I am exploring mobile push and need to understand what's happening on a data side. I see this image from contact builder:
This table - mobile push demographics - how does this become populated?
I'm struggling giving that the SDK Documentation states that we should use ContactKey / SubscriberKey, however I don't see this attribute anywhere - and it isn't used to link to all subscribers.
So if i have an externally managed subscriber key - meaning that new subscribers can come into my platform by downloading the app first, and i generate the subscriber key and then push that into the marketing cloud - then this is before they actually have a contact id.
Can someone explain how this process works / should work ?