Victor Snezhko <snezhko@indorsoft.ru> writes:
> But... maybe I misunderstand something fundamental, but should isspace
> work when we pass one byte of multibyte character?
Yes, it should, because we only allow ASCII-superset encodings inside
the backend. That is, characters that actually occupy multiple bytes
must have the high bit set in each such byte, and we expect that
isspace, isdigit, etc will not return true for any such byte.
regards, tom lane
