Re: [DOCS] HOT - correct claim about indexes not referencing old line pointers

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: James Coleman <jtc331(at)gmail(dot)com>
Cc: Peter Geoghegan <pg(at)bowt(dot)ie>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Bruce Momjian <bruce(at)momjian(dot)us>, Melanie Plageman <melanieplageman(at)gmail(dot)com>
Subject: Re: [DOCS] HOT - correct claim about indexes not referencing old line pointers
Date: 2024-03-14 14:27:54
Message-ID: CA+TgmobyiHDzrv2dscy7HgjVw_NNenUpKnDPv8LeGO+XxsNe1Q@mail.gmail.com
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On Wed, Oct 4, 2023 at 9:12 PM James Coleman <jtc331(at)gmail(dot)com> wrote:
> All right, attached is a v3 which attempts to fix the wrong
> information with an economy of words. I may at some point submit a
> separate patch that adds a broader pruning section, but this at least
> brings the docs inline with reality insofar as they address it.

I don't think this is as good as what I proposed back on October 2nd.
IMHO, that version does a good job making the text accurate and clear,
and is directly responsive to your original complaint, namely, that
the root of the HOT chain can't be removed. But this version seems to
contain a number of incidental changes that are unrelated to that
point, e.g. "old versions" -> "old, no longer visible versions", "can
be completely removed" -> "may be pruned", and the removal of the
sentence "In summary, heap-only tuple updates can only be created - if
columns used by indexes are not updated" which AFAICT is both
completely correct as-is and unrelated to the original complaint.

Maybe I shouldn't be, but I'm slightly frustrated here. I thought I
had proposed an alternative which you found acceptable, but then you
proposed several more versions that did other things instead, and I
never really understood why we couldn't just adopt the version that
you seemed to think was OK. If there's a problem with that, say what
it is. If there's not, let's do that and move on.

--
Robert Haas
EDB: http://www.enterprisedb.com

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