To: Brian McCane <bmccane@mccons.net>
Cc: pgsql-admin <pgsql-admin@postgresql.org>
Subject: Re: VACUUM FULL 
In-reply-to: <20020511173322.J37676-100000@fw.mccons.net> 
References: <20020511173322.J37676-100000@fw.mccons.net>
Comments: In-reply-to Brian McCane <bmccane@mccons.net>
	message dated "Sat, 11 May 2002 17:39:40 -0500"
Date: Sun, 12 May 2002 12:04:50 -0400
Message-ID: <178.1021219490@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Brian McCane <bmccane@mccons.net> writes:
> Okay, now I am a little scared.  Before I started rebuilding indexes, I
> decided to do the VACUUM FULL thing on all of my tables.  On my two most
> referenced tables I am getting:

> ERROR:  No one parent tuple was found

Oh, that's interesting.  We've gotten sporadic reports of that error
message but no one's ever submitted a reproducible case.  Don't suppose
you want to trace through VACUUM FULL with a debugger (or let someone
else do so) to see why it's getting confused?

FWIW, I don't think you need fear data loss.  VACUUM FULL has some, um,
quite baroque code to deal with moving update chains as a unit, and it's
just reporting that it couldn't figure out how to move what looked like
a tuple chain.

AFAIK this situation can only occur when there are open transactions
that can still see some already-replaced tuple.  So the error would
probably go away if you closed all your open transactions.

			regards, tom lane