The options UNRECOVERABLE in Oracle7 and NOLOGGING in Oracle8 can be used when creating a table as select. They will send the actual create statement
to the redo logs (this information is needed in the data dictionary). All rows loaded into the table during the create are not sent to the redo logs.

With UNRECOVERABLE in Oracle7 any subsequent Data Manipulation Language (DML) command on the table WILL be sent to the redo logs.

Other SQL statements (such as UPDATE, DELETE, conventional path INSERT, and
various DDL statements not listed above) are unaffected by the NOLOGGING attribute of the schema object.

Thanks for the inputs .