Re: Variable substitution in psql backtick expansion

Fabien COELHO <coelho@cri.ensmp.fr>

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: 2017-04-02T07:45:52Z

Lists: pgsql-hackers

Attachments

psql-version-num-1.patch (text/x-diff) patch

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?

-- 
Fabien.

Commits

Add psql variables showing server version and psql version.
- a6c678f018d3 10.0 landed
- 9ae9d8c1549c 11.0 landed
Reformat psql's --help=variables output.
- 3955c8c4eda2 11.0 landed
Remove reinvention of stringify macro.
- cd6baed78150 10.0 landed
Allow psql variable substitution to occur in backtick command strings.
- f833c847b8fa 10.0 landed