Re: Something flaky in the "relfilenode mapping" infrastructure

On 2014-06-12 00:38:36 -0400, Noah Misch wrote:
> On Tue, Apr 15, 2014 at 03:28:41PM -0400, Tom Lane wrote:
> > Andres Freund <andres@2ndquadrant.com> writes:
> > >> On 2014-03-27 08:02:35 -0400, Tom Lane wrote:
> > >>> Buildfarm member prairiedog thinks there's something unreliable about
> > >>> commit f01d1ae3a104019d6d68aeff85c4816a275130b3:
> > 
> > > So I had made a notice to recheck on
> > > this. http://buildfarm.postgresql.org/cgi-bin/show_history.pl?nm=prairiedog&br=HEAD
> > > indicates there haven't been any further failures... So, for now I
> > > assume this was caused by some problem fixed elsewhere.
> > 
> > Hard to say.  In any case, I agree we can't make any progress unless we
> > see it again.
> 
> The improved test just tripped:

Hrmpf. Just one of these days I was happy thinking it was gone...

> http://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=prairiedog&dt=2014-06-12%2000%3A17%3A07

Hm. My guess it's that it's just a 'harmless' concurrency issue. The
test currently run in concurrency with others: I think what happens is
that the table gets dropped in the other relation after the query has
acquired the mvcc snapshot (used for the pg_class) test.
But why is it triggering on such a 'unusual' system and not on others?
That's what worries me a bit.

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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