Horton

Re: Sort functions with specialized comparators

John Naylor <johncnaylorls@gmail.com>

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From: John Naylor <johncnaylorls@gmail.com>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: "Andrey M. Borodin" <x4mmm@yandex-team.ru>, David Rowley <dgrowleyml@gmail.com>, Антуан Виолин <violin.antuan@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2025-01-07T04:57:45Z
Lists: pgsql-hackers 
On Tue, Jan 7, 2025 at 12:47 AM Nathan Bossart <nathandbossart@gmail.com> wrote:
>
> On Mon, Jan 06, 2025 at 05:54:29PM +0700, John Naylor wrote:
> > Those functions from common/int.h are probably not good when inlined
> > (see comment there).
>
> +1.  In fact, I think this comment was added because of the ST_MED3()
> function in sort_template.h [0].  IIRC clang handles this just fine, but
> gcc does not.
>
> [0] https://postgr.es/m/20240212230423.GA3519%40nathanxps13

Yeah. If it were just med3, it would probably be okay, but I remember
earlier experiments (also gcc) where branch-free comparators seemed to
not work well with our partitioning scheme.

-- 
John Naylor
Amazon Web Services

Commits

  1. Specialize intarray sorting

  2. Replace insertion sort in contrib/intarray with qsort().