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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
cc: Fabien COELHO <coelho@cri.ensmp.fr>,
        Pavel Stehule <pavel.stehule@gmail.com>,
        Corey Huinker <corey.huinker@gmail.com>,
        Daniel Verite <daniel@manitou-mail.org>,
        PostgreSQL Developers <pgsql-hackers@postgresql.org>
Subject: Re: Variable substitution in psql backtick expansion
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Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
	message dated "Fri, 25 Aug 2017 18:22:03 -0400"
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Date: Fri, 25 Aug 2017 18:43:54 -0400
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Robert Haas <robertmhaas@gmail.com> writes:
> On Fri, Aug 25, 2017 at 6:09 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> ...  I'm still not sure that there's any use case for the
>> string versions ("9.6.4" etc).

> If somebody's doing comparisons, they probably want the numeric
> version, but somebody might want to print the string version in an
> error message e.g. \if <test involving VERSION_NUM> \echo this thing
> doesn't work on :VERSION_NAME \quit \endif

OK, but if human-friendly display is the use-case then it ought to
duplicate what psql itself would print in, eg, the startup message about
server version mismatch.  The v4 patch does not, in particular it neglects
PQparameterStatus(pset.db, "server_version").  This would result in
printing, eg, "11.0" when the user would likely rather see "11devel".

			regards, tom lane


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