Date: Fri, 21 Jun 2019 12:40:28 -0400
From: Stephen Frost <sfrost@snowman.net>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>,
	Ian Barwick <ian.barwick@2ndquadrant.com>,
	Amit Kapila <amit.kapila16@gmail.com>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: [PATCH] Stop ALTER SYSTEM from making bad assumptions
Message-ID: <20190621164028.GO2480@tamriel.snowman.net>
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Greetings,

* Tom Lane (tgl@sss.pgh.pa.us) wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
> > To me, forcing every tools author to use postgresql.conf parsing tools
> > rather than just appending to the file is a needless burden on tool
> > authors.  I'd vote for just having ALTER SYSTEM silently drop all but
> > the last of duplicated entries.
>=20
> I haven't been paying too close attention to this thread, but isn't
> that exactly what it does now and always has?  guc.c, at least, certainly
> is going to interpret duplicate entries that way.

The issue isn't with reading them and interpreting them, it's what
happens when you run ALTER SYSTEM and it goes and modifies the file.
Presently, it basically operates on the first entry it finds when
performing a SET or a RESET.

Which also means that you can issue SET's to your heart's content, and
if there's a duplicate for that GUC, you'll never actually change what
is interpreted.

Thanks,

Stephen

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