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Export/Import and NLS ConsiderationsBookmarkFixed font Go to EndDoc ID: Note:15095.1Subject: Export/Import and NLS ConsiderationsType: FAQStatus: PUBLISHEDContent Type: TEXT/PLAINCreation Date: 15-JUL-1998Last Revision Date: 21-JUL-2004Introduction ------------ This note provides an in-depth overview of exp/imp and NLS, you may not need to know all this if you just want to take a export and make sure you don't lose any data. Please read this first: [NOTE:227332.1] NLS considerations in Import/E

1.2.2 Understanding the Cost-Based Optimizer  The cost-based optimizer is a more sophisticated facility than the rule-based optimizer. To determine the best execution path for a statement, it uses database information such as table size, number of rows, key spread, and so forth, rather than rigid rules. CBO 是比RBO 更智能的工具.使用最优的执行路径由以下database 信息决定,如 table Size,行数量,键值的分布,因此比严格的RBO 要灵活. The information required by the cost-based optimizer is a

1.2.4 Which Optimizer to Use? If you are currently using the rule-based optimizer, I strongly recommend that you transfer to the cost-based optimizer. Here is a list of the reasons why: • The time spent coding is reduced. • Coders do not need to be aware of the rules. • There are more features, and far more tuning tools, available for the cost-based optimizer. • The chances of third-party packages performing well has been improved considerably. Many third-party packages a

cle 8 数据链路在程式中不能支持：    ODBC        数据不可提交，无错误，偶尔会有错误。    Microsoft OLE DB         数据不可提交，无错误    Oralce OLE DB (在BPCS上可以，但在Cimprod不可以)       错误为:        ORA-02041: client database did not begin a transaction    Oracle的说明：cause: An update occurred a

/*理解Rule-based 优化器       RBO 优先使用预定义方法去计算使用的某条路径访问数据库资料.     RDBMS 使用下列条件则优先选择RBO的优化器.包括:在init.ora 文件中设定OPTIMIZER_MODE = RULE 在init.ora 文件中设定OPTIMIZER_MODE = choose,并且在SQL 中所包含的Table 没有统计资料. 在Session 中使用 alter session set optimizer_mode=rule 在Session 中使用 Alter session set optomizer_mode=Choose 命令,并且SQL 中的任何table 都没有统计资料  Rule hint (例如 select /*+RULE

Oracle8i,9i 中对Long 操作有一个限制.就是:所有的select,Update,lock tables 的所有Long columns 必须在同一个Database中. 而你的SQL,正好选取了两个long columns 分别在两个database 上.所以会出现 ora-00997 的错误. -----原始邮件-----发件人: Harrison Jiang 发送时间: 2005年4月19日 13:11收件人: Lis Li主题: all_tab_columnsselect a.column_name,a.data_type,a.data_length,a.nullable,a.data_default,b.data_type,b.data_length,b.nullable,b.data_defaultfrom all_tab_columns a,all_tab_columns@acmtest bwhere a.o