Oracle EXP/IMP是早期推出数据备份还原工具。因其简单易用、功能强大的特性,广泛的被行业接受。一些开发工具(如PL/SQL Develop
Oracle EXP/IMP是早期推出数据备份还原工具。因其简单易用、功能强大的特性,广泛的被行业接受。一些开发工具(如PL/SQL Developer)中甚至集成嵌入了EXP/IMP工具。一些国内开发团队默认数据部署策略中,EXP/IMP也占到了相当比例。
随着Oracle版本的推进,新特性的推出,特别是海量数据库不断出现在企业应用环境下,传统的EXP/IMP工具架构已经不能承担发展的需要。于是在10g版本中,Oracle推出了服务端运行的数据泵Data Pump工具。到11g版本中,Data Pump已经成为成熟的数据导入导出、备份解决方案。
但是在实际开发领域,Exp/Imp还是有很大的市场。虽然11g中已经不推荐使用Exp/Imp,但是很多厂商部署小数据应用还是采用Exp/Imp方法。
本次记录的是一次部署导出Exp中出现的问题,记录下来,留待需要的朋友需要。
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Oracle 11g 在RedHat Linux 5.8_x64平台的安装手册
Linux-6-64下安装Oracle 12C笔记
在CentOS 6.4下安装Oracle 11gR2(x64)
Oracle 11gR2 在VMWare虚拟机中安装步骤
Debian 下 安装 Oracle 11g XE R2
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1、问题综述
厂商上线部署系统,进行最后的数据导出导入测试。由于不是最终的环境,而且上线系统数据量初始比较少,所以推荐使用Exp/Imp或者Data Pump工具。在导出过程中,系统数据虽然成功导出,但是出现报错EXP-00091。对应截屏照片如下(安全原因,屏蔽部分信息):
导出语法也没有什么额外的信息过程。一时间笔者也没有处理的思路。
2、问题分析和检索
留下错误信息提示和语句信息之后,笔者查询了Oracle MOS官方网站,希望找到对应的资料。在文档EXP Utility Reports EXP-91 During Export (文档 ID 730106.1)中,笔者找到了这个问题的解释。
Oracle统计量是CBO的工作基础。Oracle优化器在发展历程中,经历了从RBO到CBO的演变过程。RBO时代,优化器生成规则是以代码的方式固化在Oracle代码中的。而CBO的工作是基于数据对象统计量。统计量反映在实体上,就是一系列的元数据信息。在9i时代,CBO与RBO共同作用,而且统计量是需要人工进行收集维护的。而且,由于数据变化的原因,在一些早期CBO版本中,“实时”统计量往往还不能获得最好的执行计划。
所以,在9i的Exp/Imp工具开始,统计量导出就成为Exp工具默认行为。Exp/Imp工具是一个客户端工具,客户端的字符集设置nls_lang和数据库服务器端是存在不同的。如果nls_lang环境变量设置与数据库服务器设置不同,就会导致这个问题出现。
下面我们通过实验来试图重现错误,来证实我们的推论。
3、错误模拟
我们使用oracle 11gR2来进行测试模拟,具体版本号为11.2.0.4。客户端操作系统为Windows。
SQL> select * from v$version;
BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
PL/SQL Release 11.2.0.4.0 - Production
CORE 11.2.0.4.0 Production
TNS for 64-bit Windows: Version 11.2.0.4.0 - Production
NLSRTL Version 11.2.0.4.0 – Production
当前,服务器NLS关键参数如下。注意,查看nls信息一定是数据库层面的。
SQL> select * from nls_database_parameters;
PARAMETER VALUE
------------------------------ --------------------------------------------------------------------------------
NLS_LANGUAGE AMERICAN
NLS_TERRITORY AMERICA
NLS_CURRENCY $
NLS_ISO_CURRENCY AMERICA
NLS_NUMERIC_CHARACTERS .,
NLS_CHARACTERSET AL32UTF8
(篇幅原因,有省略……)
Nls_lang环境变量的参数格式包括nls_language、nls_territory和nls_characterset。具体格式如下:
NLS_LANG=_.
更多详情见请继续阅读下一页的精彩内容:

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