Re: VACUUM FULL

Tom,
I was going to do a pg_ctl stop/start cycle to try to fix the
error, however....

What do I need to do to debug? I am on FreeBSD 5.0. I assume I can use
GDB to connect to a running backend, but have not done any serious
debugging in gdb for 4-5 years. If it is too ugly, I might consider
allowing someone into the machine, but it doesn't make me excited to
contemplate it.

- brian

On Sun, 12 May 2002, Tom Lane wrote:

>
> Brian McCane <bmccane(at)mccons(dot)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
>
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