To: Robert Haas <robertmhaas@gmail.com>
cc: Fujii Masao <masao.fujii@gmail.com>, Simon Riggs <simon@2ndquadrant.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: [COMMITTERS] pgsql: Efficient transaction-controlled synchronous
	replication.
In-reply-to: <AANLkTinRkoYcfrkMkzFsA3trGfwSxiqLDMw+PA9dicDt@mail.gmail.com> 
References: <E1PwMns-00047O-UU@gemulon.postgresql.org>
	<AANLkTikJmP+bo1N-mFUWEpJiV6_OKisYw512OGeTJUbm@mail.gmail.com>
	<AANLkTinbzFaJXkzwm2xEegfytK1LPw8odo61wgZkkGp=@mail.gmail.com>
	<AANLkTinRkoYcfrkMkzFsA3trGfwSxiqLDMw+PA9dicDt@mail.gmail.com>
Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
	message dated "Fri, 18 Mar 2011 10:10:03 -0400"
Date: Fri, 18 Mar 2011 21:12:52 -0400
Message-ID: <27265.1300497172@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Robert Haas <robertmhaas@gmail.com> writes:
> As a side note, it's not very obvious why some parts of PostmasterMain
> report problems by doing write_stderr() and exit() while other parts
> use ereport(ERROR).  This check and the nearby checks on WAL level are
> immediately preceded and followed by other checks that use the
> opposite technique.

This question is answered in postmaster.c's header comment:

 * Error Reporting:
 *		Use write_stderr() only for reporting "interactive" errors
 *		(essentially, bogus arguments on the command line).  Once the
 *		postmaster is launched, use ereport().	In particular, don't use
 *		write_stderr() for anything that occurs after pmdaemonize.

Code that is involved in GUC variable processing is in a gray area, though,
since it can be invoked both before and after pmdaemonize.  It might be
a good idea to convert all the calls into ereports and maintain a state
flag in elog.c to determine what to do.

			regards, tom lane