If we introduce buildin session trigger , we should to define what is the session. Your design is much more related to the process than to session. So the correct name should be "process_start" trigger, or some should be different. I think there are two different events - process_start, and session_start, and there should be two different event triggers. Maybe the name "session_start" is just ambiguous and should be used with a different name.
I agree. I can rename trigger to backend_start or process_start or whatever else.
Creating a good name can be hard - it is not called for any process - so maybe "user_backend_start" ?
5. I do not quite understand your concern. If I define trigger procedure which is blocked (for example as in your example), then I can use pg_cancel_backend to interrupt execution of login trigger and superuser can login. What should be changed here?
You cannot run pg_cancel_backend, because you cannot open a new session. There is a cycle.
It is always possible to login by disabling startup triggers using disable_session_start_trigger GUC:
sure, I know. Just this behavior can be a very unpleasant surprise, and my question is if it can be fixed. Creating custom libpq variables can be the stop for people that use pgAdmin.
