Re: [COMMITTERS] pgsql: Fix freezing of a dead HOT-updated tuple

Michael Paquier wrote:
> On Sun, Oct 1, 2017 at 10:25 AM, Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> > On Thu, Sep 28, 2017 at 1:20 PM, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
> >> Maybe what this means is that we need to do both Dan's initially
> >> proposed patch (or something related to it) apart from the fixes already
> >> pushed. IOW we need to put back some of the "tupkeep" business ...
> >
> > I took the time to specifically check if that would fix the problem.
> > Unfortunately, it did not. We see exactly the same problem, or at
> > least amcheck/REINDEX produces exactly the same error. I checked both
> > Dan's original update_freeze.patch, and your revision that retained
> > some of the "tupkeep" stuff,
> > 0002-Don-t-freeze-recently-dead-HOT-tuples, which you posted on
> > September 6th.
>
> I did not take the time to dig into that more than two hours, but my
> first feeling is that some race condition is going on with the heap
> pruning.

I'll look into this on Monday. I found out yesterday that the
problematic case is when HTSV returns HEAPTUPLE_DEAD and the HOT tests
return true. I haven't yet figured if it is one of those specifically,
but I suspect it is the IsHotUpdated case.

--
Álvaro Herrera https://www.2ndQuadrant.com/
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