Thumbnail Caches transferred to new computer not used

[klownboy]

Hi Don, last week I bought a new computer and copied everything concerning XYplorer (exact copy) to the new computer - same folder (D:\Tools\XYplorer) - which in my case is also the <xydata> folder, same thumbnail folder (D:\Tools\XYplorer\Thumbnails). My pictures were placed in the same locations as my old computer "H:\Pictures" along with all the sub-folders. I made sure Configuration pointed to the same thumbnail folder for the cache and all the thumbnail options were the same. I know the thumbnail cache folders names are simply the hash of the picture folder, *, and the thumbnail size (e.g., H:\Pictures\Ireland\2011-06-29\*240x240). However, XY insisted on making new thumbnails when I traveled to my picture folders. It kind of bugged me at the time because I have thousands of photos. It's done and over now. I've generated new thumbnails, but I'm still wondering if there was something else in play that I missed as to why XY generated new thumbnails and didn't use the existing caches I copied. Any thoughts or insight on that?

[m48tx]

I have noticed the same sequence. I speculate it has something to do with the creation of the folder on the new system. It seems date/time is not the same as the original folder. The files are the same, but not the folder. This leads XY to recreate thumbnails?

[klownboy]

I have noticed the same sequence. I speculate it has something to do with the creation of the folder on the new system. It seems date/time is not the same as the original folder. The files are the same, but not the folder. This leads XY to recreate thumbnails?

I'm not sure obviously, but I suppose it's possible. As I mentioned before, the cache filename for the picture folder is simply the hash of "image folder*thumbnail size". I'm not sure how the folder's date or file dates (creation or modified) would come into play. Unless XY does look at the date/time, figures they're off so rebuilds the caches. The XYthumbs.txt file which lists all the cache files does have a time and date, "2020-01-30 08:25:20" at the top of the file, but I don't believe that is used in any way other than the date and time being changed when new caches are made or rebuilt. I guess Don would have to weigh in. Not a big deal, though it would be nice to know if I have done something wrong or if there is something I could do differently the next time (not that this happens too often). Thanks.

[admin]

Yes, the date is relevant. If the modified dates changes XY assumes that the file has been modified and refreshes the thumbnail.

[klownboy]

OK thanks Don. So in the future if I make sure I transfer all the photos and the thumbnails caches maintaining the the existing dates/times, theoretically it should work? Actually, I thought that's how I had the file copying options set. Are you saying the folder modified dates is also important in this case or are you referring strictly to the image file modified dates?

[admin]

I think it's just the files (no time to check ATM). Did you recheck whether your file times are kept as they were in the source?

Anyway, I guess I will make that date-check optional in future...

[klownboy]

Thanks for getting back. For your info, I know I used preserve dates on custom copy when I did transferred the image files last week. I'm not positive, but I think I may have made a new folder (Photos) on the new computer and then copied the many sub-folders into that Photos folder. So if that's the case the folder structure may have appeared different to XY and therefore rebuilt the thumbs.

In any case today I ran a test. I made a temporary thumbnails cache folder and reflected that on both the old and new computer. I then copied a bunch of image to some new temp image folders and built thumbnails for them in the new locations. I copied both the image folders and the images preserving dates for both and transferred them via flash drive to the new computer. I also copied the temp thumbnail cache folder. After setting the folder view for the newly transferred mage folders to a thumbnail view, all the thumbnails appeared already built. So, as long as the complete folder structure and images are maintained with the preserved dates, it does work.

I believe in my situation it may have only been the folder creation date(s) that may have messed up the transfer and use of pre-existing thumbnail caches since the images and the sub-folders were copied preserving dates.

It would seem to make sense to have an option to ignore dates for situations like this anyway. In your everyday use though, you would probably still want XY to detect a modification to an image (e.g., it was trimmed or cropped or whatever in an external program but you keep the same name) so the modification date changed.

[admin]

Thanks for the test and the confirmation that it works.

Yes, ignoring the modified date is probably not a good solution. Ending up with more and more stale thumbs is worse the redoing once them after migrating them to a new system (which won't happen too often).

[klownboy]

Yes, it's probably best to keep things as they are.

For historical purposes for anyone migrating XYplorer to another or new computer and wanting to maintain the thumbnail cache without having to rebuild all your thumbnails, please read my entry above. Bottom line is make sure all your files are transferred preserving dates (Configuration option). That goes for everything associated with XYplorer (including your thumbnail cache folder) as well as all your images files - the files as well as the folders must have the same date/time and in the exact same folder/locations as the other computer.