Re: A performance issue with Memoize

Hello,

27.01.2024 00:09, Tom Lane wrote:
> 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.

FWIW, I've found where this behaviour is documented:

https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/sprintf-sprintf-l-swprintf-swprintf-l-swprintf-l?view=msvc-170

(I've remembered a case with test/sql/partition_prune from 2020, where
sprintf on Windows worked the other way.)


Best regards,
Alexander