in my defined flow, a user gets a user_id after they sign up to the system.
Before the user signs up and gets his user_id, I can view all his events by looking at amplitude_id.
After the user signs up, I can view all his events by looking at user_id.
my issue is that I am exporting all of Amplitude data to BigQuery, and I want to “merge” that user’s events (pre-sign up and after signup events) and can not find what is there that “unites” them.
it's like all the user's properties are changing after he gets his user_id.
The user stream on amplitude shows the full user journey (pre-sign up and after signup events), and I want to be able to do the same in my BQ.