Lets say we mimic the behaviour of a many-to-many relationship between Users and UserGroups, and we're storing the ID's of which UserGroups a User is in, in the User document within an array. Now when i delete a UserGroup then the ID of that UserGroup will still be in the Array in the User document - does it affect the perfomance at any point, that it's holding some old and useless values in the array?
I've come to the conclusion that a Document-oriented database isnt made for relationships. I've instead decided to use a object-oriented database instead (db4o).