It has happened to me that I accidentally deleted some documents. While you can restore a collection from a backup, there is no option to not overwrite existing data.

This unfortunately makes it impossible to restore accidentally deleted documents, without also affecting other documents that have changed since you last made that backup. The restore would undo lots of changes that happened after the backup was made.

I think a very effective and simple solution could be to allow only injecting those documents from the backup that do not exist in de target collection. So no document is ever overwritten/updated when the flag is used. This would restore only the deleted documents without affecting the current state of the database.