To: Alvaro Herrera <alvherre@commandprompt.com>
cc: Chris Browne <cbbrowne@acm.org>, pgsql-patches@postgresql.org
Subject: Re: [DOCS] Autovacuum and XID wraparound 
In-reply-to: <20070515221347.GT12731@alvh.no-ip.org> 
References: <20070514011740.GH14860@fetter.org>
	<23394.1179108400@sss.pgh.pa.us> <1179117269.6047.3.camel@goldbach>
	<60sl9z6tln.fsf@dba2.int.libertyrms.com>
	<20070514221619.GC8916@alvh.no-ip.org>
	<857.1179184222@sss.pgh.pa.us>
	<20070515221347.GT12731@alvh.no-ip.org>
Comments: In-reply-to Alvaro Herrera <alvherre@commandprompt.com>
	message dated "Tue, 15 May 2007 18:13:47 -0400"
Date: Wed, 16 May 2007 01:20:56 -0400
Message-ID: <23362.1179292856@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Alvaro Herrera <alvherre@commandprompt.com> writes:
> Tom Lane wrote:
>> I had the idea we were doing that already --- at least I'm pretty sure I
>> remember it being discussed.  But I see it's not being done in HEAD.

> Patch to do it attached.  I am thinking we can do something similar in
> CLUSTER as well.

Umm ... you'd have to be a lot more conservative in CLUSTER now that
it's MVCC-safe.  I don't say that CLUSTER can't push up relfrozenxid,
but there's something wrong if CLUSTER and TRUNCATE are trying to
push it up the same amount.

			regards, tom lane