Also it is possible to bring a single table back in time. Flashback database is different from traditional point in time recovery. To Flashback a database, Oracle uses older block images to back out changes to the database, what means that the oracle blocks are being overwritten for its before images to bring the database back in time. If flashback database feature is enabled, during normal database operation, Oracle creates the Flashback logs, where the before image of the database blocks is stored previously to applying any change in this database blocks.
Oracle automatically creates, deletes, and resizes Flashback logs in the flash recovery area. You only need to be aware of Flashback logs for monitoring performance and deciding how much disk space to allocate to the flash recovery area for Flashback logs.
Flashback Database is not true media recovery, because it does not involve restoring physical files. Note that, you cannot manually delete the flashback logs, you need to turn flashback database off to delete the flashback logs. You are commenting using your WordPress. You are commenting using your Google account. You are commenting using your Twitter account. You are commenting using your Facebook account. Notify me of new comments via email. Flashback Database uses flashback logs to access past versions of data blocks, as well as some information from the archived redo log.
To have the option of using Flashback Database to repair your database, you must either configure your database to generate flashback logs, or use the related capability of guaranteed restore points to protect the contents of your database at a fixed point in time, such as immediately before a risky database change. Oracle Database Concepts and Oracle Database Administrator's Guide for more information on undo data and automatic undo management. Skip Headers. However, there are some disadvantages to point-in-time recovery: You cannot return only selected objects to their earlier state, only the entire database.
Your entire database is unavailable during the database point-in-time recovery process. Note: If you know that unwanted database changes are extensive but confined to certain tablespaces in your database, tablespace point-in-time recovery TSPITR can return a subset of your tablespaces to an earlier SCN while the unaffected tablespaces of your database continue to be available.
They can also be used to investigate past states of Most Flashback Technology features operate at the logical level, viewing and manipulating database objects, as follows: Oracle Flashback Query lets you specify a target time and then run queries against your database, viewing results as they would have appeared at that time. All rights reserved. Book List. Master Index. Contact Us. How far back can we flash back our database?
It seems that these two parameters are not normally set to a large number. They are probably set to a relatively smaller number with the consideration of disk space management. Rolling back our database incrementally all the way back to the point in time 2 weeks ago or a month ago will probably takes much longer than restoring and recovering the database with a backupset and relatively a small set of archived logs.
I guess that it is good to have both of them in place. Posted by Hoon Lee at PM. Labels: Oracle.
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