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Using Oracle Log Miner

Using Log Miner utility, you can query the contents of online redo log files and archived log files. Because LogMiner provides a well-defined, easy-to-use, and comprehensive relational interface to redo log files, it can be used as a powerful data audit tool, as well as a tool for sophisticated data analysis.

LogMiner Configuration

There are three basic objects in a LogMiner configuration that you should be familiar with: the source database,  the LogMiner dictionary, and the redo log files containing the data of interest:

LogMiner uses the dictionary to translate internal object identifiers and datatypes 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 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'));

LogMiner Dictionary Options

LogMiner requires a dictionary to translate object IDs into object names when it returns redo data to you. LogMiner gives you three options for supplying the dictionary:

Using the Online Catalog

Oracle recommends that you use this option when you will have access to the source database from which the redo log files were created and when no changes to the column definitions in the tables of interest are anticipated. This is the most efficient and easy-to-use option.

Extracting a LogMiner Dictionary to the Redo Log Files

Oracle recommends that you use this option when you do not expect to have access to the source database from which the redo log files were created, or if you anticipate that changes will be made to the column definitions in the tables of interest.

Extracting the LogMiner Dictionary to a Flat File

This option is maintained for backward compatibility with previous releases. This option does not guarantee transactional consistency. Oracle recommends that you use either the online catalog or extract the dictionary from redo log files instead.

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, as follows:

SQL> EXECUTE DBMS_LOGMNR.START_LOGMNR(-OPTIONS => DBMS_LOGMNR.DICT_FROM_ONLINE_CATALOG);

Extracting a LogMiner Dictionary to the Redo Log Files

To extract a LogMiner dictionary to the redo log files, the database must be open and in ARCHIVELOG mode and archiving must be enabled. While the dictionary is being extracted to the redo log stream, no DDL statements can be executed. Therefore, the dictionary extracted to the redo log files is guaranteed to be consistent (whereas the dictionary extracted to a flat file is not).

To extract dictionary information to the redo log files, use the DBMS_LOGMNR_D.BUILD procedure with the STORE_IN_REDO_LOGS option. Do not specify a filename or location.

SQL> EXECUTE DBMS_LOGMNR_D.BUILD(OPTIONS=> DBMS_LOGMNR_D.STORE_IN_REDO_LOGS);

Extracting the LogMiner Dictionary to a Flat File

When the LogMiner dictionary is in a flat file, fewer system resources are used than when it is contained in the redo log files. Oracle recommends that you regularly back up the dictionary extract to ensure correct analysis of older redo log files.

Set the initialization parameter, UTL_FILE_DIR, in the initialization parameter file. For example, to set UTL_FILE_DIR to use /oracle/database as the directory where the dictionary file is placed, enter the following in the initialization parameter file:

UTL_FILE_DIR = /oracle/database

Start the Database

SQL> startup

Execute the PL/SQL procedure DBMS_LOGMNR_D.BUILD. Specify a filename for the dictionary and a directory path name for the file. This procedure creates the dictionary file. For example, enter the following to create the file dictionary.ora in /oracle/database:

SQL> EXECUTE DBMS_LOGMNR_D.BUILD('dictionary.ora','/oracle/database/',
                       DBMS_LOGMNR_D.STORE_IN_FLAT_FILE);

Redo Log File Options

To mine data in the redo log files, LogMiner needs information about which redo log files to mine.

You can direct LogMiner to automatically and dynamically create a list of redo log files to analyze, or you can explicitly specify a list of redo log files for LogMiner to analyze, as follows:

Automatically

If LogMiner is being used on the source database, then you can direct LogMiner to find and create a list of redo log files for analysis automatically. Use the CONTINUOUS_MINE option when you start LogMiner.

Manually

Use the DBMS_LOGMNR.ADD_LOGFILE procedure to manually create a list of redo log files before you start LogMiner. After the first redo log file has been added to the list, each subsequently added redo log file must be from the same database and associated with the same database RESETLOGS SCN. When using this method, LogMiner need not be connected to the source database.

Example: Finding All Modifications in the Current Redo Log File

The easiest way to examine the modification history of a database is to mine at the source database and use the online catalog to translate the redo log files. This example shows how to do the simplest analysis using LogMiner.

Step 1 Specify the list of redo log files to be analyzed.

Specify the redo log files which you want to analyze.

SQL> EXECUTE DBMS_LOGMNR.ADD_LOGFILE( -
       LOGFILENAME => '/usr/oracle/ica/log1.ora',
       OPTIONS => DBMS_LOGMNR.NEW);
 
SQL> EXECUTE DBMS_LOGMNR.ADD_LOGFILE( -
       LOGFILENAME => '/u01/oracle/ica/log2.ora',
       OPTIONS => DBMS_LOGMNR.ADDFILE);

Step 2 Start LogMiner.

