Re: On login trigger: take three

On 14.09.2020 17:34, Pavel Stehule wrote:

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.

 

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:

psql "dbname=postgres options='-c disable_session_start_trigger=true'"