Re: Re: CREATE COLLATION does not sanitize ICU's BCP 47 language tags. Should it?

On Sat, Sep 30, 2017 at 11:25:43AM -0400, Tom Lane wrote:
> Noah Misch <noah(at)leadboat(dot)com> writes:
> > On Mon, Sep 25, 2017 at 09:36:44AM -0700, Peter Geoghegan wrote:
> >>> I think it's inevitable that a certain number of users are going to
> >>> have to cope with ICU version changes breaking stuff.
>
> >> Wasn't the main point of adopting ICU that that doesn't happen when it
> >> isn't essential?
>
> > I wouldn't describe it that way. I agree that few, if any, ICU upgrades will
> > remove country or language codes. Overall, though, almost every ICU upgrade
> > will be difficult. Each ICU release, even a minor release like 58.2, changes
> > the sorting rules in some tiny way. You then see "Rebuild all objects
> > affected by this collation" messages.
>
> Sure, but dealing with that is mechanical: reindex the necessary indexes
> and you're done.

In the general case, one must revalidate CHECK constraints, re-partition
tables, revalidate range values, and reindex.

> In the libc world,
> when you upgrade libc's locale definitions, you have no idea what the
> consequences are.

Yep. It's strictly better than the libc case.