Re: PostgreSQL 8.1.0 catalog corruption

From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Bob Ippolito <bob(at)redivi(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: PostgreSQL 8.1.0 catalog corruption
Date: 2005-11-22 00:33:16
Message-ID: 20051122003316.GC1305@surnet.cl
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Tom Lane wrote:
> Bob Ippolito <bob(at)redivi(dot)com> writes:
> > On Nov 21, 2005, at 3:56 PM, Tom Lane wrote:
> >> Well, I count at least a couple hundred deleted versions of that table
> >> row :-(. What the heck were you doing with it?
>
> > The ETL process keeps trying until it succeeds or someone stops it,
> > so I guess that's why there's so much churn in there for that table.
> > Kept trying to create it, and ran into the issue. I'd estimate
> > around 1700 to 1800 dead versions of that table, because it ran for
> > some time before I noticed and stopped it... this is just a test box
> > after all, I don't have 8.1 in production yet (thankfully!).
>
> Um, no, that theory doesn't seem to explain the evidence. A failed
> insertion would result in a row with an uncommitted XMIN and no XMAX.
> All of the entries I'm seeing have both XMIN and XMAX set. A good-size
> fraction have the same XMIN and XMAX (but different CMIN and CMAX), but
> I see some that have different XMIN and XMAX. It looks to me like the
> table was definitely created successfully, and it survived across
> multiple transactions ... but something was doing a lot of DDL changes
> on it. If we could find out what, maybe we could reproduce the problem.

Maybe the UPDATE pg_class SET relhastriggers='f' that people is so fond
of doing to deactivate triggers? Or something similar?

--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.

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