Horton

Re: [HACKERS] Re: PD_ALL_VISIBLE flag was incorrectly set happend during repeatable vacuum

Maxim Boguk <maxim.boguk@gmail.com>

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From: Maxim Boguk <maxim.boguk@gmail.com>
To: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: daveg <daveg@sonic.net>, Fujii Masao <masao.fujii@gmail.com>, pgsql-admin@postgresql.org, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2011-03-01T21:44:11Z
Lists: pgsql-hackers

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  1. Fix a violation of WAL coding rules in the recent patch to include an

Hi

On Tue, Mar 1, 2011 at 11:00 AM, Heikki Linnakangas <
heikki.linnakangas@enterprisedb.com> wrote:

> 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
>


Sorry, I was a bit busy lately.
This effect on my production servers seems have floating nature (some weeks
it happen each day many time and some weeks - not at all... phase of the
moon may be). Last 2 weeks I don't see that error in database logs so I
can't add anything more.

What make situation even harder to debug it is I can't compile and install
patched version of database engine (because it is production server and I
physically don't have access to changing software there). So I trying to
reproduce error on single connect  (so I can attach GDB and look inside) but
without luck during last week.

-- 
Maxim Boguk
Senior Postgresql DBA.

Skype: maxim.boguk
Jabber: maxim.boguk@gmail.com

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If they can send one man to the moon... why can't they send them all?

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