the wording on the SET TRANSACTION SNAPSHOT left me a bit confused. It says "To begin a new transaction with the same snapshot as an already existing transaction" and it feels like basically taking over an existing session/transaction or being able to replicate a transaction from that snapshot on.
I'm not sure what a final documentation patch might look like but this section can rightfully assume some prior knowledge about how the system works with regards to snapshots. In particular, a snapshot is effectively a single value that a session maintains that lets it compute whether a given transaction id is visible or not. So, "whenever you give me data only do so up to this point-in-time". Understanding that dynamic should lead one to conclude that just having a shared since of "point-in-time" doesn't have anything to do with permissions to interact with specific objects in the first place. And, for temporary tables, to break the session isolation that it is assumed the reader is aware of.
