Sun Jul 23 22:09:07 2017
DBMS_STATS: GATHER_STATS_JOB encountered errors. Check the trace file.
Errors in file /u01/app/oracle/diag/rdbms/orcl/orcl2/trace/orcl2_j001_3605192.trc:
ORA-20011: Approximate NDV failed: ORA-29913: error in executing ODCIEXTTABLEOPEN callout
KUP-11024: This external table can only be accessed from within a Data Pump job.

问题处理：参考https://community.oracle.com/thread/2477501

select OWNER,OBJECT_NAME,OBJECT_TYPE, status,
to_char(CREATED,'dd-mon-yyyy hh24:mi:ss') created
,to_char(LAST_DDL_TIME , 'dd-mon-yyyy hh24:mi:ss') last_ddl_time
from dba_objects
where object_name like 'ET$%'

OWNER　　　　OBJECT_NAME　　　　OBJECT_TYPE　　status

dbmonitor　　　　ET$047D99EB0001　　table　　　　　　　active

SQL> drop table dbmonitor.ET$047D99EB0001;