个人自行阅读时候，翻译的文档。因为比较渣，如果有更合理或者错误的地方烦劳告知，我会做修改。

As explained in Oracle Database Concepts, Oracle Flashback Technology complements your physical backup and recovery strategy. This set of features provides an additional layer of data protection. Specifically, you can use the various features of Oracle Flashback to view past states of data and rewind your database without restoring backups or performing point-in-time recovery. In general, flashback features are more efficient and less disruptive than media recovery in most situations in which they apply.

如Oracle数据库概念中所述，Oracle Flashback技术补充了物理备份和恢复策略。 这组功能提供了一个额外的数据保护层。 具体来说，您可以使用Oracle Flashback的各种功能查看数据的过去状态并回滚数据库，而无需恢复备份或执行时间点恢复。 一般来说，在大多数情况下，闪回功能比介质恢复更高效，更少破坏性。

Oracle Flashback Technology enables you to use the following functionality:
• Logical Flashback Features
• Flashback Database
Oracle闪回技术使您能够使用以下功能：
• 逻辑闪回特性
• 闪回数据库

Logical Flashback Features
Most of the flashback features of Oracle operate at the logical level, enabling you to view and manipulate database objects. The logical-level flashback features of Oracle do not depend on RMAN and are available whether or not RMAN is part of your backup strategy. Except for Oracle Flashback Drop, the logical flashback features rely on undo data, which are records of the effects of each database update and the values overwritten in the update.

Oracle的大多数闪回功能在逻辑级运行，使您能够查看和操作数据库对象。 Oracle的逻辑级闪回功能不依赖于RMAN，并且无论RMAN是否是备份策略的一部分，都是可用的。 除了Oracle Flashback Drop，逻辑闪回功能依赖于撤销数据，记录了每个数据库更新所影响的记录和在更新时重写的数值。

Oracle Database includes the following logical flashback features:

Oracle数据库包括以下逻辑闪回功能：

• Oracle Flashback Query
You can specify a target time and run queries against a database, viewing results as
they would appear at the target time. To recover from an unwanted change like an
update to a table, you could choose a target time before the error and run a query
to retrieve the contents of the lost rows. Oracle Database Development Guide explains how to use this feature.

您可以指定目标时间并对数据库运行查询，查看在目标时间显示的结果。 要从不需要的更改（如更新表）中恢复，可以选择错误之前的目标时间，然后运行查询以检索丢失行的内容。 Oracle数据库开发指南解释了如何使用此功能。

• Oracle Flashback Version Query
You can view all versions of all rows that ever existed in one or more tables in a
specified time interval. You can also retrieve metadata about the differing versions
of the rows, including start and end time, operation, and transaction ID of the
transaction that created the version. You can use this feature to recover lost data
values and to audit changes to the tables queried. Oracle Database Development Guide explains how to use this feature.

您可以在指定的时间间隔中查看一个或多个表中存在的所有行的所有版本。 您还可以检索有关行的不同版本的元数据，包括创建版本的事务的开始和结束时间，操作和事务ID。 您可以使用此功能恢复丢失的数据值，并审计对所查询的表的更改。Oracle数据库开发指南解释了如何使用此功能。

• Oracle Flashback Transaction Query
You can view changes made by a single transaction, or by all the transactions
during a specific time period. Oracle Database Development Guide explains how to
use this feature.

Oracle 闪回事务查询
您可以查看单个事务或在特定时间段内的所有事务所做的更改。 Oracle数据库开发指南解释了如何使用此功能。

• Oracle Flashback Transaction
You can reverse a transaction. Oracle Database determines the dependencies
between transactions and in effect creates a compensating transaction that reverses the unwanted changes. The database rewinds to a state as if the transaction, and any transactions that could be dependent on it, had never happened. Oracle Database Development Guide explains how to use this feature.
您可以回退事务。 Oracle数据库确定事务之间的依赖关系，并且实际上创建了一个补偿事务，以回退不需要的更改。 数据库回退到一个状态，好像事务和可能依赖它的任何事务从未发生过。 Oracle数据库开发指南解释了如何使用此功能。

• Oracle Flashback Table
You can recover a table or set of tables to a specified point in time earlier without
taking any part of the database offline. In many cases, Flashback Table eliminates
the need to perform more complicated point-in-time recovery operations.
Flashback Table restores tables while automatically maintaining associated
attributes such as current indexes, triggers, and constraints, and in this way
enabling you to avoid finding and restoring database-specific properties.“Rewinding a Table with Flashback Table” explains how to use this feature.

您可以将表或表集合恢复到指定的时间点，而不使数据库的任何部分脱机。 在许多情况下，Flashback Table消除了执行更复杂的时间点恢复操作的需要。 闪回表恢复表，同时自动维护相关属性（如当前索引，触发器和约束），从而使您能够避免查找和恢复特定于数据库的属性。 “使用闪回表回滚表”说明如何使用此功能。

• Oracle Flashback Drop
You can reverse the effects of a DROP TABLE statement. “Rewinding a DROP
TABLE Operation with Flashback Drop” explains how to use this feature.
您可以回退DROP TABLE语句的效果。 “使用Flashback Drop重新执行DROP TABLE操作”说明如何使用此功能。

A flashback data archive enables you to use some logical flashback features to access data from far back in the past. A flashback data archive consists of one or more tablespaces or parts of tablespaces. When you create a flashback data archive, you specify the name, retention period, and tablespace. You can also specify a default flashback data archive. The database automatically purges old historical data the day after the retention period expires.

