Here For you Guys

1. To: Resp. Khursheed Asghar
Dept. of IT.
UE Okara Campus.
From:
Sohaib Saleem Ch - 3008
Abdur-Rehman Malik -3030

2. Overview of Flashback
Technology
 .

3. Oracle Database Flashback
 Oracle Database Flashback Technologies are a unique
and rich set of data recovery solutions that enable
reversing human errors by selectively and efficiently
undoing the effects of a mistake.
 Before Flashback, it might take minutes to damage a
database but hours to recover it.
 Oracle Flashback Technology is a group of Oracle
Database features that that let you view past states of
database objects or to return database objects to a
previous state without using point-in-time media
recovery.

4. What is Flashback
Technology?
 .

5. What is Flashback Technology?
 Oracle Flashback Technology provides a set of features
available on 9i or higher version that support viewing
and rewinding data back and forth in time to recover
from Logical Corruptions while the database is online.
 To view the past state of database objects.
 To return a database object to a previous state without
point-in-time media recovery.
 Uses automatic undo management.
 Flashback technology basically handle the errors
produced by human

6. Flashback Technology?
 Data loss and Recovery
 Human error
 Logical data corruption
 Time consuming recovery
 Oracle flashback technology reduced recovery
time from hours to minutes
 Example

7. Why we use Flashback?
 .

8. Why?
 Execute queries that return past data(history’s data)
 Execute queries that return metadata that shows a
detailed history of changes to the database
 Recover data to a previous point in time
 Automatically track and archive transactional
Changes data
 Roll back a transaction and its dependent
 transactions while the database remains online
 Note: we need to know what was the data in history, do
why we need to go back to historical data.

9. Pre-requisites:
 .

10. Pre-requisites:
 Database Must be in ARCHIVE LOG mode
 Execute permission on DBMS_FLASHBACKpackage
 SELECT ANY TRANSACTION privilege
 FLASHBACK ANY TRANSACTION privilege
 CREATE TABLE privilege
 Enable SUPPLEMENTAL LOG DAT A
 Set FLASHBACK_ON

11. Different ways to track
and fix logical corruption
 .

12. 1. Flashback query:
 To view the snapshot of records all given time all
command executed between time.
 Oracle Flashback Query feature lets you specify a target
time and then run queries against your database, viewing
results as they would have appeared at that time.
 query any data at some point-in-time in the past. This
powerful feature can be used to view and logically
reconstruct corrupted data that may have been deleted or
changed inadvertently.
 retrieves data as it existed at some time in the past.
 E.g:
 select count(*) from COURSE as of timestamp sysdate -
5/(24*60);

13. 2. Flashback version Query
 To see the transaction which has been perform on a
table.
 Oracle Flashback Version Query lets you view all the
versions of all the rows that ever existed in one or more
tables in a specified time interval.
 E.g:
 Select versions_starttime, versions_endtime,
versions_xid, from the COURSE versions between
timestamp minvalue and maxvalue;

14. 3. Flashback transaction query:
 Used to recover the transaction as per “xid” number
which we have got through previous version query.
 Oracle Flashback Transaction Query lets you view
changes made by a single transaction, or by all the
transactions during a period of time.
 see all the changes made by a specific transaction,
useful when an erroneous transaction changed data in
multiple rows or tables.
 E.g:
 Select undo_sql from flashback_transation_query
where xid= “ xid_no.”;

15. 4. Flashback table
 Oracle Flashback Table returns a table to its state at a
previous point in time.
 easily recover tables to a specific point-in-time, useful
when a logical corruption is limited to one or a set of
tables instead of the entire database.
 E.g:
 FLASHBACK TABLE ftest TO TIMESTAMP
TO_TIMESTAMP('05-02-2008 10:22:45','DD-MM-
YYYY HH:MI:SS');

16. 5.Flashback Drop:
 Recover an accidentally dropped table. It restores the dropped
table, and all of its indexes, constraints, and triggers, from the
Recycle Bin (a logical container of all dropped objects).
 reverses the effects of a DROP TABLE statement.
 E.g:
 select OBJECT_NAME,ORIGINAL_NAME from user_recyclebin;
 show recyclebin;
 SELECT * FROM "BIN$RWou3ZujSqXgQBQKHZhmkg==$0";
 FLASHBACK TABLE fsbtest.ftest_drop TO BEFORE DROP;
 FLASHBACK TABLE "BIN$RWou3ZujSqXgQBQKHZhmkg==$0"
TO BEFORE DROP RENAME TO fsbtest.ftest1;

17. 6. Flashback Database
 Flashback Database provides a more efficient
alternative to database point-in-time recovery.
 restore the entire database to a specific point-in-time,
using Oracle-optimized flashback logs, rather than via
backups and forward recovery.
 E.g:
 select NAME,FLASHBACK_ON from v$database;
 SELECT CURRENT_SCN FROM V$DATABASE;

18. THANKS