Re: failed to fetch tuple for EvalPlanQual recheck

Excerpts from Andres Freund's message of mar jul 27 17:20:37 -0400 2010:
> On Tue, Jul 27, 2010 at 04:13:56PM -0400, Alvaro Herrera wrote:
> > Excerpts from Kenichiro Tanaka's message of dom jul 25 21:01:01 -0400 2010:
> >
> > > This is a bug report.
> > > When I tested in PostgreSQL9 beta3,I got an error.
> > >
> > > ==================================================
> > > select * from part_bug where HIRENUM=4 for update;
> > > failed to fetch tuple for EvalPlanQual recheck
> > > ==================================================
> > >
> > > Is this error assumed?
> > Hmm, I don't see just an error message here, but an assertion failure:
> I guess youve compiled with --enable-cassert and Kenchiro-san has not?

Eh, of course.  I'm just pointing out that this is a serious bug :-)
I spent some time looking at the code, but the EvalPlanQual stuff is
over my head.  I imagine this is somehow related to the ItemIdSetInvalid
call in ExecLockRows line 97 ('cause that has to do with inheritance
too), but I can't tell.