You may encounter the following situations when you use external tables to move data between databases:
The database character set and the database national character set may be different between the two platforms.
The endianness of the platforms for the two databases may be different.
ORACLE_DATAPUMP access driver automatically resolves some of these situations.
The following data types are automatically converted during loads and unloads:
If you attempt to use a data type that is not supported for external tables, then you receive an error. This is demonstrated in the following example, in which the unsupported data type,
LONG, is used:
SQL> CREATE TABLE bad_datatype_xt 2 ( 3 product_id NUMBER(6), 4 language_id VARCHAR2(3), 5 translated_name NVARCHAR2(50), 6 translated_description LONG 7 ) 8 ORGANIZATION EXTERNAL 9 ( 10 TYPE ORACLE_DATAPUMP 11 DEFAULT DIRECTORY def_dir1 12 LOCATION ('proddesc.dmp') 13 ); translated_description LONG * ERROR at line 6: ORA-30656: column type not supported on external organized table