Re: Show dropped users' backends in pg_stat_activity

16.03.2016, 17:48, Tom Lane kirjoitti:
> Robert Haas <robertmhaas@gmail.com> writes:
>> Gee, I would have expected the DROP to be blocked until the user
>> disconnected, like we do for DROP DATABASE.
>
> Making that race-condition-free would require some notion of a lock on
> roles, I think.  Seems pretty messy compared to the amount of actual
> value obtained.  There are good reasons why you can't have a backend
> running in a nonexistent database; but a backend with a nonexistent
> user OID is not really going to be a problem for anything except
> monitoring queries that fail to use left joins where appropriate.

I don't think most people expect dropped users to be able to keep using 
the database.  If it's not feasible to block DROP ROLE until the user 
has disconnected or to kill dropped users' sessions immediately after 
they're dropped we should at least show their sessions in 
pg_stat_activity and add a note about it in DROP ROLE docs.

/ Oskari