What triggers digiKam to rebuild all the thumbnails?

[Elle Stone]

When opening digiKam, what triggers digiKam to rebuild all the
thumbnails (a very slow process on my old computer)? I thought it was
if the filemodify date/time had changed. But I guess I was wrong.

I have "Scan for new items at startup" checked, but it seems that
"new" means more than "new images". It also seems to mean "images that
changed in some way". But what is the "some way"?

I copied some metadata over from the digiKam xmp sidecar files to the
image files using exiftool with the "-P" switch, which preserves the
file modify time. I was hoping that digiKam wouldn't feel obligated to
rescan and rebuild the thumbnails if the file modify data hadn't
changed, but it scanned and rebuilt all the thumbnails anyway.

Are there any bad effects from unchecking "Scan for new items at
startup" and just scanning on an album by album basis when I actually
add new items?

Elle Stone
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[Marcel Wiesweg]

> When opening digiKam, what triggers digiKam to rebuild all the
> thumbnails (a very slow process on my old computer)? I thought it was
> if the filemodify date/time had changed. But I guess I was wrong.

A change of the file size is an even more reliable indicator that the file
changed than the modification date...
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[Elle Stone]

So is a change of the file size what digiKam actually uses to decide
that an image file has changed? Does it check anything else?

On 10/24/12, Marcel Wiesweg <[hidden email]> wrote:

>
>> When opening digiKam, what triggers digiKam to rebuild all the
>> thumbnails (a very slow process on my old computer)? I thought it was
>> if the filemodify date/time had changed. But I guess I was wrong.
>
> A change of the file size is an even more reliable indicator that the file
> changed than the modification date...
> _______________________________________________
> Digikam-users mailing list
> [hidden email]
> https://mail.kde.org/mailman/listinfo/digikam-users
>

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[Marcel Wiesweg]

> So is a change of the file size what digiKam actually uses to decide
> that an image file has changed? Does it check anything else?

We check modification date and file size. These are readily available when
stat'ing a directory.
Thumbnails are identified "by content" which means a hash over parts of the
file and the file size.
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