Re: Adding a pg_servername() function

Hi everybody,

On 09.08.23 08:42, Laetitia Avrot wrote:
> I agree that the feature I'm suggesting could be done with a few tricks.
> I meant to simplify the life of the user by providing a simple new
> feature. (Also, I might have trust issues with DNS due to several past
> production disasters.)

Just my contribution on why this function could be useful, since we had a
use case that fits exactly this.
In the past I needed such a pg_servername() function because in a project I
was engaged on they needed to distribute "requests" directed to a in-house
management service running on network servers, and each one had a DB, so we
went with pglogical to be used as a (transactional) messaging middleware.
The requests were targeted to specific hostnames, thus on the replication
downstream we wanted to filter with a before-insert trigger on the hostname.
At that point, we had to do some contortions to get the hostname the DB was
running on, sometimes really nasty like: on linux servers we could go with
a python function; but on windows ones (where there was no python
available) we had to resort to a function that read the OS "hostname"
command into a temporary table via the pg "copy", which is both tricky and
inefficient.

So, from me +1 to Laetitia's proposal.

On Wed, 9 Aug 2023 at 10:26, Peter Eisentraut <peter(at)eisentraut(dot)org> wrote:

> (*) But we should think about access control for this.

And +1 also to Peter's note on enforcing the access control. BTW that's
exactly what we needed with plpythonu, and also with "copy from program".

Best,
Giovanni