LogMiner allows you to make queries based on actual changes made to table data. This allows you to analyze system behavior and to perform auditing tasks.
Subprocedures:
ADD_LOGFILE   Add a file to the existing or newly created list of
              archive files to process. 
START_LOGMNR  Initialize the LogMiner utility. 
END_LOGMNR    Finish a LogMiner session. 
MINE_VALUE Function
              This function may be called for any row returned from
              V$LOGMNR_CONTENTS to retrieve the undo or redo column value
              of the column specified by the column_name input parameter to this function. 
COLUMN_PRESENT Function
              This function may be called for any row returned from
              V$LOGMNR_CONTENTS to determine if undo or redo column values exist
              for the column specified by the column_name input parameter to this function. 
For full documentation of the packaged procedures above see the Oracle Manual:
"Oracle9i Supplied PL/SQL Packages and Types Reference"
or the book Oracle Built in Packages by Steven Feuerstein et al
Related Views:
V$LOG 
V$LOGFILE 
V$LOGHIST 
V$LOGMNR_CONTENTS 
V$LOGMNR_DICTIONARY 
V$LOGMNR_LOGS 
V$LOGMNR_PARAMETERS 
V$LOG_HISTORY