Oracle Flashback

1.Flashback query

Depend on:content in undo tablespace

1.1Base syntax:

   1: SELECT ... FROM ... AS OF TIMESTAMP TO_TIMESTAMP('...','yyyy-mm-dd hh34:mi:ss')

1.2Flashback table

Hints:Row movement must be enabled on the tables needed to be flashback.

   1: ALTER TABLE XXX ENABLE ROW MOVEMENT

Use Flashback table

   1: FLASHBACK TABLE XXX TO TIMESTAMP('...','yyyy-mm-dd hh34:mi:ss')

Warning:If there exist foreign key constraint,maybe operator would flashback not only one table

1.3Flashback version query

Base:Virtual columns:VERSIONS_STARTSCN,VERSIONS_ENDSCN,VERSIONS_STARTTIME,VERSIONS_ENDTIME,

VERSIONS_XID(type RAW,transaction ID),VERSIONS_OPERATIONS(INSERT I,DELETE D,UPDATE U)

Syntax:

   1: SELECT 

   2: column1,column2,...,

   3: VERSIONS_XID,VERSIONS_STARTTIME,VERSIONS_ENDTIME,VERSIONS_OPERATION 

   4: FROM  

   5: VERSIONS BETWEEN TIMESTAMP TIMESTAMP1 AND 

   6: TIMESTAMP2 

   7: WHERE 

1.4Flashback transaction

Base:Based on flashback version query.

The dbms will provide the undo SQL commands to flashback the specified transaction operations

Involved Data Dictionary Table:FLASHBACK_TRANSACTION_QUERY(XID,…,OPERATION,ROWID,UNDO_SQL)

Flashback transaction manually(Get the undo_sql and execute it yourself):

   1: SELECT OPERATION,UNDO_SQL FROM FLASHBACK_TRANSACTION_QUERY WHERE XID=hextoraw('xxxxxxxxxxxxxxx');

Flashback transacion with package of dbms:

   1: execute 

   2: dbms_flashback.transaction_backout

   3: (-numtxns=>2,-xids=sys.xid_array('0900010059100000','02000700920F0000',-options=>dbms_flashback.cascade);

2.Flashback deletion(drop only)

Depend on:recyclebin(renaming table)

2.1Performing flashback deletion

P1:flashback drop feature is enabled default.So tables dropped by users are put into recycle bin.

You should confirm it so that log in as the owner of table and "show recyclebin"

P2:

   1: flashback table xxx to before drop

3.Flashback Database

Depend on:flashback log

3.1Enable flashback database feature

P1:Set FRA location

P2:Set the size of FRA

P3:Set flashback retention

P4:Restart Database instance to mount

P5:

   1: ALTER DATABASE FLASHBACK ON

P6:

   1: ALTER DATABASE OPEN

3.2Flashback Database

P1:Restart database instance to mount

P2:

   1: FLASHBACK DATABASE TO TIMESTAMP/SCN XXX

P3:

   1: ALTER DATABASE OPEN RESETLOGS

4.Flashback Data Archive(FDA)/Total Recall

Base:

Create a tablespace to store flashback log data so that users can execute flashback query successfully

during retention period.

4.1Enable FDA on a table

P1:Create a tablespace

   1: CREATE TABLESPACE FDA DATAFILE 'fda1.dbf' SIZE 10M

P2:Create a fda identifier and set retention time

   1: CREATE FLASHBACK ARCHIVE fla1 TABLESPACE FDA RETENTION 7 year;

P3:Grant appropriate privilege to fdauser

   1: GRANT FLASHBACK ARCHIVE ON fla1 TO 

P4:Enable FDA on tables

   1: ALTER TABLE xx FLASHBACK ARCHIVE fla1

4.2Disable FDA on a table

P1:

   1: ALTER TABLE xxx.xxx NO FLASHBACK ARCHIVE

P2:

   1: DROP FLASHBACK ARCHIVE fla1;