Library ver Collections

I found the topic more than helpful. I just found the value in MS libraries. I decided to start using them. That's why i search and found:

Why do we have Collections in Dopus? Or maybe better said, what is the difference?

I know of 2 features available in Libraries.

  1. Windows 7 will index on every thing in the Libraries.
  2. Libraries show up in the File\Open of MS programs.

I have not used Collections in over 8 years. I would like to know how it will help me. I'm a strong believer in dedicated directories. If I use Libraries that will also be a first for me, 30 years.


A collection is a list of files & folders, which may come from anywhere (e.g. several unrelated places), that only contains the things you specifically add to it.

A library is a merged view of several folders, where you see everything that is in those folders together.


I know if I do a test on my question I'm going to ask I will have an answer. I just want to make sure that I have a concrete answer to that could go terribly wrong.

  1. Will a deletion in my collection be a permanent effect on the file or folder.
  2. Same question but for the library.


For 1., you can use Delete REMOVECOLLECTION=auto to remove items from the collection only, without deleting the real data.
You have to modify your DELETE command for that, & you should better make a test before actually using it.

The answer for 2., i think, depends on your general settings for deleting stuff, so things might get actually deletedfrom your library.
So, when you use collections & that command mentioned above, you should be on the safe side.

Deleting always deletes the file, whether in a collection or a library.

You can remove files from collections without deleting them, either by using the command Abr suggests (Delete REMOVECOLLECTION=auto, which will delete files when used outside of a collection, and only remove files from a collection when inside a collection), or by using the Remove From Collection item which is already there for you in the default toolbars:

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I understand! Deleting always deletes the file, whether in a collection or a library I was concentrating too much on the if. If I wanted to only remove the files in the collection. Thank you for your help.


I tried to remove a collection but its a pain. Firstly I dont use the default toolbars, so had to hunt to find it. This function should be available in right-click in my view.
But when I use this method on a folder, nothing happens. If I use it on a file in that folder it is removed ok. How can I remove the whole collection (rather large, many subfolders).
Thirdly, why is flat view disabled in collections? Seems counter-intuitative to me, and suggests using a library instead?
(I've not upgraded to v11 yet)

If you want to get rid of the whole collection, you can select the collection itself (not its contents) and then use the normal Delete button.

Deleting a collection does not delete its contents. Be careful that you are actually selecting a collection and not a folder in a collection, though. Deleting a folder in a collection would delete the folder and its contents, not just remove it from the collection.

Also note that there is a difference between sub-collections and folders in collections. You can have both. They can appear similar if you don't pay attention, so be careful.

You only need to use the Remove From Collection button if you want to remove something from a collection without deleting it.

The Remove From Collection command is in the default right-click menu for collection items. (Note: The menu for collection items, not for the collections and sub-collections themselves.)

You may not be using the default right-click menus. If you're not using the default toolbars or menus then what you see in them is up to you.

The Remove From Collection command seems to work fine on both files and folders in collections. It also works on sub-collections, although it's the same as deleting a sub-collection. (At least in Opus 11. Maybe it changed from Opus 10. I don't remember it changing but I am not sure.)

Collections are already "flat" in the sense they can show files from multiple locations in a single view. Since collections are usually generated on-the-fly and then thrown away a short time later, if you want to see things together in a collection you'd normally build the collection that way to start with, rather than flatten a collection and its sub-collections (if any; usually there are none).

I guess Flat-View in collections could be supported to let you see the contents of multiple nested collections at once. I am not sure that would be useful in many situations, and if you're aiming to do that there may be a more suitable tool for the job.

Collections are good for storing temporary things like Find Results. If you want to have a long-term way to view certain files or directories in a different way to how they are physically stored on disk, collections are not a good tool for that.

Libraries may be a better tool. Junctions/softlinks can be useful as well. Which tool is best depends on what you are aiming to do.

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Thanks Leo. On your advice, I bit the bullet and just hit Delete on the collections top folder. But the warning was that all files will be deleted, not just the collection!!. Pretty scary and I was very reluctant to proceed (4 TB of files in that collection). But ok now.
I do not get why collections dont have flatview - mine was two folder trees (ie lots of subfolders) from two HDDs, that I was trying to view all the contents of, together, in flatview mode. However, you are right that Libraries may be better for that task, and it looks good so far, so I'll switch.

The "Remove From Collection command is in the default right-click menu for collection items" - I had no problem with this, but it was NOT there on folders, only individual items. The "Remove From Collection command" was definitely NOT there on folders, only on single files in v10. I just upgraded from v10 since posting, and have not checked if it changed in v11.

In case you wanna try the junction/link way, windows disk-management or "mountvol.exe" allows you to mount a harddrive into a folder, besides having a letter (which is not necessary at all). I have 3 harddisks mounted to a folder on a 4th disk, like this:

mnt (folder on 4th disk)
disk01 (disk01 mounted here)
disk02 (disk02 mounted here)
disk03 (disk03 mounted here)

Now when using flatview on "mnt" folder (in modus: "mixed - no folders"), you can access the content combined from all 3 harddisks.

ps: Mountvol.exe is handy for doing these things with truecrypt volumes/disks as well, as these are normaly not mountable to folders (but using the truecrypt volume identifiers directly, you can get around that). Needs some playing to get it right, but then works very reliable.

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The forums eating white-spaces, so let me quickly correct this minimal folder-tree. o)

mnt (folder on 4th disk) disk01 (disk01 mounted here) disk02 (disk02 mounted here) disk03 (disk03 mounted here)

That doesn't sound right. This is what happens when I delete a collection:

Are you confusing folders in collections with sub-collections? They are two different things.