Re: [PATCH] Extend ALTER OPERATOR to support adding commutator, negator, hashes, and merges

Christoph Berg <myon@debian.org> writes:
> This change is breaking pgsphere which has <@ @> operator pairs, but
> for historical reasons also includes alternative spellings of these
> operators (both called @ with swapped operand types) which now
> explodes because we can't add them with the "proper" commutator and
> negators declared (which point to the canonical <@ @> !<@ !@>
> operators).

Should have guessed that somebody might be depending on the previous
squishy behavior.  Still, I can't see how the above situation is a
good idea.  Commutators/negators should come in pairs, not have
completely random links.  I think it's only accidental that this
setup isn't triggering other strange behavior.

> We might be able to simply delete the @ operators, but doesn't this
> new check break the general possibility to have more than one spelling
> for the same operator?

You can have more than one operator atop the same function.
But why didn't you make the @ operators commutators of each other,
rather than this mess?

            regards, tom lane