Re: Variable substitution in psql backtick expansion

From: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, Corey Huinker <corey(dot)huinker(at)gmail(dot)com>, Daniel Verite <daniel(at)manitou-mail(dot)org>, PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Variable substitution in psql backtick expansion
Date: 2017-08-26 18:39:36
Message-ID: alpine.DEB.2.20.1708261959560.27500@lancre
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Hello Tom,

> I think you are taking unreasonable shortcuts here:
>
> + SetVariable(pset.vars, "SERVER_VERSION_NAME", PQparameterStatus(pset.db, "server_version"));
>
> The existing code in connection_warnings() does this:
>
> const char *server_version;
>
> /* Try to get full text form, might include "devel" etc */
> server_version = PQparameterStatus(pset.db, "server_version");
> /* Otherwise fall back on pset.sversion */
> if (!server_version)
> {
> formatPGVersionNumber(pset.sversion, true,
> sverbuf, sizeof(sverbuf));
> server_version = sverbuf;
> }
>
> and I think you should duplicate that logic verbatim. Now admittedly,
> server_version has been available for a long time, so that this might
> never matter in practice. But we shouldn't be doing this one way
> in one place and differently somewhere else.

Hmmm. I think this code may have been justified around version 6/7. This
code could probably be removed: according to the online documentation,
"server_version" seems supported at least back to 7.4. Greping old sources
suggest that it is not implemented in 7.3, though.

Spending developer time to write code for the hypothetical someone running
a psql version 11 linked to a libpq < 7.4, if it can even link, does not
look like a very good investment... Anyway, here is required the update.

--
Fabien.

Attachment Content-Type Size
psql-version-num-6.patch text/x-diff 3.4 KB

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