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March 21, 2009

Force RMAN to ignore corrupted blocks with COPY command

Filed under: Oracle How To — H.Tonguç Yılmaz @ 2:40 pm

To tell RMAN to permit corrupt blocks to be backed up you must use the SET MAXCORRUPT command(note that this goes inside the RUN command);

SET MAXCORRUPT FOR DATAFILE ‘foo’ TO n;

where ‘n’ is the number of corrupt blocks which will be allowed in the backup. However the ‘set maxcorrupt’ command only applies to the rman BACKUP command not the rman COPY command. To work around this problem for the rman COPY command you must modify “recover.bsq”.

Find the line in “$ORACLE_HOME/rdbms/admin/recover.bsq” which looks like this:

sys.dbms_backup_restore.copyDataFile(full_name =full_name,

and add the following line immediately after that line:

max_corrupt =1,

For more information please see metalink note 1069093.6.

Hot discussion: SQL or PL/SQL

Filed under: Oracle Performance — H.Tonguç Yılmaz @ 9:50 am

I read Rob, Laurent and Chen on this topic. As far as I follow OTN SQL and PL/SQL forum is the place for SQL madness, any kind of question here is discussed in a race to have a more performant single SQL solution. Oracle provides very rich SQL options like analytic, xml and data mining functions or model clause for this kind of a race.

Additionally we know by experience that any data intensive need will have several different solutions and *usually* one set based SQL solutions will be faster than its alternatives especially row based(cursor looping) PL/SQL ones. So parallel to the need there can be exceptions, you may check Nicolas Gasparotto‘s approach on this example with pipelined PL/SQL function option.

IMHO if you are not solving a puzzle but developing an application in a team, PL/SQL based solutions are easier to understand for all team members and as a result it is easier to maintain the application in long run. After all performance is not the single metric for an application’s success, PL/SQL provides exception handling and is also rich with bulk processing and pipelined functions kind of options for related performance needs.

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