Strings and ustrings

If you have NLS enabled, parallel jobs support two types of underlying character data types: strings and ustrings.

String data represents unmapped bytes, and ustring data represents full Unicode (UTF-16) data.

The Char, VarChar, and LongVarChar SQL types relate to underlying string types where each character is 8-bits and does not require mapping because it represents an ASCII character. You can, however, specify that these data types are extended, in which case they are taken as ustrings and do require mapping. (They are specified as such by selecting the Extended check box for the column in the Edit Meta Data dialog box.) An Extended field appears in the columns grid, and extended Char, VarChar, or LongVarChar columns have `Unicode' in this field. The NChar, NVarChar, and LongNVarChar types relate to underlying ustring types so do not need to be explicitly extended.