Re: Move defaults toward ICU in 16?
| От | Pavel Stehule |
|---|---|
| Тема | Re: Move defaults toward ICU in 16? |
| Дата | |
| Msg-id | CAFj8pRAGgzyyEOBjkuNCo2tXnyzmENPF0YjtpK5vtqQ2efsviw@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Move defaults toward ICU in 16? (Jeff Davis <pgsql@j-davis.com>) |
| Список | pgsql-hackers |
pá 17. 2. 2023 v 21:43 odesílatel Jeff Davis <pgsql@j-davis.com> napsal:
On Fri, 2023-02-17 at 18:27 +0100, Pavel Stehule wrote:
> Today I tested icu for Czech sorting. It is a little bit slower, but
> not too much, but it produces partially different results.
Thank you for trying it.
If it's a significant slowdown, can you please send more information?
ICU version, libc version, and testcase?
no - this slowdown is not significant - although 1% can looks too much - but it is just two ms
It looks so libicu has little bit more expensive initialization, but the execution is little bit faster
But when I try to repeat the measurements, the results are very unstable on my desktop :-/
SELECT * FROM obce ORDER BY nazev LIMIT 10 // is faster with glibc little bit
SELECT * FROM obce ORDER BY nazev // is faster with libicu
You can download dataset https://pgsql.cz/files/obce.sql
It is table of municipalities in czech republic (real names) - about 6000 rows
I use fedora 37 - so libicu 71.1, glibc 2.36
Regards
Pavel
> select row_number() over (order by nazev collate "cs-x-icu"), nazev
> from obce
> except select row_number() over (order by nazev collate "cs_CZ"),
> nazev from obce;
>
> returns a not empty set. So minimally for Czech collate, an index
> rebuild is necessary
Yes, that's true of any locale change, provider change, or even
provider version change.
--
Jeff Davis
PostgreSQL Contributor Team - AWS
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