Merlin Moncure <mmoncure@gmail.com> writes:
> right, json could be made work, but any other format change introduced
> to any other already existing type will break. That's not a real
> solution unless we decree henceforth that no formats will change from
> here on in, in which case I withdraw my objection.
Well, I don't recall that we've made a practice of changing binary formats
a lot. Doing so would break existing dumps, which is something we
strenuously avoid.
Even granting that sometime in the future we invent infrastructure to do
the kind of protocol negotiation you're talking about, one byte per JSON
value seems like a cheap and worthwhile cross-check that both ends came
to the same conclusion about what to send.
regards, tom lane