Log Miner can help when questions such as the following come up: What was changed? Who changed it? And in what order?
When unauthorized people change data, they may assume that the record does not retain all changes if that information isn't viewable at the application level. There is a record of all changes that are logged, but it takes time and trouble to find that information.
The tool most often used is the PL/SQL package DBMS_LOGMNR, but the GUI Interface called Log Miner Viewer has been added to the OEM. There are quite a few examples in the Oracle Database Utilities Guide of how to use this utility for both the browser-based and PL/SQL versions. We will concentrate on when and how to find the data to restore.
You already should have a good understanding of the database structures that include the undo and redo logs: undo is generated when an end user starts changing data and redo is generated after the commit. Each is written to their own set of files...
