From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <dgrowleyml@gmail.com>
cc: Richard Guo <guofenglinux@gmail.com>,
        PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: A performance issue with Memoize
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Comments: In-reply-to David Rowley <dgrowleyml@gmail.com>
	message dated "Sat, 27 Jan 2024 10:02:51 +1300"
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Date: Fri, 26 Jan 2024 16:09:00 -0500
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David Rowley <dgrowleyml@gmail.com> writes:
> On Sat, 27 Jan 2024 at 09:41, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> drongo and fairywren are consistently failing the test case added
>> by this commit.  I'm not quite sure why the behavior of Memoize
>> would be platform-specific when we're dealing with integers,
>> but ...

> Maybe snprintf(buf, "%.*f", 0, 5.0 / 2.0); results in "3" on those
> rather than "2"?
> Looking at the code in fmtfloat(), we fallback on the built-in snprintf.

Maybe ... I don't have a better theory.

> I can try changing the unique1 < 5 to unique1 < 4 to see that's more stable.

Worth a try.

			regards, tom lane