From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
cc: Stephen Frost <sfrost@snowman.net>,
        Tomas Vondra <tomas.vondra@2ndquadrant.com>,
        Amit Kapila <amit.kapila16@gmail.com>,
        Ian Barwick <ian.barwick@2ndquadrant.com>,
        "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: [PATCH] Stop ALTER SYSTEM from making bad assumptions
In-reply-to: 
 <CA+TgmoYEQyLE8Mtgko9-WSVWm=hLNGi3FO4xNLTrLpwi2GgPHw@mail.gmail.com>
References: <15032.1561403529@sss.pgh.pa.us>
 <20190624192014.GB2480@tamriel.snowman.net>
 <56aff4f3-dec8-f462-7feb-0938411b04a6@2ndquadrant.com>
 <CAA4eK1+JMm=tvx720y6jhD8pdzt=HdS1-TwQwkARib2pwK8EvQ@mail.gmail.com>
 <20190802222254.qsvqjtkwte464lu3@development>
 <31697.1564784856@sss.pgh.pa.us>
 <CAOuzzgqNyQM_z0biEEBVBK9WcaLmbCyWrd5xTdf-Oxb_9pntLA@mail.gmail.com>
 <20190802230011.dqokdhjptykopxxc@development>
 <20190805142139.GW29202@tamriel.snowman.net>
 <CA+Tgmoatso2sR=_LSSR443YjAfvQ48zpbYYVYQUHVMSoxsrJ9g@mail.gmail.com>
 <20190805172935.GK29202@tamriel.snowman.net>
 <CA+TgmoZmSQCta7eN_Y2+U4LthMxcutGB+YXs+0-i6ND2JY0TRA@mail.gmail.com>
 <30179.1565029753@sss.pgh.pa.us>
 <CA+TgmoYEQyLE8Mtgko9-WSVWm=hLNGi3FO4xNLTrLpwi2GgPHw@mail.gmail.com>
Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
	message dated "Mon, 05 Aug 2019 14:38:06 -0400"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <30822.1565030571.1@sss.pgh.pa.us>
Date: Mon, 05 Aug 2019 14:42:51 -0400
Message-ID: <30823.1565030571@sss.pgh.pa.us>
Precedence: bulk

Robert Haas <robertmhaas@gmail.com> writes:
> On Mon, Aug 5, 2019 at 2:29 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I think Stephen is not being unreasonable to suggest that we need some
>> documentation about what external tools may safely do to pg.auto.conf.
>> So somebody's got to write that.

> I mean, really?  We're going to document that if you want to add a
> setting to the file, you can just append it, but that if you find
> yourself desirous of appending so many settings that the entire disk
> will fill up, you should maybe reconsider? Perhaps I'm being mean
> here, but that seems like it's straight out of the
> blinding-flashes-of-the-obvious department.

I don't think we need to go on about it at great length, but it seems
to me that it'd be reasonable to point out that (a) you'd be well
advised not to touch the file while the postmaster is up, and (b)
last setting wins.  Those things are equally true of postgresql.conf
of course, but I don't recall whether they're already documented.

			regards, tom lane