Learn How To Use LogMiner(Base Concepts)

Based on:

　　All changes made to user data or to the database dictionary are recorded in the Oracle redo log files so that database recovery operations can be performed.Pinpointing when a logical corruption to a database, such as errors made at the application level and so on.

LogMiner Benefits:

• Pinpointing when a logical corruption to a database, such as errors made at the application level.
• Determining what actions you would have to take to perform fine-grained recovery at the transaction level.
• Performance tuning and capacity planning through trend analysis.
• Performing postauditing. LogMiner can be used to track any data manipulation language (DML) and data definition language (DDL) statements executed on the database, the order in which they were executed, and who executed them.

Four basic objects:

• The source database is the database that produces all the redo log files that you want LogMiner to analyze.
• The mining database is the database that LogMiner uses when it performs the analysis.
• The mining database is the database that LogMiner uses when it performs the analysis. Without a dictionary, LogMiner returns internal object IDs and presents data as binary data.

　　　　For example, consider the following the 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.

Sample LogMiner Database Configuration

Three Work Mode:

• Using the Online Catalog

　　　　To direct LogMiner to use the dictionary currently in use for the database, specify the online catalog as your dictionary source when you start LogMiner.

• Extracting a LogMiner Dictionary to the Redo Log Files

　　　　Extract a LogMiner dictionary to the redo log files and transfer it to the Minidatabase with Archivelog files,then you can analyze the logs on Minidatabase with

        Logminer.

• Extracting the LogMiner Dictionary to a Flat File

　　　　Extract a dictionary to a flat file and transfer it to the Minidatabase with Archivelog files.

 

 

 

　　(To be continue``````《Learn How To Use LogMiner(Practice)》)