will attempt to retrieve the name of the sequence from the database
automatically.
+=item auto_nextval
+
+Set this to a true value for a column whose value is retrieved
+automatically from an oracle sequence. If you do not use an oracle
+trigger to get the nextval, you have to set sequence as well.
+
=item extra
This is used by L<DBIx::Class::Schema/deploy> and L<SQL::Translator>