From: Tom Lane <tgl@sss.pgh.pa.us>
To: Chao Li <li.evan.chao@gmail.com>
cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Fixing some ancient errors in hash join costing
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Comments: In-reply-to Chao Li <li.evan.chao@gmail.com>
	message dated "Mon, 29 Dec 2025 08:39:38 +0800"
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Date: Sun, 28 Dec 2025 22:29:16 -0500
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Chao Li <li.evan.chao@gmail.com> writes:
> Just a few small comments on v2:

> This is not a concern, just curious why switch the setting order of enab=
le_hashjoin and enable_sort?

The need to disable hashjoin only applies to one of the two tests, so
it seemed to me that this way is more nicely nested.  Judgment call
of course.

> As flag 0 is passed to get_attstatsslot(), free_attstatsslot() is not ne=
eded.

True.  I wrote it like that so people wouldn't wonder if I'd forgotten
free_attstatsslot(), but if other call sites passing flags =3D=3D 0 don't
use it then it'd be better to be consistent.  (I didn't check that.)

> Maybe worth adding a short comment like =E2=80=9C0.0 doesn=E2=80=99t mea=
n zero frequency, instead 0.0 means no data or unknown frequency=E2=80=9D,=
 which might help code readers to quickly understand the logic.

Doesn't the function's header comment cover that adequately?

			regards, tom lane