How are thumbnails stored and accessed?

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XnXo
Posts: 8
Joined: Mon May 30, 2022 11:45 pm

How are thumbnails stored and accessed?

Post by XnXo »

I would like to understand where xnview stores and reads its thumbnails from. My previous experience with this kind of software is ThumbsPlus, and it seems to keep thumbnail image data in its database, which is based on MS access. The "Thumb.db" file appears to be where it Xn keeps its thumbnail data - I hope so, cos it's almost 5 Gb!

But does Xn make any use of the "thumbs.db" files that Windows generates in folders with img files? Or are those totally extraneous to Xn? I ask because my library is on a portable drive, and when the drive is not mounted, Xn is unable to show any thumbnails, because it can't access the folders. On the one hand, that makes perfect sense - and I can't expect to actually work with a file that is not available. OTOH, if Xn knows the last location of the file, and has thumbnail data and also has (or could have) all the metadata from the file in its database, shouldn't it be able to show the thumbnails in an offline virtual mode?

This makes me wonder if Xn relies on the the Explorer thumbs.db which is missing along with the files.

When the drive is connected, Xn is able to display previously made thumbnails fairly quickly - not immediately on my laptop, but fast enough. And it builds them reasonably quickly too. So it seems Xn would be able to show thumbnails for offline volumes. Is that an option that I'm not seeing?

Trying to see different ways of using the program with my particular situation.

Thanks.
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BK201
Posts: 84
Joined: Fri Apr 06, 2012 3:43 pm

Re: How are thumbnails stored and accessed?

Post by BK201 »

It's fine just to delete Thumb.db and let xnview regenerate it

When I use in-app command "clear all thumbnails", the .db file size is still 2GB, not sure it's some lagacy data or null reference so I just delete it
XnXo
Posts: 8
Joined: Mon May 30, 2022 11:45 pm

Re: How are thumbnails stored and accessed?

Post by XnXo »

Thanks for the reply! When I posted, I wasn't that concerned about the size of the thumb.db file so much as wanting to understand just how xnview used it. And 4 Gb didn't seem TOO excessive. But it is now almost 9 Gb, and things look different!

I also would like to know if xnview makes use of the "thumbs.db" that Windows is always creating in folders that have even one jpg, and that can be difficult to delete from otherwise empty folders. But now I notice, since using xnview, there isn't a single thumbs.db file in any of the folders that xnview is monitoring. So that's curious to me too. Just wondering how it works as I wade deeper into it.

I think I'll delete (or just rename) that 8 Gb thumb.db file and see what happens! :twisted:

I'm expecting that all my thumbnails will disappear, but that my categories and similar will be fine. Am I right?

After I do that, I think I'll move my installation to another location.

Interesting program!
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xnview
Author of XnView
Posts: 37881
Joined: Mon Oct 13, 2003 7:31 am
Location: France

Re: How are thumbnails stored and accessed?

Post by xnview »

XnXo wrote: Sun Jun 05, 2022 2:54 am I'm expecting that all my thumbnails will disappear, but that my categories and similar will be fine. Am I right?
yes, it's in xnview.db
Pierre.
ragazzo
Posts: 15
Joined: Tue Jun 07, 2022 9:32 pm

Re: How are thumbnails stored and accessed?

Post by ragazzo »

Is this true for Mac OS versions also? I have searched my system and don't see any files associated with XnView. Not xnview.db or any thumbs.db associated with XnView. Where would they be set up on a Mac?

Just getting my feet wet so I apologize for any inconvenience. Looks like a good program but the learning curve is steep without a comprehensive guide. Just going to use it as a DAM but so far it looks lean and fast.

Thank you!
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xnview
Author of XnView
Posts: 37881
Joined: Mon Oct 13, 2003 7:31 am
Location: France

Re: How are thumbnails stored and accessed?

Post by xnview »

ragazzo wrote: Tue Jun 07, 2022 9:38 pm Is this true for Mac OS versions also? I have searched my system and don't see any files associated with XnView. Not xnview.db or any thumbs.db associated with XnView. Where would they be set up on a Mac?
yes, please check this thread
Pierre.
ragazzo
Posts: 15
Joined: Tue Jun 07, 2022 9:32 pm

Re: How are thumbnails stored and accessed?

Post by ragazzo »

Merci Pierre! Not sure I would have ever put in the right search query to pull that thread up. Found the files with your help!