COPY allows DELIMITER and NULL to be specified which don't allow the data
to be copied back in properly. Using any delimiter that could be part of
a backslash escape sequence (\n \0 \t) will break if any of the data has a
character matching the delimiter because it will be escaped and then be
read as a special character.
It also allows DELIMITER and NULL to overlap. No character in the NULL
specification should be the DELIMITER.
Kris Jurka
