Re: pg_collation.collversion for C.UTF-8

On 6/6/23 15:23, Jeff Davis wrote:
> On Mon, 2023-06-05 at 19:43 +0200, Daniel Verite wrote:
>> But in the meantime, personally I don't quite see why Postgres should
>> start forcing C.UTF-8 to sort differently in the database than in the
>> OS.
>
> I can see both points of view. It could be surprising to users if
> C.UTF-8 does not sort like C/memcmp, or surprising if it changes out
> from under them. It could also be surprising that it wouldn't sort like
> the current OS's libc interpretation of C.UTF-8.
>
> What about ICU? How should provider=icu locale=C.UTF-8 behave? We
> could:
>
> a. Just pass it to the provider and see what happens (older versions of
> ICU would interpret it as en-US-u-va-posix; newer versions would give
> the root locale).
>
> b. Consistently interpret it as en-US-u-va-posix.
>
> c. Don't pass it to the provider at all and treat it with memcmp
> semantics.

Personally I think this should be (a). However we should also clearly
document that the semantics of such is provider/OS dependent and
therefore may not be what is expected/desired.

--
Joe Conway
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com