Turn Oracle Database Flashback On

June 1, 2008  |  dba, security

FlashBack is a feature introduced in Oracle9i and improved (and hyped) in Oracle10g. Oracle9i introduced Flashback Query to provide a simple, powerful and completely non-disruptive mechanism for recovering from human errors. It allows users to view the state of data at a point in time in the past without requiring any structural changes to the database. Oracle Database 10g extended the Flashback Technology to provide fast and easy recovery at the database, table, row, and transaction level. Flashback Technology revolutionizes recovery by operating just on the changed data.

Once you enable the flashback database feature, at regular intervals, a new process RVWR (RecoveryWriter) copies images of each altered block in the datafiles from memory (flashback buffer) to the new flashback logs stored in the flashback recovery area.

So, let’s enable Flashback Database. The steps are…

1 – Check that you have your database in archivelog mode.

2 - Do this:
[sql]
shutdown immediate;
startup mount exclusive;
alter system set DB_RECOVERY_FILE_DEST='/opt/oracle/flash_recovery_area' scope=spfile;
alter system set DB_RECOVERY_FILE_DEST_SIZE=4G scope=spfile;
alter database flashback on;
shutdown;
startup;

It’s very important that before the last shutdown you set both flash recovery area parameters (DB_RECOVERY_FILE_DEST and DB_RECOVERY_FILE_DEST_SIZE). If you set only one your database won’t start and you’ll have to take a copy of an initialization parameter file (init.ora) to startup the database


1 Comment


  1. This is a great tutorial, I am a beginner to Access and I need to build a survey database for the company i work for. Can you tell me how to build a database to score a survey?

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