On 2/28/25 17:49, Thomas Munro wrote:
On Sat, Mar 1, 2025 at 9:03 AM Joe Conway <mail@xxxxxxxxxxxxx> wrote:
On 2/28/25 09:16, Laurenz Albe wrote:
> On Thu, 2025-02-27 at 16:54 +0300, Alexey Borschev wrote:
>> I see poor performance of text sorting of collate "en_US.utf8" in PG 17.4.
>
> I'd say that you would have to complain to the authors of the
> GNU C library, which provides this collation.
Yep -- glibc starting with version 2.21 has a massive performance
regression for certain cases and the glibc folks have basically said
they will not fix it. If you try the same thing on RHEL 7.x with glibc
2.17 it will perform about the same as ICU.
I've idly wondered if this is the culprit, do you know?
https://github.com/bminor/glibc/commit/0742aef6e52a935f9ccd69594831b56d807feef3
Yes, that was definitely the one that caused the regression. Note that
if you look closely you will find there is a revert of that patch on
glibc on certain distros. But not on RHEL and RHEL-alike.
Someone else pointed out this thread to me:
https://sourceware.org/bugzilla/show_bug.cgi?id=18441
Note the last message on that thread:
8<--------------
Carlos O'Donell 2019-05-09 20:44:56 UTC
(In reply to vectoroc from comment #13)
> Hello. Is there any chance that the issues will be fixed? Unfortunately
> PostgreSQL Is unable to use ICU some base features (e.g in analyze
> operation).
We haven't had anyone working on strcoll_l performance improvements. So
it's unlikely that this will get merged or reviewed any time soon.
8<--------------
--
Joe Conway
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
