Re: bytea_ops

> which categories are present in a column.  For bytea data, there are
> no natural categories and thus no justification for extrapolating
> byte-value distribution from the info available to scalarltsel.  So
> I think there's no defensible argument for using anything but 0..255.
> (I suppose we could consider adding more info to pg_statistic for these
> types of columns, but I'm not eager to do that right at the moment.)

Changes in this rev:

- convert_byte_to_scalar uses 0..255 range always
- eliminated convert_bytea_datum, just pass and use the Datums directly

Results still look good on my random data and passes all regression tests.

-- Joe