Date: Tue, 8 Mar 2011 00:49:56 -0800
From: daveg <daveg@sonic.net>
To: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>,
	Greg Stark <gsstark@mit.edu>
Subject: Re: Re: PD_ALL_VISIBLE flag was incorrectly set happend during
	repeatable vacuum
Message-ID: <20110308084956.GE21941@sonic.net>
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On Tue, Mar 08, 2011 at 10:37:24AM +0200, Heikki Linnakangas wrote:
> On 08.03.2011 10:00, Heikki Linnakangas wrote:
> >Another idea is to give up on the warning when it appears that
> >oldestxmin has moved backwards, and assume that it's actually fine. We
> >could still warn in other cases where the flag appears to be incorrectly
> >set, like if there is a deleted tuple on the page.
> 
> This is probably a better idea at least in back-branches. It also 
> handles the case of twiddling vacuum_defer_cleanup_age, which tracking 
> two xmins per transactions would not handle.
> 
> Here's a patch. I also changed the warning per Robert's suggestion. 
> Anyone see a hole in this?

It would be helpful to have the dbname and schema in the message in addition
to the relname. I added those to the original diagnostic patch as it was not
clear that the messages were all related to the same page/table/dg.

Also, in your comment you might mention that multiple databases are one way
we could see oldestxmin move backwards.

-dg
 

-- 
David Gould       daveg@sonic.net      510 536 1443    510 282 0869
If simplicity worked, the world would be overrun with insects.