Re: pg_dump losing index column collations for unique and primary keys

I wrote:
> In short, I'd say the bug here is not pg_dump's fault at all,
> but failure to insist on collation match in ADD PRIMARY KEY
> USING INDEX.

Concretely, I think we should do the attached.

I'm not quite sure whether we should back-patch this, though.
It's been wrong since we added collations, but the main impact
of a back-patch might be to break cases that were working more
or less okay for people.

A compromise idea is to back-patch only into v12, where the issue
became quite a lot more important due to nondeterministic
collations.

Thoughts?

			regards, tom lane