Date: Thu, 2 Nov 2017 13:52:39 -0500
From: Nico Williams <nico@cryptonector.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>,
	Pavel Stehule <pavel.stehule@gmail.com>,
	PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Subject: Re: proposal: schema variables
Message-ID: <20171102185237.GQ4496@localhost>
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On Thu, Nov 02, 2017 at 11:48:44AM -0400, Tom Lane wrote:
> Nico Williams <nico@cryptonector.com> writes:
> > With access controls, GUCs could become schema variables, and settings
> > from postgresql.conf could move into the database itself (which I think
> > would be nice).
> 
> People re-propose some variant of that every so often, but it never works,
> because it ignores the fact that some of the GUCs' values are needed
> before you can access system catalogs at all, or in places where relying
> on system catalog access would be a bad idea.

ISTM that it should be possible to break the chicken-egg issue by having
the config variables stored in such a way that knowing only the pgdata
directory path should suffice to find them.  That's effectively the case
already in that postgresql.conf is found... there.

One could do probably this as a PoC entirely as a SQL-coded VIEW that
reads and writes (via the adminpack module's pg_catalog.pg_file_write())
postgresql.conf (without preserving comments, or with some rules
regarding comments so that they are effectively attached to params).

Nico
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