From: Tom Lane <tgl@sss.pgh.pa.us>
To: Fabien COELHO <coelho@cri.ensmp.fr>
cc: Simon Riggs <simon@2ndquadrant.com>, Robert Haas <robertmhaas@gmail.com>,
        "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: [COMMITTERS] pgsql: Add psql variables showing server version and
 psql version.
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Comments: In-reply-to Fabien COELHO <coelho@cri.ensmp.fr>
	message dated "Wed, 06 Sep 2017 19:53:40 +0200"
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Date: Wed, 06 Sep 2017 14:37:30 -0400
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Fabien COELHO <coelho@cri.ensmp.fr> writes:
> Thus short, simple but meaningful examples which show how to do something 
> useful with all that in the documentation may help people take advantage 
> of these new features.

I don't have an objection to providing an example.  I wasn't terribly
impressed with Simon's version, but maybe we can do better.  I think
it should be concrete, not partly abstract; and likely it needs to be
with \if not the variable proper.

> Given my experience with "\d*", I'm not sure I would assume that a new 
> psql feature would work with older servers.

I don't recall anyone questioning whether PQserverVersion() would work
with older servers.  Being able to tell what version the server is is
sort of the point, no?  If there were a restriction on what it would
work with, I would agree that that needs to be documented.  But I
don't think "yes, it really works" is a helpful use of documentation
space.

			regards, tom lane


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