Canvas "obfuscated" user_id globally unique?

[reiddavid]

So hopefully quick question... is the signed integer id value located in user_dim.id guaranteed to be unique across instances on the entire Canvas infrastructure?   

(as opposed to say the user_dim.canvas_id which is unique only to a single instance of Canvas)

[ColinMurtaugh]

I'm not sure if user_dim.id is globally unique, but user_dim.global_canvas_id is. 

--Colin