Horton

Re: Variable substitution in psql backtick expansion

Pavel Stehule <pavel.stehule@gmail.com>

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From: Pavel Stehule <pavel.stehule@gmail.com>
To: Fabien COELHO <coelho@cri.ensmp.fr>
Cc: Daniel Verite <daniel@manitou-mail.org>, Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL Developers <pgsql-hackers@postgresql.org>
Date: 2017-04-02T10:08:56Z
Lists: pgsql-hackers 
2017-04-02 9:45 GMT+02:00 Fabien COELHO <coelho@cri.ensmp.fr>:

>
> Hello Pavel,
>
> For this case can be nice to have function that returns server version as
>> number some like version_num() .. 10000
>>
>
> The server side information can be queried:
>
>   SELECT current_setting(‘server_version_num’)
>     AS server_version_num \gset
>   -- 90602
>
> However client side is not so clean:
>
>   \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?


It has sense

Pavel

>
>
> --
> 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.