| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Jonathan S(dot) Katz" <jkatz(at)postgresql(dot)org>, Andres Freund <andres(at)anarazel(dot)de>, Noah Misch <noah(at)leadboat(dot)com>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Bruce Momjian <bruce(at)momjian(dot)us>, Michael Paquier <michael(at)paquier(dot)xyz>, Justin Pryzby <pryzby(at)telsasoft(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, Shruthi Gowda <gowdashru(at)gmail(dot)com> |
| Subject: | Re: pg15b2: large objects lost on upgrade |
| Date: | 2022-08-04 18:04:14 |
| Message-ID: | CAH2-Wzk9vFnvhvQSGbsY8UUQp-TCGAXea=GohGLJ6d_93PuKFg@mail.gmail.com |
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On Thu, Aug 4, 2022 at 9:44 AM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> But if you don't want to do that, and you also don't want to have
> random failures, the only alternatives are weakening the check and
> removing the test. It's kind of hard to say which is better, but I'm
> inclined to think that if we just weaken the test we're going to think
> we've got coverage for this kind of problem when we really don't.
Perhaps amcheck's verify_heapam() function can be used here. What
could be better than exhaustively verifying that the relfrozenxid (and
relminmxid) invariants hold for every single tuple in the table? Those
are the exact conditions that we care about, as far as
relfrozenxid/relminmxid goes.
My sense is that that has a much better chance of detecting a real bug
at some point. This approach is arguably an example of property-based
testing.
--
Peter Geoghegan
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