Oracle： EXP－00091 的解决方法
在我们对Oracle做EXP的过程中，可能会经常遇到EXP－00091 Exporting questionable statistics.的信息，其实它就是exp的error message，它产生的原因是因为我们exp工具所在的环境变量是的NLS LANG中的NLS_CHARCATERSET不一致引起的。但需要说明的是，exp-00091这个error对所生成的dump文件没有影响，生成的dump文件还可以正常imp。
下面我们来解决这个问题，让其不在出现：
第一步： 查看DB中的NLS_CHARACTERSET的值（提供两种方法）：查询NLS_CHARACTERSET的值：select * from nls_database_parameters t where t.parameter='NLS_CHARACTERSET'orselect * from v$nls_parameters where parameter='NLS_CHARACTERSET';SQL> select * from v$nls_parameters where parameter='NLS_CHARACTERSET';PARAMETER VALUE----------------------- ----------------------------------------------NLS_CHARACTERSET ZHT16BIG5第二步： 根据第一步查出的NLS_CHARACTERSET（ZHT16BIG5）來設定exp的環境變量：WINNT> set NLS_LANG=AMERICAN_AMERICA.ZHT16BIG5进行设定后，在环境变量中查看NLS_LANG的值是否一致，如果不一致可在环境变量中手中修改。LINUX> export NLS_LANG=AMERICAN_AMERICA.ZHT16BIG5?附上exp-91的oracle error message 解決方案說明：
oerr exp 9100091, 00000, "Exporting questionable statistics."// *Cause: Export was able export statistics, but the statistics may not be// usuable. The statistics are questionable because one or more of// the following happened during export: a row error occurred, client// character set or NCHARSET does not match with the server, a query// clause was specified on export, only certain partitions or// subpartitions were exported, or a fatal error occurred while// processing a table.// *Action: To export non-questionable statistics, change the client character// set or NCHARSET to match the server, export with no query clause,// export complete tables. If desired, import parameters can be// supplied so that only non-questionable statistics will be imported,// and all questionable statistics will be recalculated.?
