[Cosmo-dev] more fun with items in multiple collections

[Jeffrey Harris]

Hi Folks,

Can someone remind me what we'd like to achieve by having items with the
same UUID in different collections be persisted in the same way?

Benefits (off the top of my head):
- Use less bandwidth (this seems like a relatively small issue)
- Make changes to items atomic (big issue)

I'm still enamored of separating items based on what user's collection
it lives in (basically using a database key like home_collection:UUID).
 When considering these goals (I'm sure there are more, so I know this
is an incomplete picture), I think this approach would get us a lot of
the benefit, with fewer security problems.

If I had an item in a collection owned by me and also in a collection
owned by someone else I'd have to sync twice, so there's a loss of
atomicity, but I think there's just no way for the server to know if
those items are REALLY the same.

I think there are lots of use cases where I have private changes to a
public item.  For instance, notes on PyCon sessions, which ones I'm
attending, what I liked, etc.  I don't want to change my UUID for the
item, because I still want to merge in changes to the public event
(like, for instance, room changes).

In a global sense, I think there are really multiple items in play here.

Sincerely,
Jeffrey