Re: ICU_LOCALE set database default icu collation but not working as intended.

Hi, here are some other trigger cases.

CREATE DATABASE dbicu3 LOCALE_PROVIDER icu LOCALE 'en_US.UTF-8'
ICU_LOCALE 'en-u-kr-latn-digit-kf-upper-kn-true' TEMPLATE 'template0';
CREATE DATABASE dbicu4 LOCALE_PROVIDER icu LOCALE 'en_US.UTF-8'
ICU_LOCALE 'en-u-kr-latn-digit-kn-true' TEMPLATE 'template0';
--mistake
CREATE DATABASE dbicu5 LOCALE_PROVIDER icu LOCALE 'en_US.UTF-8'
ICU_LOCALE 'en-u-kr-latn-digit-kr-upper' TEMPLATE 'template0';
CREATE DATABASE dbicu6 LOCALE_PROVIDER icu LOCALE 'en_US.UTF-8'
ICU_LOCALE 'en-u-kr-latn-digit-kf-upper' TEMPLATE 'template0';

--same script applies to dbicu3, dbicu4, dbicu5, dbicu6.
begin;
CREATE COLLATION upperfirst (provider = icu, locale = 'en-u-kf-upper');
CREATE TABLE icu(def text, en text COLLATE "en_US", upfirst text COLLATE
upperfirst, test_kr text);
INSERT INTO icu VALUES ('a', 'a', 'a', '1 a'), ('b','b','b', 'A 11'),
('A','A','A','A 19'), ('B','B','B', '8 p');
INSERT INTO icu VALUES ('a', 'a', 'a', 'a 7'),('a', 'a', 'a', 'a 117');
INSERT INTO icu VALUES ('a', 'a', 'a', 'a 70'), ('a', 'a', 'a', 'A 70');
INSERT INTO icu VALUES ('a', 'a', 'a', 'Π1');
commit ;
-----------------------
localhost:5433 admin(at)dbicu3=# SELECT test_kr FROM icu ORDER BY test_kr ;

test_kr
---------
a 7
A 11
A 19
A 70
a 70
a 117
Π1
1 a
8 p
(9 rows)
--------------------------------------
localhost:5433 admin(at)dbicu4=# SELECT test_kr FROM icu ORDER BY test_kr ;
test_kr
---------
a 7
A 11
A 19
a 70
A 70
a 117
Π1
1 a
8 p
(9 rows)
------------------------------------------------------------------------
localhost:5433 admin(at)dbicu6=# SELECT test_kr FROM icu ORDER BY test_kr ;
test_kr
---------
A 11
a 117
A 19
a 7
A 70
a 70
Π1
1 a
8 p
(9 rows)
-----------------------------------------------------------------------------

- dbicu3, ICU_LOCALE 'en-u-kr-latn-digit-kf-upper-kn-true' seems
'kf-upper' not grouped strings beginning with character 'A' together?

- dbicu4, ICU_LOCALE 'en-u-kr-latn-digit-kn-true' since upper/lower not
explicitly mentioned, and since the collation is deterministic, so
character 'A' should be grouped together first then do the numeric value
comparison.

- dbicu6, ICU_LOCALE 'en-u-kr-latn-digit-kf-upper' , from the
result, *kr-latn-digit
*is working as intended. But *kf-upper *seems not working.

maybe this link(
https://www.unicode.org/reports/tr35/tr35-collation.html#314-case-parameters
) can help.

Can I specify as many key-value settings options (
https://www.unicode.org/reports/tr35/tr35-collation.html#table-collation-settings)
as I want in ICU_LOCALE while I create a new database?

On Fri, May 27, 2022 at 1:44 AM Daniel Verite <daniel(at)manitou-mail(dot)org>
wrote:

> jian he wrote:
>
> > CREATE
> > DATABASE dbicu1 LOCALE_PROVIDER icu LOCALE 'en_US.UTF-8' ICU_LOCALE
> > 'en-u-kf-upper' TEMPLATE 'template0';
> > CREATE DATABASE dbicu2 LOCALE_PROVIDER icu LOCALE 'en_US.UTF-8'
> ICU_LOCALE
> > 'en-u-kr-latn-digit' TEMPLATE 'template0';
> > [...]
> > I am not sure this is my personal misunderstanding.
> > In the above examples, the first character of column *test_kr*
> > is so different that the comparison is based on the first letter.
> > If the first letter is the same then compute the second letter..
> > So for whatever collation, I should expect 'A 19' to be adjacent with 'A
> > 11'?
>
> The query "SELECT test_kr FROM icu ORDER BY def;"
> does not order by test_kr, so the contents of test_kr have no bearing
> on the order of the results.
>
> If you order by test_kr, the results look like what you're expecting:
>
> dbicu1=# SELECT test_kr,def FROM icu ORDER BY test_kr;
> test_kr | def
> ---------+-----
> 1 a | a
> 8 p | B
> A 11 | b
> A 19 | A
> a 7 | a
> Π1 | a
>
> dbicu2=# SELECT test_kr,def FROM icu ORDER BY test_kr ;
> test_kr | def
> ---------+-----
> A 11 | b
> A 19 | A
> a 7 | a
> Π1 | a
> 1 a | a
> 8 p | B
>
>
>
> Best regards,
> --
> Daniel Vérité
> https://postgresql.verite.pro/
> Twitter: @DanielVerite
>

--
I recommend David Deutsch's <<The Beginning of Infinity>>

Jian