable, as it has to scan the collection for updated files.
Alternatively, you can also have
on a shared drive. See --library <library file> and --cachedir <cache directory> at darktable 4.2 user manual - darktable.
No - ‘look for updated XMP files’ is disabled.
Searching for changes in 50k files over lan takes very long minutes.
DT is different from other programs.
e.g. there is no menu (with option “refresh thumbnails”).
It has various lua scripts.
I thought there was some script or “hidden” button that would update/refresh that very single thumbnail.
Database is syncronized via Synology Drive (works like private Dropbox).
Putting cache on network drive is idea worth considering.
Thank You. 
kofa - THANK YOU.
Works.
Not as fast as cached on local drive (nvme vs 1Gbit lan), but surprisingly fast. Fast enough.
Darek
you also might setup an script using darktable-generate-cache that runs e.g. nightly in the background to keep cache quite up to date
I don’t know if you are aware of darktable 4.2 user manual - local copies, and if they could be applicable to your use case. I only edit on my main computer, so have no hands-on experience with the feature.
How would it work with local cache and database on the network drive? Normally, the cached previews should be generated when the database shows a change, and with local cache you avoid quite a bit of network traffic.
I think the trouble is:
So darktable does not realise the thumbnails are out of sync with the DB.
