Re: pgsql: Allow tailoring of ICU locales with custom rules - Mailing list pgsql-hackers

From Peter Eisentraut
Subject Re: pgsql: Allow tailoring of ICU locales with custom rules
Date
Msg-id ad36444d-a2ea-7874-68df-34bd22391c3f@enterprisedb.com
Whole thread Raw
Responses Re: pgsql: Allow tailoring of ICU locales with custom rules
List pgsql-hackers
On 08.03.23 21:57, Jeff Davis wrote:
> On Wed, 2023-03-08 at 16:03 +0000, Peter Eisentraut wrote:
>> Allow tailoring of ICU locales with custom rules
> 
> Late review:
> 
> * Should throw error when provider != icu and rules != NULL

I have fixed that.

> * Explain what the example means. By itself, users might get confused
> wondering why someone would want to do that.
> 
> * Also consider a more practical example?

I have added a more practical example with explanation.

> * It appears rules IS NULL behaves differently from rules=''. Is that
> desired? For instance:
>    create collation c1(provider=icu,
>      locale='und-u-ka-shifted-ks-level1',
>      deterministic=false);
>    create collation c2(provider=icu,
>      locale='und-u-ka-shifted-ks-level1',
>      rules='',
>      deterministic=false);
>    select 'a b' collate c1 = 'ab' collate c1; -- true
>    select 'a b' collate c2 = 'ab' collate c2; -- false

I'm puzzled by this.  The general behavior is, extract the rules of the 
original locale, append the custom rules, use that.  If the custom rules 
are the empty string, that should match using the original rules 
untouched.  Needs further investigation.

> * Can you document the interaction between locale keywords
> ("@colStrength=primary") and a rule like '[strength 2]'?

I'll look into that.




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