Re: proposal: schema variables

Some thoughts on this.

On Thu, Nov 2, 2017 at 4:48 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Nico Williams <nico(at)cryptonector(dot)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.
>

I think the basic point one should get here is that no matter the
unification, you still have some things in the db and some things out.

I would rather look at how the GUC could be improved on a functional/use
case level before we look at the question of a technical solution.

One major use case today would be restricting how high various users can
set something like work_mem or the like. As it stands, there isn't really
a way to control this with any granularity. So some of the proposals
regarding granting access to a session variable would be very handy in
granting access to a GUC variable.

>
> Sure, we could have two completely different configuration mechanisms
> so that some of the variables could be "inside the database", but that
> doesn't seem like a net improvement to me. The point of the Grand Unified
> Configuration mechanism was to be unified, after all.
>

+1

>
> I'm on board with having a totally different mechanism for session
> variables. The fact that people have been abusing GUC to store
> user-defined variables doesn't make it a good way to do that.
>

What about having a more clunky syntax as:

SET VARIABLE foo='bar';

Perhaps one can have a short form of:

SET VAR foo = 'bar';

vs

SET foo = 'bar'; -- GUC

>
> regards, tom lane
>
>
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