SQL> CREATE MATERIALIZED VIEW x
  2          REFRESH COMPLETE WITH ROWID
  3          AS SELECT * FROM dual;
Materialized view created.

SQL> set long 32000 pages 50000
SQL> SELECT dbms_metadata.get_ddl('MATERIALIZED_VIEW', 'X')
  2  FROM   dual;
DBMS_METADATA.GET_DDL('MATERIALIZED_VIEW','X')
--------------------------------------------------------------------------------

  CREATE MATERIALIZED VIEW "SYS"."X"
  ORGANIZATION HEAP PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS LOG
GING
  STORAGE(INITIAL 16384 NEXT 16384 MINEXTENTS 1 MAXEXTENTS 505
  PCTINCREASE 50 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)
  TABLESPACE "SYSTEM"
  BUILD IMMEDIATE
  USING INDEX PCTFREE 10 INITRANS 2 MAXTRANS 255
  STORAGE(INITIAL 16384 NEXT 16384 MINEXTENTS 1 MAXEXTENTS 505
  PCTINCREASE 50 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)
  TABLESPACE "SYSTEM"
  REFRESH COMPLETE ON DEMAND
  WITH ROWID USING DEFAULT LOCAL ROLLBACK SEGMENT
  DISABLE QUERY REWRITE
  AS SELECT "DUAL"."DUMMY" "DUMMY" FROM "DUAL" "DUAL"