| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Removing more vacuumlazy.c special cases, relfrozenxid optimizations |
| Date: | 2022-02-20 03:18:25 |
| Message-ID: | CAH2-WzkUXpAMKpytrRUtPkfQSXznaas3EyEsh7rLUrhsCqzuQw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Sat, Feb 19, 2022 at 7:01 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> It's kind of surprising that this needs this
> 0001-Add-adversarial-ConditionalLockBuff to break. I suspect it's a question
> of hint bits changing due to lazy_scan_noprune(), which then makes
> HeapTupleHeaderIsHotUpdated() have a different return value, preventing the
> "If the tuple is DEAD and doesn't chain to anything else"
> path from being taken.
That makes sense as an explanation. Goes to show just how fragile the
"DEAD and doesn't chain to anything else" logic at the top of
heap_prune_chain really is.
--
Peter Geoghegan
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