Date: Mon, 31 Mar 2014 09:09:08 -0400
From: Stephen Frost <sfrost@snowman.net>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Andres Freund <andres@2ndquadrant.com>, pgsql-hackers@postgresql.org
Subject: Re: MultiXactId error after upgrade to 9.3.4
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* Alvaro Herrera (alvherre@2ndquadrant.com) wrote:
> I guess I wasn't expecting that too-old values would last longer than a
> full wraparound cycle.  Maybe the right fix is just to have the second
> check also conditional on allow_old.

I don't believe this was a wraparound case.

> Anyway, it's not clear to me why this database has a multixact value of
> 6 million when the next multixact value is barely above one million.
> Stephen said a wraparound here is not likely.

I don't think the xmax value is a multixact at all- I think it's
actually a regular xid, but everyone is expected to ignore it because
XMAX_IS_INVALID, yet somehow the MULTIXACT bit was also set and the new
code expects to be able to look at the xmax field even though it's
marked as invalid..

I'm going through the upgrade process again from 9.2 and will get a
stack trace.

	Thanks,

		Stephen

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