INSERT INTO physical_table SELECT * FROM external_table

SCOTT@orcl_11g> CREATE OR REPLACE DIRECTORY my_dir as 'C:\oracle11g'
  2  /

Directory created.

SCOTT@orcl_11g> CREATE TABLE external_table
  2    (col1   VARCHAR2(8),
  3  	col2   NUMBER)
  4  ORGANIZATION EXTERNAL
  5    (TYPE ORACLE_LOADER
  6  	DEFAULT DIRECTORY my_dir
  7  	ACCESS PARAMETERS
  8  	  (RECORDS DELIMITED BY NEWLINE
  9  	   LOGFILE 'ext_tab.log'
 10  	   FIELDS TERMINATED BY ','
 11  	   LDRTRIM
 12  	   MISSING FIELD VALUES ARE NULL)
 13  	LOCATION ('old_file.txt'))
 14  REJECT LIMIT UNLIMITED
 15  /

Table created.

SCOTT@orcl_11g> CREATE MATERIALIZED VIEW physical_mview AS
  2  SELECT col1, col2 FROM external_table
  3  /

Materialized view created.

SCOTT@orcl_11g> SELECT * FROM physical_mview
  2  /

COL1           COL2
-------- ----------
old data         10
old data         20
old data         30
old data         40

SCOTT@orcl_11g> ALTER TABLE external_table LOCATION ('new_file.txt')
  2  /

Table altered.

SCOTT@orcl_11g> EXEC DBMS_MVIEW.REFRESH ('physical_mview')

PL/SQL procedure successfully completed.

SCOTT@orcl_11g> SELECT * FROM physical_mview
  2  /

COL1           COL2
-------- ----------
new data         11
new data         21
new data         31
new data         41

SCOTT@orcl_11g>