Re: Allow tailoring of ICU locales with custom rules

On 14.02.23 17:53, Laurenz Albe wrote:
> On Mon, 2023-02-06 at 22:16 +0100, Peter Eisentraut wrote:
>> Right.  Here is a new patch with this fixed.
>
> Thanks. I played some more with it, and still are still some missing
> odds and ends:
>
> - There is a new option ICU_RULES to CREATE DATABASE, but it is not
> reflected in \h CREATE DATABASE. sql_help_CREATE_DATABASE() needs to
> be amended.

Fixed.

> - There is no way to show the rules except by querying "pg_collation" or
> "pg_database". I think it would be good to show the rules with
> \dO+ and \l+.

Fixed. I adjusted the order of the columns a bit, to make the overall
picture more sensible. The locale provider column is now earlier, since
it indicates which of the subsequent columns are applicable.

> - If I create a collation "x" with RULES and then create a database
> with "ICU_LOCALE x", the rules are not copied over.
>
> I don't know if that is intended or not, but it surprises me.
> Should that be a WARNING? Or, since creating a database with a collation
> that does not exist in "template0" doesn't make much sense (or does it?),
> is there a way to forbid that?

This is a misunderstanding of how things work. The value of the
database ICU_LOCALE attribute is passed to the ICU library. It does not
refer to a PostgreSQL collation object.