Date: Tue, 12 Apr 2022 12:49:38 -0700
From: Nathan Bossart <nathandbossart@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Julien Rouhaud <rjuju123@gmail.com>,
	Michael Paquier <michael@paquier.xyz>,
	"Bossart, Nathan" <bossartn@amazon.com>,
	Fujii Masao <masao.fujii@oss.nttdata.com>,
	"wangsh.fnst@fujitsu.com" <wangsh.fnst@fujitsu.com>,
	Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>,
	Greg Sabino Mullane <htamfids@gmail.com>,
	Tom Lane <tgl@sss.pgh.pa.us>,
	"pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Subject: Re: make MaxBackends available in _PG_init
Message-ID: <20220412194938.GA2064338@nathanxps13>
References: <20220330163051.GA784643@nathanxps13>
 <YlGJGiofZiWN3elx@jrouhaud>
 <CA+TgmoZRnwF=9tMX0TiqZGC4qAK_27NweKd5r-S=OSaE_nL70A@mail.gmail.com>
 <20220411164408.GA1915258@nathanxps13>
 <CA+TgmoZVQznhWpUr-bjC9U=Won8ZnfozSkiXrW2HU80r6QyASQ@mail.gmail.com>
 <20220411204442.GA2004824@nathanxps13>
 <20220411211435.GA2057981@nathanxps13>
 <20220412174427.sngj2uexzsttazs2@alap3.anarazel.de>
 <20220412180306.GA2063516@nathanxps13>
 <CA+TgmoY4og1VADa78VySwsTjtTQbtXbnRPSq9x=e6ogS_wWfaw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: 
 <CA+TgmoY4og1VADa78VySwsTjtTQbtXbnRPSq9x=e6ogS_wWfaw@mail.gmail.com>
Archived-At: 
 <https://www.postgresql.org/message-id/20220412194938.GA2064338%40nathanxps13>
Precedence: bulk

On Tue, Apr 12, 2022 at 03:12:42PM -0400, Robert Haas wrote:
> But if there's even one use case where adjusting GUCs at this phase is
> reasonable, then 0003 isn't really good enough. We need an 0004 that
> provides a new hook in a place where such changes can safely be made.

I think that is doable.  IMO it should be ѕomething like _PG_change_GUCs()
that is called before _PG_init().  The other option is to add a hook called
after _PG_init() where MaxBackends is available (in which case we likely
want GetMaxBackends() again).  Thoughts?

> Meanwhile, committed 0001.

Thanks.

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com