Horton

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

Stephen Frost <sfrost@snowman.net>

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From: Stephen Frost <sfrost@snowman.net>
To: Bruce Momjian <bruce@momjian.us>
Cc: Amit Kapila <amit.kapila16@gmail.com>, Martijn van Oosterhout <kleptog@svana.org>, Alvaro Herrera <alvherre@2ndquadrant.com>, Robert Haas <robertmhaas@gmail.com>, Dimitri Fontaine <dimitri@2ndquadrant.fr>, Andres Freund <andres@2ndquadrant.com>, Josh Berkus <josh@agliodbs.com>, Tom Lane <tgl@sss.pgh.pa.us>, Fujii Masao <masao.fujii@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2013-08-28T18:30:41Z
Lists: pgsql-hackers 
* Bruce Momjian (bruce@momjian.us) wrote:
> On Tue, Aug 27, 2013 at 09:04:00AM +0530, Amit Kapila wrote:
> > > I really hate the idea that someone could configure 'X' in
> > > postgresql.conf and because the auto.conf line is later in the file,
> > > it's able to override the original setting.  Does not strike me as
> > > intuitive at all.
> > 
> > This is currently how include mechanism works in postgresql.conf,
> > changing that for this special case can be costly and moreover the
> > specs for this patch were layout from beginning that way.
> 
> Agreed.  If you are worried about ALTER SYSTEM changing postgresql.conf
> settings, you should move the include_auto line to the top of
> postgresql.conf, but I don't think that should be the default.

While I appreciate that there are bootstrap-type issues with this, I
really don't like this idea of "later stuff can just override earlier
stuff".

include files and conf.d-style options are for breaking the config up,
not to allow you to override options because a file came later than an
earlier file.  Our particular implementation of config-file reading
happens to lend itself to later-definition-wins, but that's really
counter-intuitive for anyone unfamiliar with PG, imv.

	Thanks,

		Stephen