[bbk4485]第二章Flashback Database 00

Objectives

After completing this lesson,you should be able to:

  • Describe Flashback technology
  • Configure Flashback Database
  • Perform Flashback Database operations
  • Monitor Flashback Database 

Flashback Technolog:Benefits

  • Te Flashback technology is a revolutionary advantage in recovery.
  • Traditional recovery techniques are slow.
    • The entire database or a file(not just the incorrect data) has to be restored.
    • Every change in the database log must be examined.
  • Flashback is fast
    • Changes are indexed by row and by transaction
    • Only the changed data is restred.
  • Flashback commands are easy.
    • No complex mulitple-step procedures are involved.

Flashsback Technology

Object Level Scenario Examples Flashback Technology Depends On Affects Data
Database

Truncate table;

Undesired multiple changes made

Database Flashback logs TRUE
Table Drop table Drop Recycle bin TRUE
Update with the wrong WHERE clause Table Undo data TRUE
Compare current data with data from past Query Undo data FALSE
Compare version of a row Versoin Undo data FALSE
Keep histrical transaction data Data Archive Undo data TRUE
Transaction Investigate and back out suspect transactions Transaction Undo/redo from Archive logs TRUE

 

 

posted @ 2013-05-15 12:12  ArcerZhang  阅读(133)  评论(3编辑  收藏  举报