12. Rerun all the commands from Step 9.
P AR T III
Two-Minute Drill
Restore Dropped Tables from the Recycle Bin
• Dropped tables can be restored with FLASHBACK TABLE <table_name> TO
BEFORE DROP, if the space they occupy has not been reused.
• Flashback drop cannot function if the owning schema or the tablespace has
been dropped.
• Dependent indexes, triggers, and grants will also be restored, as will all
constraints except foreign key constraints.
• Dropped tables can be viewed, but you cannot perform DML or DDL against
them.
• Space occupied by dropped objects does not impact on quotas or trigger space
shortage alerts.
Perform Flashback Query
• Flashback Query relies on data in the undo segments.
• The AS OF clause must be used to give access to the pseudocolumns that
identify different versions of a row.
• The point to which the flashback should go can be specified as a timestamp or
an SCN.
Use Flashback Transaction
• The SELECT ANY TRANSACTION and FLASHBACK ANY TABLE privileges
must be granted to users who will use the flashback transaction facility.
• Transactions can be viewed in the FLASHBACK_TRANSACTION_QUERY
view, the UNDO_SQL column being a construction of a statement to reverse
the change.
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• A transaction flashback may not succeed, because of conflicts caused
(typically) by constraint violations.
Perform Flashback Table Operations
• A table flashback attempts to reverse all changes applied to one or more tables.
• The necessary changes, no matter over what time or how many tables, are
applied as one transaction.
• Row movement must be enabled on tables before attempting a table flashback.
Configure and Monitor Flashback Database and Perform
Flashback Database Operations
• A database flashback is functionally equivalent to an incomplete recovery.
• Flashback logs exist in the flash recovery area, and the flashback buffer exists
in the shared pool; both are automatically managed.
• A database flashback operation is accomplished in mount mode and
terminated with a RESETLOGS.
• Both flashback log files and redo log files are needed during a flashback. The
database must be running in archivelog mode.
Set Up and Use a Flashback Data Archive
• An archive exists in one or more tablespaces.
• Once a table is nominated for archiving, some DDL commands will no longer
be possible.
• The FBDA background process captures before-images of rows and saves them to
the archive, and purges the archive of data that has passed its retention period.
Self Test
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