Re: pgsql: Allow tailoring of ICU locales with custom rules

On Fri, Mar 10, 2023 at 3:24 PM Peter Eisentraut
<peter.eisentraut@enterprisedb.com> wrote:
>
> On 08.03.23 21:57, Jeff Davis wrote:
>
> > * 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.
>

This thread is listed on PostgreSQL 16 Open Items list. This is a
gentle reminder to see if there is a plan to move forward with respect
to open points.

--
With Regards,
Amit Kapila.