在进行EXP的时候出现EXP-00091

oracle@wxsz001:~> exp scott/tiger tables=emp file=/opt/oracle/back/emp.dmp

Export: Release 10.2.0.1.0 - Production on Mon May 10 15:48:15 2010

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
Export done in US7ASCII character set and AL16UTF16 NCHAR character set
server uses ZHS16GBK character set (possible charset conversion)

About to export specified tables via Conventional Path ...
. . exporting table                            EMP         14 rows exported
EXP-00091: Exporting questionable statistics.
EXP-00091: Exporting questionable statistics.
Export terminated successfully with warnings.

看帮助提示：

oracle@wxsz001:~> oerr exp 91
00091, 00000, "Exporting questionable statistics."00091, 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.

可能是字符集问题：

oracle@wxsz001:~> export NLS_LANG=american_america.ZHS16GBK
oracle@wxsz001:~> exp scott/tiger tables=emp file=/opt/oracle/back/emp1.dmp

Export: Release 10.2.0.1.0 - Production on Mon May 10 15:54:08 2010

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
Export done in ZHS16GBK character set and AL16UTF16 NCHAR character set

About to export specified tables via Conventional Path ...
. . exporting table                            EMP         14 rows exported
Export terminated successfully without warnings.

问题解决。。字符集问题。。。。