| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com>, Mark Dilger <mark(dot)dilger(at)enterprisedb(dot)com>, Masahiko Sawada <masahiko(dot)sawada(at)2ndquadrant(dot)com>, "Andrey M(dot) Borodin" <x4mmm(at)yandex-team(dot)ru>, MBeena Emerson <mbeena(dot)emerson(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Andres Freund <andres(at)anarazel(dot)de>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net> |
| Subject: | Re: recovering from "found xmin ... from before relfrozenxid ..." |
| Date: | 2020-09-21 20:02:29 |
| Message-ID: | CA+TgmoYvurRE7nG4QojQz37zSZ17_QuH4D4zFnFvRvYtqC0xUg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Sep 21, 2020 at 2:21 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Right, but what we end up with is that the very same tuple xmin and
> xmax might result in pruning/deletion, or not, depending on whether
> it's part of a HOT chain or not. That's at best pretty weird, and
> at worst it means that corner-case bugs in other places are triggered
> in only one of the two scenarios ... which is what we have here.
I'm not sure I really understand how that's happening, because surely
HOT chains and non-HOT chains are pruned by the same code, but it
doesn't sound good.
> FWIW, weakening the sanity checks in heap_prepare_freeze_tuple is
> *not* my preferred fix here. But it'll take some work in other
> places to preserve them.
Make sense.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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