You can use the Oracle LogMiner utility to enable you to query redo log files through a SQL interface.
# vi initmydb.ora -- Then add the following line and save the file.
You can specify the redo log files as following examples with the mount or nomount option of startup.
-- for new log file or the first one.
-- for adding an additional log file.
-- for removing a log file.
To read the log file, you need to do the following query.
To determine which tables were modified in the range of time.
To determine who drop any objects.
To end the log miner.