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Overview of High Availability Features
Computing environments configured to provide nearly full-time availability are know as high availability systems. Such systems typically have redundant hardware and software that makes the system available despite failures. Well-designed high availability systems avoid having single points-of-failure.
When failures occur, the fail over process moves processing performed by the failed component to the backup component. This process remasters systemwide 阅读全文
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Overview of Scalability and Performance Features
Oracle includes serveral software mechanisms to fulfill the following important requirements of an information management system:
- Data concurrency of a multiuser system must be maximized.
- Data must be read and modified in a consistent fashion. The data a user is viewing or changing is not changed(by other users) until the user is finished with the data.
- High performance is required for maximum productivity from the many users of 阅读全文
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A schema is a collection of database objects. A schema is owned by a database user and has the same name as that user. Schema objects are the logical structures that directly refer to the database's data. Schema objects include structures like tables, views, and indexes. (There is no relationship between a tablespace and a schema. Objects in the same schema can be in different tablespaces, and a tablespace can hold objects from different schemas.) 阅读全文
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There are 2 common ways to architect a database: client/server or multitier. As internet computing becomes more prevalent in computing environments, many database management systems are moving to a multitier environment. 阅读全文
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An Oracle database is a collection of data treated as unit. The purpose of a database is to store and retrieve related information. A database server is the key to solving the problems of information management. In general, a server reliably manages a large amount of data in a multiuser environment so that many users can concurrently access the same data. All this is accomplished while delivering high performance. A database server also prevents unauthorized access and provides efficient solutio 阅读全文
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Hi，推荐文件给你 "2012OOW-TomOracle12cTop12NewFeature.pdf" http://vdisk.weibo.com/s/fkMj9 阅读全文
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三个配置文件 listener.ora、sqlnet.ora、tnsnames.ora ，都是放在$ORACLE_HOME\network\admin目录下。 阅读全文
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logmnr是用于分析日志的工具，主要有以下几个用途：
1. 查明数据库的改变登记：能够用Logmnr来分析这些事务,看看究竟发生了些什么事情
2. 找回丢失的数据,当不能利用flashback时候,能够利用Logmnr工具来找回数据,这个时候,只必需有归档日志即可. 阅读全文
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Flashback支行的恢复级别包括下列几种：
事务闪回:对表进行了insert,update,delete操作，已经commit了，发现弄错了，需要恢复到某个commit操作之前的数据，则需要撤销刚才的某个操作。
行级闪回:对表进行insert,update,delete操作，需要恢复到时某个时间点。
表级闪回:错误的drop table操作，需要表和表中的数据。
数据库级闪回:错误地对整个数据库导入很多表数据，需要将整个数据库恢复到过去的时间点。 阅读全文
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源库执行初始化过程:dbms_streams_adm.pre_instantiation_setup;dbms_streams_adm.post_instantiation_setup 阅读全文