Good way to clean up old previews?

[DavePinMinn]

Lightroom Classic 12.5, Windows 11 Pro

My Previews.lrdata "file" seems abnormally large.

I had Lightroom delete any Smart Previews that might be lurking.  I believe it found 72, and they're gone.

I did the same thing with 1:1 previews, so they're gone.

A search in the previews file shows around 250,000 preview files (standard?), which is 2 - 3 times the number of images in the catalog, about 70,000 of which haven't been updated since 2020.

Is there some intelligent way to remove old standard previews and other junk in the previews file rather than deleting the whole thing and making Lightroom start over?

I presume Lightroom always deletes any previews associated with a file it deletes, but is there a way to check or have Lightroom check that orphan previews DON'T exist in the catalog - and delete any that are there?

[dj_paige]

In the Library Module, use Library->Previews->Delete 1:1 Previews

Typically, Lightroom Classic generates several different sizes of previews, which can be the reason you have 250,000 when you have about 70,000 images.

[bob frost]

In the past the different size previews of an image were included in one file - the .lrprev file. As I understand, from a different thread, the use of separate size preview files only started in LR 13.5. DavePinPin is using LE 12.5, so the extra files he has should not be separate size previews. Its easy to see - just look in a preview folder. If it has all .lrprev files, there should only be the same number as your images. If it has loads of separate size files with no extension, then each image file should result in several several size files. My LR13.5 has produced six preview files for each image, with -80, or -160, or -320, or -640, or -1280 or -2560 at the end of each name.

After converting .lrprev files to the new format files, my LRC left 1349 .lrprev files untouched. I deleted these as I believed they were orphaned previews. After doing this I ran the 'Build Standard Previews' command  and it said there were none missing, and LRC runs fine.

bob frost

[Conrad_C]

Not sure, but it might help to run File > Optimize Catalog. That’s supposed to clean up the database, and things like orphaned database entries. But I’m not sure how thoroughly that extends to the preview files that the database manages. However dj_paige is correct that there are probably multiple preview files per image, at the very least a standard preview and a grid thumbnail size preview, but more likely previews at multiple zoom levels and grid sizes that might have been used.

I just give up and throw out the entire .lrpreviews when it gets too big, even though that causes a delay when they are rebuilt as I view each folder again.

[DavePinMinn]

Thanks for the replies...  Yes, as the original topic said, I DID the Delete 1:1 previews AND Delete Smart Previews.  Those are all gone presuming the deletes worked.

The catalog gets optimized every time I back it up, which is weekly.  I'm not sure how thorough it is either.

If the only answer is to blow away the whole previews when it get unwieldy and rebuild it, I'll probably go back to a separate catalog for incoming images.  Only the "good" images ever got imported into the actual catalog and I didn't see the rapid growth.  And when there were no images waiting for culling, I could delete the previews file on the Incoming catalog and it was clean.

[KR Seals]

Is your issue with the large number of previews the size they take on disk? On a Win 11 machine, it should be possible to replace the C: drive with a larger one or add an additional (large) SSD that you can use to run LrC and the previews from.

One solution to the issue of LrC taking all that time to create previews is to not import the whole shoot if you are going to cull a large amount of the images in LrC. I do a pre-cull on my images from large shoots with Photo Mechanic which is very very fast at copying the images to the specified drive/folder. It is also FAR faster than LrC for culling. That way, LrC does not have to make previews of images that will just be culled out and deleted.

[DavePinMinn]

Mostly I'm conerned about how much unnecessary, inefficient junk is being left sitting around.  If the answer is NONE, then yeah, shove more hardware.  But if there's a lot of stuff that can be cleaned up WITHOUT nuking the whole catalog of previews, I'd prefer to do that.

[Ian Lyons]

Using only LrC, the easiest way is to just trash the Previews.lrdata folder, but rebuilding them is time consuming. However, there is a plugin by Jeffrey Friedl that includes an option for removing redundant previews. You can read more about it at http://regex.info/blog/lightroom-goodies/bag-o-goodies

The option you would need to use is 'Delete cached previews...'

http://regex.info/blog/lightroom-goodies/bag-o-goodies#delete-cache

[JohanElzenga]

The latest version of Lightroom Classic regularly deletes 'out-of-date' previews already. Note that 1:1 previews are only really deleted if they are at least twice the size of standard-sized previews. If they are smaller, then Lightroom won't delete them but use them as standard-sized previews. Also note that there are different size previews per image, so 250,000 previews for 70,000 images does not mean this is all obsolete stuff that was left behind.

[DavePinMinn]

Thanks.  I'll take a look at the plug-in.  If that doesn't work as hoped, I'll just blow away the previews.  I know this is how we've always had to do cleanup in Lightroom, but it always seems like swatting a fly with a sledge hammer.  After this many years, and versions, it seems like there would be a more elegant method of managing the catalog data.

