"PostgreSQL maintains this guarantee even when providing the strictest level of transaction isolation through the use of an innovative Serializable Snapshot Isolation (SSI) level."
Thanks to you both. If other concurrent sessions are using default isolation level of Read committed, would putting long running reports (read-only) into that read-only serializable deferrable mode be impactful at all?
The documentation says that a transaction ID is only assigned to a connection once a write is done, but is the assignment or not of a txn id actually impactful on anything? I ask partly because it doesn't seem possible to reset that once assigned, through discard all; or something else like that which might be used by a connection pooler such as pg bouncer. is there any way to check if a session has "done writes/updates up to this point"? It seems pg_my_temp_schema() also returns the same value even after 'discard temp' or 'discard all' is executed. That was surprising to me, but would it be considered an issue by anyone?
