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Message-ID: <4D6C1B16.6030708@enterprisedb.com>
Date: Tue, 01 Mar 2011 00:00:54 +0200
From: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
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To: daveg <daveg@sonic.net>
CC: Maxim Boguk <maxim.boguk@gmail.com>, Fujii Masao <masao.fujii@gmail.com>,
	pgsql-admin@postgresql.org,
	PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: [HACKERS] Re: PD_ALL_VISIBLE flag was incorrectly set
	happend during repeatable vacuum
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On 28.02.2011 23:28, daveg wrote:
> On Wed, Jan 12, 2011 at 10:46:14AM +0200, Heikki Linnakangas wrote:
>> We'll likely need to go back and forth a few times with various
>> debugging patches until we get to the heart of this..
>
> Anything new on this? I'm seeing at on one of my clients production boxes.

I haven't heard anything from the OP since.

> Also, what is the significance, ie what is the risk or damage potential if
> this flag is set incorrectly?

Sequential scans will honor the flag, so you might see some dead rows 
incorrectly returned by a sequential scan. That's the only "damage", but 
an incorrectly set flag could be a sign of something more sinister, like 
corrupt tuple headers. The flag should never be set incorrectly, so if 
you see that message you have hit a bug in PostgreSQL, or you have bad 
hardware.

This flag is quite new, so a bug in PostgreSQL is quite possible. If you 
still have a backup that contains those incorrectly set flags, I'd like 
to see what the page looks like.

-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com