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Oracle10g Flashback Technology

Oracle10g Flashback Technology. New Features for recoverability. Objectives. At the end of this module the student will understand the following tasks and concepts. Understand the new Flashback Technologies in Oracle10g. Understand how to use Flashback Technology. Overview. Flashback Query

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Oracle10g Flashback Technology

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  1. Oracle10g Flashback Technology New Features for recoverability

  2. Objectives At the end of this module the student will understand the following tasks and concepts. • Understand the new Flashback Technologies in Oracle10g. • Understand how to use Flashback Technology.

  3. Overview • Flashback Query • Flashback Table • Flashback Drop • Flashback Database

  4. Flashback Query • Allows you to access data from the past • Flashback Query • Query data as it was in the past • Flashback Version Query • View all versions of data as it existed in the past • Flashback Transaction Query • View transactional data history • Uses UNDO tablespace • You can only recover to UNDO_RETENTION period

  5. Flashback Query • Query data at a time in the past (as far back as UNDO_RETENTION) • Select SELECT * FROM scott.emp AS OF TIMESTAMP TO_TIMESTAMP('2004-05-16 08:00:00', 'YYYY-MM-DD HH:MI:SS') WHERE ename = 'SCOTT'; • Populate INSERT INTO scott.emp (SELECT * FROM scott.emp AS OF TIMESTAMP TO_TIMESTAMP('2004-05-16 08:00:00', 'YYYY-MM-DD HH:MI:SS') WHERE ename = 'SCOTT');

  6. Flashback Version Query • Used to retrieve version information SELECT SUBSTR(versions_startscn,1,10) AS "StartSCN", SUBSTR(versions_endscn,1,10) AS "EndSCN", SUBSTR(versions_starttime,1,25) AS "StartTime", SUBSTR(versions_endtime,1,25) AS "EndTime", SUBSTR(versions_xid,1,20) AS "XID", SUBSTR(versions_operation,1,20) AS "Operation", ename, sal FROM scott.emp VERSIONS BETWEEN TIMESTAMP TO_TIMESTAMP('2004-05-16 11:00:00', 'YYYY-MM-DD HH24:MI:SS') AND TO_TIMESTAMP('2004-05-16 11:20:00', 'YYYY-MM-DD HH24:MI:SS') WHERE ename='MILLER';

  7. Flashback Version Query • Output StartS EndSCN StartTime EndTime XID O ENAME SAL ------ ------ ------------------------- ------------------------- ---------------- - ---------- ---------- 462855 16-MAY-04 11.18.03 AM 0300260084060000 U MILLER 1500 462680 462855 16-MAY-04 11.13.55 AM 16-MAY-04 11.18.03 AM 010022006A020000 U MILLER 1400 462680 16-MAY-04 11.13.55 AM MILLER 1300

  8. Flashback Transaction Query • Similar to version except by transaction and not data SELECT xid, SUBSTR(logon_user,1,20) AS "User", SUBSTR(operation,1,8) AS "Oper", SUBSTR(undo_sql,1,40) AS "UNDO SQL" FROM flashback_transaction_query WHERE xid IN (SELECT versions_xid FROM scott.emp VERSIONS BETWEEN TIMESTAMP TO_TIMESTAMP('2004-05-16 11:00:00', 'YYYY-MM-DD HH24:MI:SS') AND TO_TIMESTAMP('2004-05-16 11:55:00', 'YYYY-MM-DD HH24:MI:SS') WHERE ename='MILLER');

  9. Flashback Transaction Query • Output XID User Oper UNDO SQL ---------------- -------------------- -------- ---------------------------------------- 010022006A020000 SYSTEM UPDATE update "SCOTT"."EMP" set "SAL" = '1300' 010022006A020000 SYSTEM BEGIN 0300260084060000 SYSTEM UPDATE update "SCOTT"."EMP" set "SAL" = '1400' 0300260084060000 SYSTEM BEGIN 0B002C0018000000 SYSTEM UPDATE update "SCOTT"."EMP" set "SAL" = '1500' 0B002C0018000000 SYSTEM BEGIN

  10. Flashback Table • Restores a table as it was at some time in the past • Uses UNDO data SQL> FLASHBACK TABLE scott.emp TO TIMESTAMP TO_TIMESTAMP('2004-05-16 11:00:00', 'YYYY-MM-DD HH24:MI:SS'); 2 Flashback complete.

  11. Flashback Drop • Dropped Objects are saved in the Recycle Bin • Tables can be restored to before the drop SQL> FLASHBACK TABLE emp TO BEFORE DROP; • Recycle bin must be manually cleaned out via the PURGE command

  12. Flashback DropPURGE Command

  13. Flashback Database • Returns an entire database to a point in the past • Runs from within RMAN • Requires Flash Recovery Area • Requires full online RMAN backup + flashback logs • 1X – 3X the size of data file storage, depending on retention period

  14. Flashback DatabaseFlashback Command

  15. Review • What parameter controls the period of time you can “flash back” to? • What area can be used to restore objects after they are dropped? • What is the minimum size of the Flash Recovery Area relative to the database size? • Name two options for using Flashback Database?

  16. Summary • Flashback Query • Flashback Table • Flashback Drop • Flashback Database

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