Re: Collation-aware comparisons in GIN opclasses

Peter Geoghegan <pg@heroku.com> writes:
> On Mon, Sep 15, 2014 at 8:28 AM, Alexander Korotkov
> <aekorotkov@gmail.com> wrote:
>> Rename such opclasses and make them not default.
>> Create new default opclasses with bitwise comparison functions.
>> Write recommendation to re-create indexes with default opclasses into
>> documentation.

> I certainly think this should be fixed if at all possible, but I'm not
> sure about this plan. Can we really rename an opclass without
> consequence, including having that respected across pg_upgrade?

No.  And we don't know how to change the default opclass without
breaking things, either.  See previous discussions about how we
might fix the totally-broken default gist opclass that btree_gist
creates for the inet type [1].  The motivation for getting rid of that
is *way* stronger than "it might be slow", but there's no apparent
way to make something else be the default without creating havoc.
        regards, tom lane

[1] http://www.postgresql.org/message-id/flat/CAE2gYzyUESd188j0b290Gf16502H9B-LwNRS3rFi1SwDb9Qcgw@mail.gmail.com