There are four basic objects in a LogMiner configuration that you should be familiar with: the source database, the mining database, the LogMiner dictionary, and the redo log files containing the data of interest:
LogMiner uses the dictionary to translate internal object identifiers and data types to object names and external data formats. Without a dictionary, LogMiner returns internal object IDs and presents data as binary data.
For example, consider the following SQL statement:
INSERT INTO HR.JOBS(JOB_ID, JOB_TITLE, MIN_SALARY, MAX_SALARY) VALUES('IT_WT','Technical Writer', 4000, 11000);
Without the dictionary, LogMiner will display:
insert into "UNKNOWN"."OBJ# 45522"("COL 1","COL 2","COL 3","COL 4") values (HEXTORAW('45465f4748'),HEXTORAW('546563686e6963616c20577269746572'), HEXTORAW('c229'),HEXTORAW('c3020b'));
The redo log files contain the changes made to the database or database dictionary.