| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | "Andrey M(dot) Borodin" <x4mmm(at)yandex-team(dot)ru> |
| Cc: | Mark Dilger <mark(dot)dilger(at)enterprisedb(dot)com>, Amul Sul <sulamul(at)gmail(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Peter Geoghegan <pg(at)bowt(dot)ie>, Andres Freund <andres(at)anarazel(dot)de>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: new heapcheck contrib module |
| Date: | 2020-08-28 19:56:53 |
| Message-ID: | CA+TgmoZo6BHLgZLW5n6ua72GtuMqDieYDhQRpUcFYm9rp-veDQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Aug 28, 2020 at 2:10 PM Andrey M. Borodin <x4mmm(at)yandex-team(dot)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 (while toast 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
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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