Oracle 11g 導出報錯exp-00091，解決辦法。

今天做數據庫導出報錯：EXP-00091: Exporting questionable statistics.
在對ORACLE數據庫做exp備份導出時報EXP-00091: Exporting questionable statistics”錯誤：詳情如下：
EXP-00091: Exporting questionable statistics.
EXP-00091: Exporting questionable statistics.
EXP-00091: Exporting questionable statistics.
. . exporting table test 12 rows exported
EXP-00091: Exporting questionable statistics.
. . exporting table users 129 rows exported
EXP-00091: Exporting questionable statistics.
EXP-00091: Exporting questionable statistics.
EXP-00091: Exporting questionable statistics.
EXP-00091: Exporting questionable statistics.
問題原因：
引起此問題的原因是數據庫字符集和操作系統的NLS_LANG不一致導致
處理方法：
查詢數據庫的字符集信息
SQL> select userenv('language') from dual;

USERENV('LANGUAGE')

AMERICAN_AMERICA.WE8ISO8859P1
設置操作系統的NLS_LANG值
export NLS_LANG=AMERICAN_AMERICA.WE8ISO8859P1
重新運行數據庫導出命令
exp system/oracle file='/tmp/full.dmp' full=y;