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Re: Bug: Unreferenced temp tables disables vacuum to update xid

From: "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
To: Bruce Momjian <bruce(at)momjian(dot)us>
Cc: Alvaro Herrera <alvherre(at)commandprompt(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Bug: Unreferenced temp tables disables vacuum to update xid
Date: 2008-01-07 17:10:24
Message-ID: 20080107091024.6f403cde@commandprompt.com (view raw or flat)
Thread:
Lists: pgsql-hackers
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On Mon, 7 Jan 2008 11:58:29 -0500 (EST)
Bruce Momjian <bruce(at)momjian(dot)us> wrote:

> > > Ah -- interesting.  This is a known issue, but we haven't found a
> > > solution yet.
> > > 
> > 
> > Is there bug number?
> 
> I assume it is this TODO item:
> 
>         o Prevent long-lived temporary tables from causing frozen-xid
>           advancement starvation
> 
>           The problem is that autovacuum cannot vacuum them to set
> frozen xids; only the session that created them can do that.
>           http://archives.postgresql.org/pgsql-general/2007-06/msg01645.php
> 
> but am confused how the fix worked.  Have all of these backends been
> active for 1 billion transactions?

Well it certainly appears that the TODO item is related. However there
are a couple of differences.

1. I had to manually vacuum because we had already hid xidStoplimit.

2. Postgres has been restarted multiple times and it made zero
difference.

E.g; PostgreSQL isn't cleaning up after itself and it isn't apparent
when it happens. 

Sincerely,

Joshua D. Drake
 


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Subject: Re: VACUUM FULL out of memory
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