Flashback technology in oracle database

Rameshdba.com

 Summary: in this tutorial, you will learn what is Flashback technology in an Oracle Database instance.


it is Used to recover our database from accidental statement failure suppose someone deleted the table, using flash back we can get it back.


Here we are going to learn table level first!


connect the database:

[oracle@oracle ~]$ sqlplus / as sysdba


SQL*Plus: Release 12.1.0.2.0 Production on Sat Aug 12 20:38:02 2023

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

Connected to:

Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production

With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options


NAME      OPEN_MODE

--------- --------------------

PROD      READ WRITE


Check the flashback status in database:


SQL> select flashback_on from v$database;


FLASHBACK_ON

------------------

NO



Flashback should be on status  do it using following:

SQL> alter database flashback on;

Database altered.



Connect the user and drop the schema.
SQL>  select * from tab;

TNAME            TABTYPE  CLUSTERID
---------------- ------- ----------
BONUS            TABLE
DEPT             TABLE
EMP              TABLE
SALGRADE         TABLE




SQL> drop table EMP;

Table dropped.



SQL> select * from tab;

TNAME            TABTYPE  CLUSTERID
---------------- ------- ----------
SALGRADE         TABLE
DEPT             TABLE
BONUS            TABLE
BIN$Arw7D/KXD2bg TABLE
YwoKFKx9PA==$0




SQL> select OBJECT_NAME,ORIGINAL_NAME,DROPTIME,DROPSCN,TS_NAME from user_recyclebin;


OBJECT_NAME          ORIGINAL_NAME        DROPTIME               DROPSCN TS_NAME
-------------------- -------------------- ------------------- ---------- ------------------------------
BIN$Arw7D/KXD2bgYwoK EMP                  2023-08-12:20:40:33    6252832 USERS
FKx9PA==$0

BIN$Arw7D/KWD2bgYwoK BIN$Ahyq3tRoEAXgYwoK 2023-08-12:20:40:33    6252826 USERS
FKx9PA==$1           FKzbXg==$0




SQL> flashback table emp to before drop;

Flashback complete.



SQL> select * from tab;

TNAME            TABTYPE  CLUSTERID
---------------- ------- ----------
BONUS            TABLE
DEPT             TABLE
EMP              TABLE
SALGRADE         TABLE




SQL> select * from emp;

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7369 SMITH      CLERK           7902 17-DEC-80        800                    20
      7499 ALLEN      SALESMAN        7698 20-FEB-81       1600        300         30
      7521 WARD       SALESMAN        7698 22-FEB-81       1250        500         30
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7654 MARTIN     SALESMAN        7698 28-SEP-81       1250       1400         30
      7698 BLAKE      MANAGER         7839 01-MAY-81       2850                    30
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
      7839 KING       PRESIDENT            17-NOV-81       5000                    10
      7844 TURNER     SALESMAN        7698 08-SEP-81       1500          0         30
      7876 ADAMS      CLERK           7788 23-MAY-87       1100                    20

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7900 JAMES      CLERK           7698 03-DEC-81        950                    30
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20
      7934 MILLER     CLERK           7782 23-JAN-82       1300                    10

14 rows selected.




SQL> Thank you!

Thanks
Rameshbabu P



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