闪回数据存档允许您使用一些逻辑闪回功能来访问过去很久的数据。 闪回数据存档由一个或多个表空间或表空间的一部分组成。 创建闪回数据存档时，可以指定名称，保留期限和表空间。 您还可以指定默认闪回数据归档。 数据库在保留期过期后的第二天自动清除旧的历史数据。

You can turn flashback archiving on and off for individual tables. By default, flashback archiving is turned off for every table.

您可以为单个表打开和关闭闪回存档。 默认情况下，每个表都关闭闪回归档。

Flashback Database
At the physical level, Oracle Flashback Database provides a more efficient data protection alternative to database point-in-time recovery (DBPITR). If the current data files have unwanted changes, then you can use the RMAN command FLASHBACK DATABASE to revert the data files to their contents at a past time. The end product is much like the result of a DBPITR, but is generally much faster because it does not require restoring data files from backup and requires less redo than media recovery.

在物理级别，Oracle闪回数据库为数据库时间点恢复（DBPITR）提供了更高效的数据保护。 如果当前数据文件有不需要的更改，则可以使用RMAN命令FLASHBACK DATABASE将数据文件还原到其过去的内容。 最终产品非常类似于DBPITR的结果，但通常速度更快，因为它不需要从备份恢复数据文件，并且相比介质恢复只需要少量的重做。

Flashback Database uses flashback logs to access past versions of data blocks and some information from archived redo logs. Flashback Database requires that you configure a fast recovery area for a database because the flashback logs can only be stored there. Flashback logging is not enabled by default. Space used for flashback logs is managed automatically by the database and balanced against space required for other files in the fast recovery area.

闪回数据库使用闪回日志访问过去版本的数据块和来自归档重做日志的一些信息。 闪回数据库要求您为数据库配置快速恢复区域，因为闪回日志只能存储在那里。 默认情况下未启用闪回记录。 用于闪回日志的空间由数据库自动管理，并与快速恢复区域中其他文件所需的空间进行平衡。

Oracle Database also supports restore points along with Flashback Database and backup and recovery. A restore point is an alias corresponding to a system change number (SCN). You can create a restore point at any time if you anticipate needing to return part or all of a database to its contents at that time. A guaranteed restore point ensures that you can use Flashback Database to return a database to the time of the restore point.

Oracle数据库还支持闪回数据库和恢复点的备份和恢复。 恢复点是对应于系统更改号（SCN）的别名。 如果您预计需要将部分或全部数据库返回到其内容，则可以随时创建恢复点。 保证的还原点确保您可以使用Flashback Database将数据库返回到还原点的时间。

About Data Recovery Advisor
Oracle Database includes a Data Recovery Advisor tool that automatically diagnoses persistent data failures, presents appropriate repair options, and executes repairs at your request. Data Recovery Advisor provides a single point of entry for Oracle backup and recovery solutions. You can use Data Recovery Advisor through Oracle Enterprise Manager or through the RMAN command-line client.

Oracle数据库包含一个数据恢复顾问工具，可自动诊断持久性数据故障，提供适当的修复选项，并根据您的请求执行修复。 数据恢复顾问为Oracle备份和恢复解决方案提供单一入口点。 您可以通过Oracle Enterprise Manager或通过RMAN命令行客户端使用Data Recovery Advisor。

A database failure usually manifests itself as a set of symptoms: error messages, alerts, trace files and dumps, and failed data integrity checks. Data Recovery Advisor automatically diagnoses and informs you of these failures. For Data Recovery Advisor, a failure is a persistent data corruption that can be directly mapped to a set of repair actions. Each failure has a status of open or closed. Each failure also has a priority of critical, high, or low.

数据库故障通常表现为一组症状：错误消息，警报，跟踪文件和转储，以及失败的数
据完整性检查。 数据恢复顾问自动诊断并通知您这些故障。 对于数据恢复顾问，失败是持久数据损坏，可以直接映射到一组修复操作。 每个故障具有打开或关闭的状态。 每个故障还具有危险，高或低的优先级。

Failures are detected by data integrity checks, which are diagnostic procedures executed to assess the health of the database or its components. If a data integrity check reveals a failure, then Data Recovery Advisor automatically assesses the effect of a set of failures and maps it to a set of repair options. Usually, Data Recovery Advisor presents both automated and manual repair options.

通过数据完整性检查来检测故障，这些检查是为了评估数据库或其组件的运行状况而执行的诊断过程。 如果数据完整性检查显示失败，则数据恢复顾问会自动评估一组故障的影响，并将其映射到一组修复选项。 通常，数据恢复顾问提供自动和手动修复选项。

Data Recovery Advisor determines the best automated repair option and its effect on the database. The repair option may include repairs such as data file restore and recovery, media recovery, Flashback Database, and so on. Before presenting an automated repair option, Data Recovery Advisor validates it for the specific environment and the availability of media components required to complete the proposed repair.

数据恢复顾问确定最佳的自动修复选项及其对数据库的影响。 修复选项可以包括诸如数据文件恢复和恢复，介质恢复，闪回数据库等的修复。 在提供自动修复选项之前，数据恢复顾问会根据特定环境以及完成建议修复所需的介质组件的可用性来进行验证。

If you choose an automated repair option, then RMAN coordinates sessions on the Oracle Database to perform the repair for you. The Data Recovery Advisor tool verifies the repair success and closes the appropriate failures.

如果选择自动修复选项，则RMAN会在Oracle数据库上协调会话以执行修复。 数据恢复顾问工具会验证修复成功并关闭相应的故障。