Lightroom: Not cleaning up properly after deleting/dereferencing an image

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  • Problem
  • Updated 2 years ago
  • (Edited)

recently asked me what was happening with the preview file when the
user is deleting or dereferencing an image. A good question that needed
some monitoring. What I have found is the following...

importing an image, if the user has requested the creation of the 1:1
preview, LR creates two preview files which are named after the global_id of the image in the database (the global_id
is an identifier that never changes as long as the image lives in the
catalog - it cannot be the file name because the image can be renamed or
because two different images in different folder can have the same
name). The name of the preview is the result of the concatenation of the
global_id with another value representing the preview, the "digest". So
you get something like that : CA4C526B-898B-4D58-8DBC-B035356BB141-5e7425c24caa33e18b8e99baf98dfe6b.lrprev (global_id-digest.lrprev).

The previews are stored in a subfolder which name is based on the 4 first digits of the global_id, here \nomCat\nomCat Previews.lrdata\C\CA4C. As
mentioned above, two files are created, one for the standard preview
and one for the 1:1 preview, the latter being much bigger.

Now, if I delete or dereference an image in LR, only the standard preview is deleted.
The 1:1 preview will only be deleted if a catalog optimization is
triggered or when LR does its 1:1 previews cleanup (each day, each week
or each month, according to the catalog preferences).

So if you have set this setting to "Never", you may find yourself after a while with a lot of useless 1:1 previews.

Why doesn't LR delete the 1:1 preview immediately when an image is deleted or dereferenced?
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Patrick Philippot

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  • frustrated

Posted 2 years ago

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jochen strobel

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Hi, why not see that as a kind of last chance backup? That said, I do catalog optimisation so often that it doesn't bother me.