It is that MySQL 5 cannot support characters outside the BMP at all, or
just that it can't collate them properly? If it just handles > BMP UTF-8
sequences as binary data, might it simply sort them in Unicode code
point order?
Or does it do something worse, and actively convert the Unicode
characters into a 16-bit range, thus nuking characters outside the BMP.
rather than storing, and largely processing, them as binary-encoded data
for purposes other than collating?
-- Neil