Re: ALTER SYSTEM SET command to change postgresql.conf parameters (RE: Proposal for Allow postgresql.conf values to be changed via SQL [review])

* Alvaro Herrera (alvherre@2ndquadrant.com) wrote:
> Amit Kapila escribió:
> >    3. postgresql.conf will contain include directive in below form:
> >        #include = 'postgresql.auto.conf'
> >        Whenever user wants to use Alter System, he needs to enable it
> > after first time using ALTER SYSTEM.
>
> This seems wrong to me.  If the auto file is read by an include line in
> postgresql.conf, what is its priority w.r.t. files placed in an
> hypothetical conf.d directory?

This could be handled by a simple ordering with "last one wins".  I
don't particularly like that though..  My gut feeling is that I'd like
something to complain if there's more than one value set for the same
GUC..

> Hopefully snippets put in conf.d/ by
> puppet/chef will override the settings in postgresql.conf (i.e. conf.d/
> should be processed after postgresql.conf, not before); and hopefully
> ALTER SYSTEM will in turn override conf.d.  I see no way to have ALTER
> SYSTEM handled by an include line, yet still have it override conf.d.

With includedir and include directives, and postgresql.conf setting a
defined ordering, with last-wins, you could simply have the 'includedir'
for conf.d come before the 'include' for auto.conf.

> If we want to make ALTER SYSTEM disable-able from postgresql.conf, I
> think it should be an explicit option, something like
> enable_alter_system = on
> or something like that.

I really don't like this approach- I'd much rather we have a general
include mechanism than special "alter-system" GUCs.
Thanks,
    Stephen