Introduction to Oracle's Flashback table

Because the rowid of the data being flashback back may change.

Sql> CREATE TABLE TT (ID int,name varchar2 (4000)) tablespace users;

Table has been created.

Sql> ALTER TABLE TT Pctfree 50;

The table has changed.

Sql> INSERT INTO TT values (1,rpad (' A ', 4000, ' + '));

1 lines have been created.

Sql> commit;

Submit completed.

Sql> INSERT INTO TT values (2,rpad (' B ', 4000, ' + '));

1 lines have been created.

Sql> commit;

Submit completed.

Sql> Select Id,substr (name,1,1), rowid from TT;

ID SU ROWID

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

1 a AAAC+FAAEAAAGT3AAA

2 b aaac+faaeaaagt4aaa

sql> analyze table TT compute statistics;

The table is parsed.

Sql> Delete from TT;

2 rows have been deleted.

Sql> commit;

Submit completed.

Sql> INSERT INTO TT values (3,rpad (' C ', 4000, ' + '));

1 lines have been created.

Sql> commit;

Submit completed.

--when inserting a id=3, it's obvious that you have repeatedly used the ROWID to delete id=1

Sql> Select Id,substr (name,1,1), rowid from TT;

ID SU ROWID

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

3 C AAAC+FAAEAAAGT3AAA

Sql> select Current_scn from V$database;

Current_scn

-----------

379146

Sql> set time on

11:58:34 sql> Select ID from TT as of SCN 379146;

Id

----------

3

11:58:37 sql> Select ID from TT as of SCN 379140;

Id

----------

3

11:58:42 sql> Select ID from TT as of SCN 379130;

Id

----------

3

11:58:47 sql> Select ID from TT as of SCN 379100;

Id

----------

1

2

11:58:52 sql> Flashback table TT to SCN 379100;

Flashback table TT to SCN 379100

*

Line 1th Error:

ORA-08189: Cannot flash back the table because row move is not enabled

11:59:42 sql> ALTER TABLE TT enable row movement;

The table has changed.

11:59:57 sql> Flashback table TT to SCN 379100;

Flash back complete.

--tt was flashback back rowID has changed, which is why flashback

Table needs to enable row movement, in the normal table

The rowid of the data is definitely not to be changed.

12:00:25 sql> Select Id,substr (name,1,1), rowid from TT;

ID SU ROWID

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

2 b Aaac+faaeaaagt3aab

1 a AAAC+FAAEAAAGT4AAA

12:00:35 sql>

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