[Lucas-FoxyVisions]

I'm guessing that this doesn't work for MAC users does it?
I'd love to keep the previews from last year, and I only have from last 3 months since I'm doing so many photos and then ofloading them to my big storage where stuff is just sitting in dust. 
So I'd love to just delete any of the older previews but not the ones from last year til now...

[DavePinMinn]

In the end I concluded that the simplest solution is probably the best.  I went back to having 2 catalogs.  One for "good" images that have been culled, and one for Incoming images. 

It would be nice if there was a way to import from one catalog to another, so all the stuff that's catalog-only and not persistent in the metadata would get moved too, but I haven't found a way to do that.

[Abambo]

In the end I concluded that the simplest solution is probably the best.  I went back to having 2 catalogs. 

By @DavePinMinn

That is, in my eyes, a complex solution. But if it works for you…

It would be nice if there was a way to import from one catalog to another, so all the stuff that's catalog-only and not persistent in the metadata would get moved too, but I haven't found a way to do that.

By @DavePinMinn

Whatever that means… When I'm travelling with my laptop, I use an external disk, where I import my catalog into my main system. Unfortunately, not all catalog data get imported (like publish services) so that I have an alternative solution for my two desktops.

[DavePinMinn]

It has some advantages...  It separates the previews from the real catalog from the Incoming stuff where there's a LOT of 1:1 preview generation and fiddling while doing culling.  And when there's nothing in that catalog, I can blow away the previews file and everything is clean for the next import.

It also makes it automatic to send the good images to the backup when I import them into the real catalog.

It was always pretty painless, except for losing stacks, when I used it, but I kept reading "you should only have 1 catalog", so I tried it.

When you get home from traveling and import your catalog into the main system, can you import a SINGLE folder into the main catalog or do you have to import the WHOLE catalog every time? 

[JohanElzenga]

Yes, 'Import from Another Catalog' allows you to select which folder(s) you want to import and which folder(s) you don't want to import.

[Abambo]

I import the whole stuff, but exclude obviously duplicates.

[bob frost]

In another thread I read that if you use 'Export to another catalog'  with previews (but not images), it leaves behind any rubbish in the catalog, but also in the previews. I've done this in the past to get rid of rubbish in the catalog and improve performance, but I haven't done it with the previews. Worth a try.

Bob frost

[JohanElzenga]

What's the point of doing that? You can simply delete the previews of the current catalog if you want to 'clean them up'. In both cases Lightroom rebuilds the previews, so there won't be a difference. Remember that exporting as catalog does not bring over any publishing services, and can create a problem if your catalog is synced.

[bob frost]

Deleting the current previews is simple, I agree. But regenerating them if you have a couple of hundred thousand files takes ages, even with the current ability to generate previews in parallel. If you include previews in an export to another catalog surely it just copies the existing previews rather than rebuild them as you suggest?

Bob Frost

[JohanElzenga]

Maybe they will indeed be copied rather than generated, but in this case you might not want copied thumbnails, because then you will still get many of those old versions... The loss of publishing services and possible sync problems is much more important, however.

[bob frost]

Hi Johan, I don't use publishing services and wouldn't even dream of syncing my images to the cloud! I know, I'm a dinosaur! I don't know whether the copying of previews during and export of the catalog to a new catalog does clean up the previews. I was just reporting what someone else said in another thread. 

I used to manually cleanup the catalog using SQlite DB browser until I heard that exporting the catalog did the trick. I have had to do this a few times over the years, usually after an upgrade to a new version catalog. I have not had to do this lately, so LRC must have improved its upgrade process. As to cleaning up previews, I still do that manually. It was usually simple to spot previews that are incomplete or duplicated, and delete them. This current conversion of .lrprev files to separate-size files without an extension has left me with a lot of .lrprev files that I have deleted manually without an effect on LRC behaviour. I suppose I could use my last week's backup of LR to test whether exporting the catalog with previews does cleanup these leftover .lrprev files (assuming they are leftovers!). 

Do you know why the .lrfprev files have not been converted? Is it because they only contain one size of people preview already?

Coming back to your point about publishing services and syncing, couldn't Adobe sort this out so that exporting a catalog didn't upset them? And couldn't Adobe give us a good repair tool for catalogs? They do repair some catalogs, so they must have one.

Bob Frost

[JohanElzenga]

I am not sure, but what I do know is that 1:1 previews are not discarded, but used as standard sized previews if they are smaller than a certain size (don't know by heart what the exact formula was). Maybe the lrfprev are those kind of previews, but that is just a guess.

Publishing services are apparently quite tricky. Once it has been setup, you can't change the destination folder of a publishing service to your hard disk, for example. Another problem would be that if you could export a publishing service to a new catalog, then the destination of that service would now be linked to two different catalogs, which can cause all kinds of problems with services that link to online destinations, but also with local services. Suppose I would edit the image in catalog A, and then republish the image because of those edits. Then the image in catalog B would not be up to date with its published image anymore, but how is catalog B going to know that? And what should happen if it did know?...