From: Tom Lane <tgl@sss.pgh.pa.us>
To: Simon Riggs <simon@2ndquadrant.com>
cc: 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.
In-reply-to: <7437.1504634344@sss.pgh.pa.us>
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Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Tue, 05 Sep 2017 13:59:04 -0400"
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Date: Tue, 05 Sep 2017 14:23:03 -0400
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I wrote:
> Huh?  The variable will be set in any case.  It should be correct for any
> server version we might find in the wild --- so far as I can tell from the
> commit history, every version supporting FE/BE protocol version 3 has sent
> server_version at connection start.  With a pre-7.4 server, it looks like
> the variables would be set to "0.0.0" and "0" respectively.

Scratch that: experimentation says it works fine with older servers too.
The oldest one I have in captivity reports

SERVER_VERSION_NAME = '7.0.3'
SERVER_VERSION_NUM = '70003'

Looking more closely, I see that when using protocol version 2, libpq
will issue a "select version()" command at connection start to get
this info.

			regards, tom lane


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