Horton

Re: On login trigger: take three

Pavel Stehule <pavel.stehule@gmail.com>

View thread View on postgr.es
From: Pavel Stehule <pavel.stehule@gmail.com>
To: Konstantin Knizhnik <k.knizhnik@postgrespro.ru>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2020-09-14T16:11:46Z
Lists: pgsql-hackers 
po 14. 9. 2020 v 17:53 odesílatel Konstantin Knizhnik <
k.knizhnik@postgrespro.ru> napsal:

>
>
> 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.
>

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

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.

Commits

  1. Fix some typos in event trigger docs

  2. Use heap_inplace_update() to unset pg_database.dathasloginevt

  3. Remove the flaky check in event_trigger_login regression test

  4. Fix instable 006_login_trigger.pl test

  5. Add support event triggers on authenticated login

  6. Add GUC for temporarily disabling event triggers

  7. Fix typo in reference to __FreeBSD__.

  8. Restore robustness of TAP tests that wait for postmaster restart.

  9. Restore the portal-level snapshot after procedure COMMIT/ROLLBACK.