Remove preview files without occ and without posix

The ‘preview’ files folder somwhere below data dir is getting quite large. How can I clean up this folder, causing the previews to disappear, but be regenerated when necessary?

I tried the following:

  • remove the preview folder
    -> this causes the previews to disappear without being regenerated, not good
  • remove the preview folder, then run occ
    occ is not an option as my hosting company does not has posix tools enabled

Can I, somehowe, remove the preview folder, and cleanup the database, so that the files are generated when necessary?

Thanks

for example, can I remove the preview folder, and all references to it in the “filecache” table? (with “preview” in the path)?

I have done the following procedure with success:

  • backup everyting (datadir + database) before you attempt this
  • remove folder data/appdata_ocpb8d7vbr73/preview (appdata_ocpxxxxxxxx/preview)
    (only the preview dir!)
  • on the database, execute:
    delete from oc_filecache where path like ‘appdata_ocpb8d7vbr73/preview/%’;

Now the previews are gone freeing the diskspace. When a user visits the folder and diplays previews, the previews are regenerated for that folder.

Note that this slows down nextcloud significantly, until previews are generated again, i.e. when previewing a folder for the first time.

Note also that, while i have tested this procedure with nextcloud 12.0.3, it is most probably not supported by the Nextcloud team :slight_smile:

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I’m interested in that issue too.

Normally the preview images were deleted automatically when the originating file is deleted. This is the theory.

But if you have really a lot of files this does not work.

@rullzer @nickvergessen can you confirm the method of @Stijn_Haezebrouck?
Or is there an easier way, e.g. an occ command?

Thank you!

While it should work, no guarantees that it might not cause temporary troubles.

No, there is no “easy” way

So it would be a nice extension to the occ files:cleanup command.

Does this mean that the method of @Stijn_Haezebrouck is correct and the only way @nickvergessen?

For anyone looking for a quick way to accomplish this via script, here’s what I use. Granted, it’s Docker, but you can modify as required.

#!/bin/bash

du -sm /data/docker/containers/nextcloud
docker exec --user www-data nextcloud php occ files:cleanup
docker exec --user www-data nextcloud php occ versions:cleanup
docker exec --user www-data nextcloud php occ trashbin:cleanup --all-users
rm -rf /data/docker/containers/nextcloud/apache/data/data/appdata_*/preview/*
docker exec nextcloud-mariadb /bin/bash -c "echo 'delete from oc_filecache where path like \"appdata_%/preview/%\";' | mysql -u nextcloud -pPASSWORD nextcloud"
du -sm /data/docker/containers/nextcloud
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