Date: Fri, 25 Feb 2022 01:15:38 +0800
From: Julien Rouhaud <rjuju123@gmail.com>
To: Jacob Champion <pchampion@vmware.com>
Cc: "michael@paquier.xyz" <michael@paquier.xyz>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>,
	"sfrost@snowman.net" <sfrost@snowman.net>
Subject: Re: [PATCH] Expose port->authn_id to extensions and triggers
Message-ID: <20220224171538.jbf2cxzmhiwuinp4@jrouhaud>
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Hi,

On Thu, Feb 24, 2022 at 04:50:59PM +0000, Jacob Champion wrote:
> On Thu, 2022-02-24 at 20:39 +0900, Michael Paquier wrote:
> > I don't quite see the additional value that this API brings as
> > MyProcPort is directly accessible, and contrib modules like
> > postgres_fdw and sslinfo just use that to find the data of the current
> > backend.
> 
> Right -- I just didn't know if third-party modules were actually able
> to rely on the internal layout of struct Port. Is that guaranteed to
> remain constant for a major release line? If so, this new API is
> superfluous.

Yes, third-party can rely on Port layout.  We don't break ABI between minor
release.  In some occasions we can add additional fields at the end of a
struct, but nothing more.

> > I could still see a use case for that at a more global level with
> > beentrys, but it looked like there was not much interest the last time
> > I dropped this idea.
> 
> I agree that this would be useful to have in the stats. From my outside
> perspective, it seems like it's difficult to get strings of arbitrary
> length in there; is that accurate?

Yes, as it's all in shared memory.  The only workaround is using something like
track_activity_query_size, but it's not great.