When you use the SKIP_CORRUPTION option to DBMS_LOGMNR.START_LOGMNR, any corruptions in the redo log files are skipped during select operations from the V$LOGMNR_CONTENTS view. For every corrupt redo record encountered, a row is returned that contains the value CORRUPTED_BLOCKS in the OPERATION column, 1343 in the STATUS column, and the number of blocks skipped in the INFO column.
Be aware that the skipped records may include changes to ongoing transactions in the corrupted blocks; such changes will not be reflected in the data returned from the V$LOGMNR_CONTENTS view.
The default is for the select operation to terminate at the first corruption it encounters in the redo log file.
The following SQL example shows how this option works:
-- Add redo log files of interest. -- EXECUTE DBMS_LOGMNR.ADD_LOGFILE(- logfilename => '/usr/oracle/data/db1arch_1_16_482701534.log' - options => DBMS_LOGMNR.NEW); -- Start LogMiner -- EXECUTE DBMS_LOGMNR.START_LOGMNR(); -- Select from the V$LOGMNR_CONTENTS view. This example shows corruptions are -- in the redo log files. -- SELECT rbasqn, rbablk, rbabyte, operation, status, info FROM V$LOGMNR_CONTENTS; ERROR at line 3: ORA-00368: checksum error in redo log block ORA-00353: log corruption near block 6 change 73528 time 11/06/2011 11:30:23 ORA-00334: archived log: /usr/oracle/data/dbarch1_16_482701534.log -- Restart LogMiner. This time, specify the SKIP_CORRUPTION option. -- EXECUTE DBMS_LOGMNR.START_LOGMNR(- options => DBMS_LOGMNR.SKIP_CORRUPTION); -- Select from the V$LOGMNR_CONTENTS view again. The output indicates that -- corrupted blocks were skipped: CORRUPTED_BLOCKS is in the OPERATION -- column, 1343 is in the STATUS column, and the number of corrupt blocks -- skipped is in the INFO column. -- SELECT rbasqn, rbablk, rbabyte, operation, status, info FROM V$LOGMNR_CONTENTS; RBASQN RBABLK RBABYTE OPERATION STATUS INFO 13 2 76 START 0 13 2 76 DELETE 0 13 3 100 INTERNAL 0 13 3 380 DELETE 0 13 0 0 CORRUPTED_BLOCKS 1343 corrupt blocks 4 to 19 skipped 13 20 116 UPDATE 0