In this chapter, you
will see how to use the following features to enhance the availability of your database:
Flashback Drop
Flashback Database
LogMiner
Online object-reorganization options
Flashback Drop relies on a construct introduced in Oracle Database 10g, the recycle bin,
which behaves much like the recycle bin on a Windows-based computer: if there is enough room
in the tablespace, dropped objects can be restored to their original schema with all indexes and
constraints intact. Flashback Database relies on data stored in the Flash Recovery Area, a new
storage area also introduced in Oracle Database 10g. LogMiner, available since Oracle9i, relies
on archived redo log files to see the changes made to tables, indexes, and other database structures
(DDL operations) over time.
Recovering Dropped Tables Using
Flashback Drop
When you drop a table (and its associated indexes, constraints, and nested tables), Oracle does
not immediately release the table??™s disk space for use by other objects in the tablespace. Instead,
the objects are retained in the recycle bin until purged by the owner or the space occupied by the
dropped objects is needed for new objects.
In this example, consider the AUTHOR table, defined as follows:
SQL> describe AUTHOR
Name Null? Type
------------------ -------- ----------------------------
AUTHORNAME NOT NULL VARCHAR2(50)
COMMENTS VARCHAR2(100)
Now, assume that the table is dropped accidentally.
Pages:
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751