What is the difference between undo and redo?

I'm confused about the term.

Fortunately they are documented:

Each Oracle database must have a method of maintenance of information allowing to make back, or cancel, the changes to the database. These > information consists of documents from the actions of the operations, especially before they committed. These records are collectively > as Cancel.

from: http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/undo.htm#sthref1466

The most crucial structure for recovery operations is the redo log, which consists of two or more pre-alloues files that store all changes > made to the database when they occur. Each instance of a data base Oracle has a newspaper again associated to protect data in the case of > a defect of the instance.

from: http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/onlineredo.htm#sthref850

Do some research here, and you'll get tons of info:
http://download.Oracle.com/docs/CD/B19306_01/index.htm

Tags: Database

Similar Questions

Maybe you are looking for