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@xxxxxxxxxxx
