On 03/21/2018 11:15 AM, Albrecht Dreß wrote:
> Hi Adrian & Tom:
>
> Thanks a lot for your input!
>
> Am 20.03.18 20:38 schrieb(en) Tom Lane:
See comments inline below.
>
> Unfortunately, in my original post, I confused the primary and secondary
> (accessed via the FDW) data bases in my example when I anonymised their
> identifiers… Sorry for the confusion! The /real/ structure is
>
> client ---[libpq]--> my_db ---[FDW]--> ext_db
>
> and the LOG message is actually related to the “internal” connection,
> i.e. ext_db (*not* my_db) complains about “could not receive data” after
> accessing the table in ext_db through the FDW from my_db.
>
> The effect is not limited to Python, but happens with psql, too. I.e.
> running (ext_table is the foreign table mapped into my_db, and a mapping
> exists only for user “user”)
>
> sudo -u user /usr/lib/postgresql/10/bin/psql my_db <<< "select * from
> ext_table limit 1;"
>
> *also* triggers the LOG message
Does it also happen when you open a psql session and do?:
psql>select * from ext_table limit 1;
>
> [time stamp/pid] user@ext_db LOG: could not receive data from client:
> Connection reset by peer
>
>> I don't see any such log messages when testing postgres_fdw here,
>> which is odd; why are my results different?
>
> Yes, that's strange! I have the following deb packages (from the
> stretch-pgdg repo) installed:
>
> postgresql-10 10.3-1.pgdg90+1 amd64
> postgresql-client-10 10.3-1.pgdg90+1 amd64
> postgresql-client-common 190.pgdg90+1 all
> postgresql-common 190.pgdg90+1 all
> libpq5:amd64 10.3-1.pgdg90+1 amd64
I am not seeing --contrib which is where I would expect postgres_fdw to
come from.
Is --contrib installed?
If not where is postgres_fdw coming from?
>
>> If these are about the FDW connections, maybe the answer is that
>> postgres_fdw ought to establish a backend-exit callback in which it
>> can shut down its connections gracefully.
>
> Hmm, yes, sounds like a sensible explanation.
>
>> If it's doing that now, I sure don't see where.
>
> So, if I understand you correctly, this needs to be addressed in
> postgres_fdw, and there is nothing I can fix in my setup (except for
> suppressing LOG messages) to get rid of the message?
>
> Thanks again,
> Albrecht.
--
Adrian Klaver
adrian.klaver@aklaver.com
