| From: | David Rowley <dgrowleyml(at)gmail(dot)com> |
|---|---|
| To: | Amit Langote <amitlangote09(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Ashutosh Bapat <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com>, Yuya Watari <watari(dot)yuya(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, Dmitry Dolgov <9erthalion6(at)gmail(dot)com>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, jian he <jian(dot)universality(at)gmail(dot)com>, Alena Rybakina <lena(dot)ribackina(at)yandex(dot)ru>, Andrei Lepikhov <a(dot)lepikhov(at)postgrespro(dot)ru>, Thom Brown <thom(at)linux(dot)com>, Zhang Mingli <zmlpostgres(at)gmail(dot)com> |
| Subject: | Re: [PoC] Reducing planning time when tables have many partitions |
| Date: | 2025-04-10 03:03:02 |
| Message-ID: | CAApHDvpXEF+T_AUkLmF8=9O0+ruHjnBjjLf9A2oCqZSHgnp0Ug@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, 9 Apr 2025 at 17:38, Amit Langote <amitlangote09(at)gmail(dot)com> wrote:
> Still, maybe a tiny tweak to the last line could help steer readers
> right without diving into storage. How about:
>
> Most operations on EquivalenceClasses should ignore child members,
> which are stored separately from normal members.
I think the only part of the current text that makes me slightly
uncomfortable is the "ignore child members". I don't mind your text,
but it does introduce detail about how the members are stored, which
isn't there before.
I think the "ignore child members" part could be fixed with:
--- a/src/backend/optimizer/README
+++ b/src/backend/optimizer/README
@@ -902,7 +902,7 @@ contain the equivalent child-relation variables or
expressions. These
members are *not* full-fledged members of the EquivalenceClass and do not
affect the class's overall properties at all. They are kept only to
simplify matching of child-relation expressions to EquivalenceClasses.
-Most operations on EquivalenceClasses should ignore child members.
+Most operations on EquivalenceClasses needn't look at child members.
Would that be ok?
David
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