Start LogMiner and specify the dictionary to use.

SQL> EXECUTE DBMS_LOGMNR.START_LOGMNR(
       OPTIONS => DBMS_LOGMNR.DICT_FROM_ONLINE_CATALOG);

Step 3 Query the V$LOGMNR_CONTENTS view.

Note that there are four transactions (two of them were committed within the redo log file being analyzed, and two were not). The output shows the DML statements in the order in which they were executed; thus transactions interleave among themselves.

SQL> SELECT username AS USR, (XIDUSN || '.' || XIDSLT || '.' ||  XIDSQN) AS XID,SQL_REDO, SQL_UNDO FROM V$LOGMNR_CONTENTS WHERE username IN ('HR', 'OE');
USR    XID          SQL_REDO                        SQL_UNDO
----   ---------  ----------------------------------------------------
HR     1.11.1476  set transaction read write;
HR     1.11.1476  insert into "HR"."EMPLOYEES"(     delete from "HR"."EMPLOYEES" 
                  "EMPLOYEE_ID","FIRST_NAME",       where "EMPLOYEE_ID" = '306'
                  "LAST_NAME","EMAIL",              and "FIRST_NAME" = 'Mohammed'
                  "PHONE_NUMBER","HIRE_DATE",       and "LAST_NAME" = 'Sami'
                  "JOB_ID","SALARY",                and "EMAIL" = 'MDSAMI'
                  "COMMISSION_PCT","MANAGER_ID",    and "PHONE_NUMBER" = '1234567890'
                  "DEPARTMENT_ID") values           and "HIRE_DATE" = TO_DATE('10-JAN-2003
                ('306','Mohammed','Sami',         13:34:43', 'dd-mon-yyyy hh24:mi:ss') 
                  'MDSAMI', '1234567890',           and "JOB_ID" = 'HR_REP' and 
                  TO_DATE('10-jan-2003 13:34:43',   "SALARY" = '120000' and 
                  'dd-mon-yyyy hh24:mi:ss'),         "COMMISSION_PCT" = '.05' and
                  'HR_REP','120000', '.05',         "DEPARTMENT_ID" = '10' and
                  '105','10');                      ROWID = 'AAAHSkAABAAAY6rAAO';
OE     1.1.1484   set transaction read write;
OE     1.1.1484   update "OE"."PRODUCT_INFORMATION"  update "OE"."PRODUCT_INFORMATION" 
                  set "WARRANTY_PERIOD" =            set "WARRANTY_PERIOD" = 
                  TO_YMINTERVAL('+05-00') where      TO_YMINTERVAL('+01-00') where
                  "PRODUCT_ID" = '1799' and          "PRODUCT_ID" = '1799' and
                  "WARRANTY_PERIOD" =                "WARRANTY_PERIOD" = 
                  TO_YMINTERVAL('+01-00') and        TO_YMINTERVAL('+05-00') and
                  ROWID = 'AAAHTKAABAAAY9mAAB';      ROWID = 'AAAHTKAABAAAY9mAAB'; 
OE     1.1.1484   update "OE"."PRODUCT_INFORMATION"  update "OE"."PRODUCT_INFORMATION"
                  set "WARRANTY_PERIOD" =            set "WARRANTY_PERIOD" =
                  TO_YMINTERVAL('+05-00') where      TO_YMINTERVAL('+01-00') where
                  "PRODUCT_ID" = '1801' and          "PRODUCT_ID" = '1801' and
                  "WARRANTY_PERIOD" =                "WARRANTY_PERIOD" = 
                  TO_YMINTERVAL('+01-00') and        TO_YMINTERVAL('+05-00') and
                  ROWID = 'AAAHTKAABAAAY9mAAC';      ROWID ='AAAHTKAABAAAY9mAAC';
HR     1.11.1476  insert into "HR"."EMPLOYEES"(     delete from "HR"."EMPLOYEES"
                  "EMPLOYEE_ID","FIRST_NAME",       "EMPLOYEE_ID" = '307' and 
                  "LAST_NAME","EMAIL",              "FIRST_NAME" = 'John' and
                  "PHONE_NUMBER","HIRE_DATE",       "LAST_NAME" = 'Silver' and
                  "JOB_ID","SALARY",                "EMAIL" = 'JSILVER' and 
                  "COMMISSION_PCT","MANAGER_ID",    "PHONE_NUMBER" = '5551112222'
                  "DEPARTMENT_ID") values           and "HIRE_DATE" = TO_DATE('10-jan-2003
                  ('307','John','Silver',           13:41:03', 'dd-mon-yyyy hh24:mi:ss') 
                   'JSILVER', '5551112222',         and "JOB_ID" ='105' and
                                                   "DEPARTMENT_ID" 
                  TO_DATE('10-jan-2003 13:41:03',   = '50' and ROWID = 
                                                    'AAAHSkAABAAAY6rAAP'; 
                  'dd-mon-yyyy hh24:mi:ss'),
                  'SH_CLERK','110000', '.05',
                  '105','50');
OE     1.1.1484   commit;
HR     1.15.1481   set transaction read write;
HR     1.15.1481  delete from "HR"."EMPLOYEES"      insert into "HR"."EMPLOYEES"(
                  where "EMPLOYEE_ID" = '205' and   "EMPLOYEE_ID","FIRST_NAME",
                  "FIRST_NAME" = 'Shelley' and      "LAST_NAME","EMAIL","PHONE_NUMBER",
                  "LAST_NAME" = 'Higgins' and       "HIRE_DATE", "JOB_ID","SALARY",
                  "EMAIL" = 'SHIGGINS' and          "COMMISSION_PCT","MANAGER_ID",
                  "PHONE_NUMBER" = '515.123.8080'   "DEPARTMENT_ID") values
                  and "HIRE_DATE" = TO_DATE(        ('205','Shelley','Higgins',
                  '07-jun-1994 10:05:01',           and     'SHIGGINS','515.123.8080',
                  'dd-mon-yyyy hh24:mi:ss')         TO_DATE('07-jun-1994 10:05:01',
                  and "JOB_ID" = 'AC_MGR'           'dd-mon-yyyy hh24:mi:ss'),
                  and "SALARY"= '12000'            'AC_MGR','12000',NULL,'101','110'); 
                  and "COMMISSION_PCT" IS NULL 
                  and "MANAGER_ID" 
                  = '101' and "DEPARTMENT_ID" = 
                  '110' and ROWID = 
                  'AAAHSkAABAAAY6rAAM';
OE     1.8.1484   set transaction read write;
OE     1.8.1484   update "OE"."PRODUCT_INFORMATION"  update "OE"."PRODUCT_INFORMATION"
                  set "WARRANTY_PERIOD" =            set "WARRANTY_PERIOD" = 
                  TO_YMINTERVAL('+12-06') where      TO_YMINTERVAL('+20-00') where
                  "PRODUCT_ID" = '2350' and          "PRODUCT_ID" = '2350' and
                  "WARRANTY_PERIOD" =                "WARRANTY_PERIOD" =
                  TO_YMINTERVAL('+20-00') and        TO_YMINTERVAL('+20-00') and
                  ROWID = 'AAAHTKAABAAAY9tAAD';       ROWID ='AAAHTKAABAAAY9tAAD'; 
HR     1.11.1476  commit;

