Re: new heapcheck contrib module

On Fri, Aug 28, 2020 at 2:10 PM Andrey M. Borodin <x4mmm@yandex-team.ru> wrote:
> I don't think so. ISTM It's the same problem of xmax<relfrozenxid actually, just hidden behind detoasing.
> Our regular heap_check was checking xmin\xmax invariants for tables, but failed to recognise the problem in toast
(whiletoast was accessible until CLOG truncation).
 

The code can (and should, and I think does) refrain from looking up
XIDs that are out of the range thought to be valid -- but how do you
propose that it avoid looking up XIDs that ought to have clog data
associated with them despite being >= relfrozenxid and < nextxid?
TransactionIdDidCommit() does not have a suppress-errors flag, adding
one would be quite invasive, yet we cannot safely perform a
significant number of checks without knowing whether the inserting
transaction committed.

-- 
Robert Haas
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