From: | Andres Freund <andres(at)2ndquadrant(dot)com> |
---|---|
To: | Stephen Frost <sfrost(at)snowman(dot)net> |
Cc: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: MultiXactId error after upgrade to 9.3.4 |
Date: | 2014-03-31 13:18:07 |
Message-ID: | 20140331131807.GC18358@alap3.anarazel.de |
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Lists: | pgsql-hackers |
On 2014-03-31 09:09:08 -0400, Stephen Frost wrote:
> * Alvaro Herrera (alvherre(at)2ndquadrant(dot)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.
Could you show pg_controldata from the old cluster?
> > 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..
XMAX_IS_INVALID was never allowed to be ignored for vacuum AFAICS. So I
don't think this is a valid explanation.
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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