Step 4 End the LogMiner session.

SQL> EXECUTE DBMS_LOGMNR.END_LOGMNR();

Mining Without Specifying the List of Redo Log Files Explicitly

The previous example explicitly specified the redo log file or files to be mined. However, if you are mining in the same database that generated the redo log files, then you can mine the appropriate list of redo log files by just specifying the time (or SCN) range of interest. To mine a set of redo log files without explicitly specifying them, use the DBMS_LOGMNR.CONTINUOUS_MINE option to the DBMS_LOGMNR.START_LOGMNR procedure, and specify either a time range or an SCN range of interest.

Example : Mining Redo Log Files in a Given Time Range

This example assumes that you want to use the data dictionary extracted to the redo log files.

Step 1 Determine the timestamp of the redo log file that contains the start of the data dictionary.

SQL> SELECT NAME, FIRST_TIME FROM V$ARCHIVED_LOG
WHERE SEQUENCE# = (SELECT MAX(SEQUENCE#) FROM V$ARCHIVED_LOG 
       WHERE DICTIONARY_BEGIN = 'YES');
NAME                                          FIRST_TIME
--------------------------------------------  --------------------
/usr/oracle/data/db1arch_1_207_482701534.dbf  10-jan-2003 12:01:34

Step 2 Display all the redo log files that have been generated so far.

This step is not required, but is included to demonstrate that the CONTINUOUS_MINE option works as expected, as will be shown in Step 4.

SQL> SELECT FILENAME name FROM V$LOGMNR_LOGS
       WHERE LOW_TIME > '10-jan-2003 12:01:34';
NAME
----------------------------------------------
/usr/oracle/data/db1arch_1_207_482701534.dbf
/usr/oracle/data/db1arch_1_208_482701534.dbf
/usr/oracle/data/db1arch_1_209_482701534.dbf
/usr/oracle/data/db1arch_1_210_482701534.dbf

Step 3 Start LogMiner.

Start LogMiner by specifying the dictionary to use and the COMMITTED_DATA_ONLY, PRINT_PRETTY_SQL, and CONTINUOUS_MINE options.

