A shallow summary of oracle log miner

Sometimes, we should recover one or more rows data which is deleted carelessly by users, but it is not necessary to recover the whole db and the flashback does not recovery the data because it's timeout.

For this moment, we should mine the log file to find the redo or undo data to recover the loss data and  find who delete the data.

How to use the log miner?

After oracle 9i, oracle provides a tool to mine the log file, there is a package of oracle dbms for the logmnr named dbms_logmnr. 

Make sure the db is archive log mode

SQL> archive log list
Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            +FAR/arch1
Oldest online log sequence     833
Next log sequence to archive   834
Current log sequence           834
SQL>

Example of log miner analyze procedure:
SQL>
SQL> create table test(id number);

Table created.

SQL> insert into test values(1);

1 row created.

SQL> /

1 row created.

SQL> /

1 row created.

SQL> commit;

Commit complete.

SQL> begin
  2  for i in 1..100 loop
  3  insert into test values(i);
  4  commit;
  5  end loop;
  6  end;
  7  /

PL/SQL procedure successfully completed.

Switch log file  by user system

SQL> alter system switch logfile;

System altered.

SQL>

Engine the log miner.

select name, thread#, sequence#, first_change#, next_change# from V$ARCHIVED_LOG;
NAME                    THREAD#  SEQUENCE# FIRST_CHANGE# NEXT_CHANGE#
-------------------- ---------- ---------- ------------- ------------
                              1        831    4062556971   4064186822
                              2        634    4063922165   4064177226
                              2        635    4064177226   4064275220
                              2        636    4064275220   4064429426
                              1        832    4064186822   4066775319
+FAR/arch1/1_833_817          1        833    4066775319   4066914873
620325.dbf

+FAR/arch1/1_834_817          1        834    4066914873   4071821640
620325.dbf

NAME                    THREAD#  SEQUENCE# FIRST_CHANGE# NEXT_CHANGE#
-------------------- ---------- ---------- ------------- ------------
+FAR/arch2/2_637_817          2        637    4064429426   4071821645
620325.dbf

SQL> exec dbms_logmnr.add_logfile(logfilename=>'+FAR/arch1/1_834_817620325.dbf', options=>dbms_logmnr.new);

PL/SQL procedure successfully completed.

SQL>

options: dbms_logmnr.new   stand for  the first log file to be analyzed.

SQL> exec dbms_logmnr.start_logmnr(options => sys.dbms_logmnr.dict_from_online_catalog);

PL/SQL procedure successfully completed.

SQL>

select scn, timestamp, seg_name, seg_owner, sql_redo, sql_undo from v$logmnr_contents where seg_name='TEST' and set_owner='RAY';

     SCN TIMESTAMP SEG_NAME   SEG_OWNER  SQL_REDO                                 SQL_UNDO
---------- --------- ---------- ---------- ---------------------------------------- ----------------------------------------
4071818078 11-SEP-13 TEST       RAY        create table test(id number);
4071818819 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '1
                                           1');                                     ' and ROWID = 'AAAY8eAAFAAABbNAAA';

4071818840 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '1
                                           1');                                     ' and ROWID = 'AAAY8eAAFAAABbNAAB';

4071818851 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '1
                                           1');                                     ' and ROWID = 'AAAY8eAAFAAABbNAAC';

4071819125 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '1

       SCN TIMESTAMP SEG_NAME   SEG_OWNER  SQL_REDO                                 SQL_UNDO
---------- --------- ---------- ---------- ---------------------------------------- ----------------------------------------
                                           1');                                     ' and ROWID = 'AAAY8eAAFAAABbNAAD';

4071819127 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '2
                                           2');                                     ' and ROWID = 'AAAY8eAAFAAABbNAAE';

4071819129 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '3
                                           3');                                     ' and ROWID = 'AAAY8eAAFAAABbNAAF';

4071819131 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '4
                                           4');                                     ' and ROWID = 'AAAY8eAAFAAABbNAAG';

...............

       SCN TIMESTAMP SEG_NAME   SEG_OWNER  SQL_REDO                                 SQL_UNDO
---------- --------- ---------- ---------- ---------------------------------------- ----------------------------------------

4071819228 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '5
                                           53');                                    3' and ROWID = 'AAAY8eAAFAAABbNAA3';

4071819231 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '5
                                           54');                                    4' and ROWID = 'AAAY8eAAFAAABbNAA4';

4071819233 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '5
                                           55');                                    5' and ROWID = 'AAAY8eAAFAAABbNAA5';

4071819235 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '5

       SCN TIMESTAMP SEG_NAME   SEG_OWNER  SQL_REDO                                 SQL_UNDO
---------- --------- ---------- ---------- ---------------------------------------- ----------------------------------------
                                           56');                                    6' and ROWID = 'AAAY8eAAFAAABbNAA6';

4071819237 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '5
                                           57');                                    7' and ROWID = 'AAAY8eAAFAAABbNAA7';

4071819239 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '5
                                           58');                                    8' and ROWID = 'AAAY8eAAFAAABbNAA8';

4071819241 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '5
                                           59');                                    9' and ROWID = 'AAAY8eAAFAAABbNAA9';

       SCN TIMESTAMP SEG_NAME   SEG_OWNER  SQL_REDO                                 SQL_UNDO
---------- --------- ---------- ---------- ---------------------------------------- ----------------------------------------
4071819243 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '6
                                           60');                                    0' and ROWID = 'AAAY8eAAFAAABbNAA+';

4071819244 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '6
                                           61');                                    1' and ROWID = 'AAAY8eAAFAAABbNAA/';

4071819247 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '6
                                           62');                                    2' and ROWID = 'AAAY8eAAFAAABbNABA';

4071819249 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '6
                                           63');                                    3' and ROWID = 'AAAY8eAAFAAABbNABB';

...........
       SCN TIMESTAMP SEG_NAME   SEG_OWNER  SQL_REDO                                 SQL_UNDO
---------- --------- ---------- ---------- ---------------------------------------- ----------------------------------------
                                           78');                                    8' and ROWID = 'AAAY8eAAFAAABbNABQ';

4071819285 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '7
                                           79');                                    9' and ROWID = 'AAAY8eAAFAAABbNABR';

4071819288 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '8
                                           80');                                    0' and ROWID = 'AAAY8eAAFAAABbNABS';

4071819290 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '8
                                           81');                                    1' and ROWID = 'AAAY8eAAFAAABbNABT';

       SCN TIMESTAMP SEG_NAME   SEG_OWNER  SQL_REDO                                 SQL_UNDO
---------- --------- ---------- ---------- ---------------------------------------- ----------------------------------------
4071819292 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '8
                                           82');                                    2' and ROWID = 'AAAY8eAAFAAABbNABU';

4071819294 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '8
                                           83');                                    3' and ROWID = 'AAAY8eAAFAAABbNABV';

4071819296 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '8
                                           84');                                    4' and ROWID = 'AAAY8eAAFAAABbNABW';

4071819298 11-SEP-13 TEST       RAY        insert into "RAY"."TEST"("ID") values (' delete from "RAY"."TEST" where "ID" = '8
                                           85');                                    5' and ROWID = 'AAAY8eAAFAAABbNABX';

SQL> exec dbms_logmnr.end_logmnr;

PL/SQL procedure successfully completed.

For oracle log miner, we should pay attention to another main points.