使用dbms_metadata.get_ddl出现ORA-31605错误

SQL> select * from v$version;
BANNER
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Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
PL/SQL Release 9.2.0.4.0 - Production
CORE    9.2.0.3.0       Production
TNS for Linux: Version 9.2.0.4.0 - Production
NLSRTL Version 9.2.0.4.0 - Production
SQL> select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') "www.xifenfei.com" from dual;
www.xifenfei.com
-------------------
2012-05-26 23:10:22
SQL> select dbms_metadata.get_ddl('TABLE','XFF_IOT','CHF1') from dual;
ERROR:
ORA-06502: PL/SQL: numeric or value error
ORA-31605: the following was returned from LpxXSLResetAllVars in routine kuxslResetParams:
LPX-1: NULL pointer
ORA-06512: at "SYS.UTL_XML", line 0
ORA-06512: at "SYS.DBMS_METADATA_INT", line 3320
ORA-06512: at "SYS.DBMS_METADATA_INT", line 4148
ORA-06512: at "SYS.DBMS_METADATA", line 458
ORA-06512: at "SYS.DBMS_METADATA", line 615
ORA-06512: at "SYS.DBMS_METADATA", line 1221
ORA-06512: at line 1
no rows selected

错误原因
dbms_metadata.get_ddl需要调用Oracle dictionary table “sys.metastylesheet.”中的XSL stylesheets,但是由于某种原因,使得调用失败,出现上述错误.因为该错误可能有:
1.XSL stylesheets没有安装
2.使用alter database 修改数据库字符集(本库是因为昨天修改字符集导致)

解决办法(sys用户执行)
1.在10g及其以上版本中(不带参数)

SQL> exec dbms_metadata_util.load_stylesheets;
PL/SQL procedure successfully completed.

2.在9i版本中(带dir参数)

SQL> exec dbms_metadata_util.load_stylesheets('/u01/oracle/9.2.0/db_1/rdbms/xml/xsl');
PL/SQL procedure successfully completed.
SQL> select dbms_metadata.get_ddl('TABLE','XFF_IOT','CHF1') from dual;
DBMS_METADATA.GET_DDL('TABLE','XFF_IOT','CHF1')
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  CREATE TABLE "CHF1"."XFF_IOT"
   (    "ID" NUMBER,
        "NAME" VARCHAR2(30),
         CONSTRAINT "CHF_IOT_ID#_PK" PRIMARY KEY ("ID") ENABLE
   ) ORGANIZATION INDEX NOCOMPRESS PCTFREE 10 INITRANS 2 MAXTRANS 255 LOGGING
  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)
  TABLESPACE "SYSTEM"
 PCTTHRESHOLD 50
DBMS_METADATA.GET_DDL('TABLE','XFF_IOT','CHF1')
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