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.