Re: Adding a pg_servername() function

Le jeu. 3 août 2023 à 15:17, Christoph Moench-Tegeder <cmt(at)burggraben(dot)net>
a écrit :

> ## Laetitia Avrot (laetitia(dot)avrot(at)gmail(dot)com):
>

> > For my customer, their use case is to be able from an SQL client to
> double
> > check they're on the right host before doing things that could become a
> > production disaster.
>
> Why not use cluster_name for that? Even if it may not be relevant
> for their setup, there might be multiple clusters on the same host
> (multiple clusters with the same hostname) or you database could be
> hiding behind some failover/loadbalancer mechanism (multiple hostnames
> in one cluster), thus using the hostname to identify the cluster is
> totally not universal (the same goes for the monitoring/metrics
> stuff). And there's of course inet_server_addr(), if you really
> need to double-check if you're connected to the right machine.
>

Hello Christoph,

I understand your point and sure enough, my customer could set and use the
cluster_name for that purpose. I totally disagree with using
inet_server_addr() for that purpose as there are so many different network
settings with VIPs and so on that it won't help. Also, a socket connection
will give a NULL value, not that it's *that* bad because if it's a socket,
you're running locally and could still use `\! ifconfig`, but it does not
work on some configurations (docker for example). Also, most humans will
find it easier to memorize a name than a number and that's one of the
reasons why we remember websites' URLs instead of their IP.

I still disagree with the monitoring part. A good monitoring tool will have
to reconcile data from the OS with data from the Postgres cluster. So that,
we kind of need a way for the monitoring tool to know on which host this
particular cluster is running and I think it's smarter to get this
information from the Postgres cluster.

Of course, I do love the idea that Postgres is agnostic from where it's
running, but I don't think this new function removes that.

Have a nice day,

Lætitia