DBPITR:Determine the target time_determine the time-优快云博客

本文介绍了如何使用 Flashback 特性确定数据库逻辑损坏发生的时间，并通过查询 V$LOG_HISTORY 来确定归档日志中包含的目标 SCN 对应的日志序列号，以便进行精确的数据恢复。

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■ Determine the target time, SCN, restore point, or log sequence number that should end recovery.

The Flashback Query, Flashback Version Query and Flashback Transaction Query features can help you identify when the logical corruption occured.

You can also examine the alert.log for information that may help you determine the time of the event from which you need to recover.

lternatively, you can determine the log sequence number that contains the target SCN, and then recover through that log.

For example, query V$LOG_HISTORY to view the logs that have been archived.
RECID STAMP THREAD# SEQUENCE# FIRST_CHAN FIRST_TIM NEXT_CHANG
---------- ---------- ---------- ---------- ---------- --------- ----------
1 344890611 1 1 20037 24-SEP-04 20043
2 344890615 1 2 20043 24-SEP-04 20045
3 344890618 1 3 20045 24-SEP-04 20046

If, for example, you discover that a user accidentally dropped a tablespace at 9:02
a.m., then you can recover to 9 a.m., just before the drop occurred. You will lose all
changes to the database made after that time.

■ If you are using a target time expression instead of a target SCN, then make sure that the time format environment variables are set appropriately before invoking RMAN.

The following are sample Globalization Support settings:
NLS_LANG = american_america.us7ascii
NLS_DATE_FORMAT="Mon DD YYYY HH24:MI:SS"