SQL> EXECUTE DBMS_LOGMNR.START_LOGMNR(-
       STARTTIME => '10-jan-2003 12:01:34', -
         ENDTIME => SYSDATE, -
                OPTIONS => DBMS_LOGMNR.DICT_FROM_REDO_LOGS + -
                    DBMS_LOGMNR.COMMITTED_DATA_ONLY + -
                    DBMS_LOGMNR.PRINT_PRETTY_SQL + -
                    DBMS_LOGMNR.CONTINUOUS_MINE);

Step 4 Query the V$LOGMNR_LOGS view.

This step shows that the DBMS_LOGMNR.START_LOGMNR procedure with the CONTINUOUS_MINE option includes all of the redo log files that have been generated so far, as expected. (Compare the output in this step to the output in Step 2.)

SQL> SELECT FILENAME name FROM V$LOGMNR_LOGS; 
NAME
------------------------------------------------------
/usr/oracle/data/db1arch_1_207_482701534.dbf
/usr/oracle/data/db1arch_1_208_482701534.dbf
/usr/oracle/data/db1arch_1_209_482701534.dbf
/usr/oracle/data/db1arch_1_210_482701534.dbf

Step 5 Query the V$LOGMNR_CONTENTS view.

To reduce the number of rows returned by the query, exclude all DML statements done in the sys or system schema. (This query specifies a timestamp to exclude transactions that were involved in the dictionary extraction.)

Note that all reconstructed SQL statements returned by the query are correctly translated.

SQL> SELECT USERNAME AS usr,(XIDUSN || '.' || XIDSLT || '.' || XIDSQN) as XID,
       SQL_REDO FROM V$LOGMNR_CONTENTS 
       WHERE SEG_OWNER IS NULL OR SEG_OWNER NOT IN ('SYS', 'SYSTEM') AND
       TIMESTAMP > '10-jan-2003 15:59:53';
USR             XID         SQL_REDO
-----------     --------    -----------------------------------
SYS             1.2.1594    set transaction read write;
SYS             1.2.1594    create table oe.product_tracking (product_id number not null,
                            modified_time date,
                            old_list_price number(8,2),
                            old_warranty_period interval year(2) to month);
SYS             1.2.1594    commit;
SYS             1.18.1602   set transaction read write;
SYS             1.18.1602   create or replace trigger oe.product_tracking_trigger
                            before update on oe.product_information
                            for each row
                            when (new.list_price <> old.list_price or
                                  new.warranty_period <> old.warranty_period)
                            declare
                            begin
                            insert into oe.product_tracking values 
                               (:old.product_id, sysdate,
                                :old.list_price, :old.warranty_period);
                            end;
SYS             1.18.1602   commit;
OE              1.9.1598    update "OE"."PRODUCT_INFORMATION"
                              set
                                "WARRANTY_PERIOD" = TO_YMINTERVAL('+08-00'),
                              "LIST_PRICE" = 100
                              where
                                "PRODUCT_ID" = 1729 and
                                "WARRANTY_PERIOD" = TO_YMINTERVAL('+05-00') and
                                "LIST_PRICE" = 80 and
                                ROWID = 'AAAHTKAABAAAY9yAAA';
OE              1.9.1598    insert into "OE"."PRODUCT_TRACKING"
                              values
                                "PRODUCT_ID" = 1729,
                                "MODIFIED_TIME" = TO_DATE('13-jan-2003 16:07:03',
				"OLD_LIST_PRICE" = 80,
                                "OLD_WARRANTY_PERIOD" = TO_YMINTERVAL('+05-00');
OE              1.9.1598    update "OE"."PRODUCT_INFORMATION"
                              set
                                "WARRANTY_PERIOD" = TO_YMINTERVAL('+08-00'),
	                        "LIST_PRICE" = 92
                              where
                                "PRODUCT_ID" = 2340 and
                                "WARRANTY_PERIOD" = TO_YMINTERVAL('+05-00') and
                            "LIST_PRICE" = 72 and
                                ROWID = 'AAAHTKAABAAAY9zAAA';
OE              1.9.1598    insert into "OE"."PRODUCT_TRACKING"
                              values
                                "PRODUCT_ID" = 2340,
                                "MODIFIED_TIME" = TO_DATE('13-jan-2003 16:07:07',
                         'dd-mon-yyyy hh24:mi:ss'),
                                "OLD_LIST_PRICE" = 72,
                                "OLD_WARRANTY_PERIOD" = TO_YMINTERVAL('+05-00');
OE              1.9.1598     commit;

Step 6 End the LogMiner session.

SQL> EXECUTE DBMS_LOGMNR.END_LOGMNR();

 

 

 


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