Greetings,
* Adam Sjøgren (asjo@koldfront.dk) wrote:
> We have a PostgreSQL 11.3¹ running on an Ubuntu 16.04 server, which
> sometimes exhibits a behaviour I can't quite understand: simply logging
> into the database starts to take minutes to complete.
>
> We have 60 processes (workers) running on different machines accessing
> the database, that all grab jobs from a queue and update rows in a table
> after doing some calculations (which vary in time from <1s to perhaps a
> minute, many of them fast).
>
> Sometimes new database logins slow down, from usually taking <0.05s to
> taking minutes. This is for psql as a normal user using Kerberos, for
> psql as the postgres superuser, for the web-application logging into the
> database, for everything.
When in doubt, blame DNS.
Alternatively, in your case, the issue might be the KDC taking forever
to issue a ticket for the service.
Note that, in both cases, this is a client-side issue. Once the ticket
has been acquired for the PG service, the actual authentication on the
server side should be very fast and not depend on things external
(though you might check if you have log_hostnames on..).
Thanks,
Stephen