Horton

Re: Variable substitution in psql backtick expansion

Fabien COELHO <coelho@cri.ensmp.fr>

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From: Fabien COELHO <coelho@cri.ensmp.fr>
To: Pavel Stehule <pavel.stehule@gmail.com>
Cc: Daniel Verite <daniel@manitou-mail.org>, Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL Developers <pgsql-hackers@postgresql.org>
Date: 2017-04-02T11:13:47Z
Lists: pgsql-hackers 
Hello Pavel,

>>   \echo :VERSION
>>   PostgreSQL 10devel on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu
>> 5.4.0-6ubuntu1~16.04.4) 5.4.0 20160609, 64-bit
>>
>> Probably some :VERSION_NUM would make some sense. See attached PoC patch.
>> Would it make sense?
>
> Maybe better name for you CLIENT_VERSION_NUM

If it was starting from nothing I would tend to agree with you, but there 
is already an existing :VERSION variable, so it seemed logical to keep on 
and create variants with the same prefix.

> Can be SERVER_VERSION_NUM taken from connection info?

Probably it could. It seems a little less straightforward than defining a 
client-side string at compile time. The information is displayed when the 
connection is established, so the information is there somewhere.

  psql (10devel, server 9.6.2)

-- 
Fabien.

Commits

  1. Add psql variables showing server version and psql version.

  2. Reformat psql's --help=variables output.

  3. Remove reinvention of stringify macro.

  4. Allow psql variable substitution to occur in backtick command strings.