Message-ID: <4CC0E465.4000700@agliodbs.com>
Date: Thu, 21 Oct 2010 18:09:57 -0700
From: Josh Berkus <josh@agliodbs.com>
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US;
	rv:1.9.1b3pre) Gecko/20090223 Thunderbird/3.0b2
MIME-Version: 1.0
To: Bruce Momjian <bruce@momjian.us>
CC: Robert Haas <robertmhaas@gmail.com>, Greg Stark <gsstark@mit.edu>,
	pgsql-hackers@postgresql.org
Subject: Re: Simplifying replication
References: <201010220058.o9M0waa06053@momjian.us>
In-Reply-To: <201010220058.o9M0waa06053@momjian.us>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit


>> Very true.  But the lack of a -1 setting for wal_keep_segments means
>> that if you would like to take a backup without archiving, you must
>> set wal_keep_segments to a value greater than or equal to the rate at
>> which you generate WAL segments multiplied by the time it takes you to
>> run a backup.  If that doesn't qualify as requiring arcane knowledge,
>> I'm mystified as to what ever could.

Speaking of which, what's the relationship between checkpoint_segments
and wal_keep_segments?  PG seems perfectly willing to let me set the
latter higher than the former, and it's not documented.

If checkpoint_segments were a hard limit, then we could let admins set
wal_keep_segments to -1, knowing that they'd set checkpoint_segments to
the max space they had available.

Although we might want to rename those.

-- 
                                  -- Josh Berkus
                                     PostgreSQL Experts Inc.
                                     http://www.pgexperts.com