Reset OC4J Admin Password

Reset the oc4jadmin password using the following procedure while you are logged in as the user who installed the Oracle Application Server instance:

1. Stop OC4J and the Application Server Control.

   Enter the following command in the Oracle home of the application server instance:

   (UNIX) ORACLE_HOME/opmn/bin/opmnctl stopproc ias-component=OC4J
   (Windows) ORACLE_HOME\opmn\bin\opmnctl stopproc ias-component=OC4J
   
   

2. Locate and open the following file in a text editor:

   (UNIX)ORACLE_HOME/j2ee/home/config/system-jazn-data.xml
   (Windows)ORACLE_HOME\j2ee\home\config\system-jazn-data.xml
   
   

3. Locate the line that defines the credentials property for the oc4jadmin user.

   The following example shows the section of system-jazn-data.xml with the encrypted credentials entry in boldface type:

   
   
      jazn.com
      
       .
       .
             oc4jadmin
            OC4J Administrator
            OC4J Administrator
               {903}4L50lHJWIFGwLgHXTub7eYK9e0AnWLUH
         
   

4. Replace the existing encrypted password with the new password.

   Be sure to prefix the password with an exclamation point (!). For example:

   !mynewpassword123

ORA-27047: unable to read the header block of file

If while restoring backup, Db errors out with ORA-27047, it implied that the block header is corrupt.

Following three actions can be taken to restore DB:

1. resize the database file in the source system and again take the cold backup. Resizing reformats the block header.
2. use the existing control files to startup the database and then resize the file.
3. If control files can not be reused, because of the change in file location where db files will be restored, just take the cold backup copy of only the resized file from the source system. replace the existing corrupt header file with the newly backup copy and create the control file.
revert back to the original corrupt header file and try to open db with the newly created control file. It will fail with checkpoint mismatch asking for some file needing recovery.
Give the command "recover database using backup control file". When asked for the achive logs, supply the redo log file (try with each of the log files), it will recover the DB.

Oracle BITMAP Index Structure

Index block with PCTFREE 50

select extent_id, file_id,block_id from dba_extents where segment_name='IND_BMP_50' order by extent_id

EXTENT_ID FILE_ID BLOCK_ID
---------- ---------- ----------
0 1074 53953
1 1115 53841
2 1196 53745
3 1742 447857
4 1744 446833


SQL > alter system dump datafile 1742 block 447857

row#0[6126] flag: ------, lock: 0, len=1906
col 0; len 1; (1): 80 <-key value
col 1; len 6; (6): 2b 40 d2 29 00 08 <-Starting Rowid
col 2; len 6; (6): 2b 40 d2 c1 00 1f <-Ending Rowid
col 3; len 1886; (1886): <-Bitmap for the key value


row#1[4221] flag: ------, lock: 0, len=1905
col 0; len 1; (1): 80
col 1; len 6; (6): 2b 40 d2 c1 00 30
col 2; len 6; (6): 2b 40 d3 48 00 67
col 3; len 1885; (1885):

There are two rows in the block. Totallying their column size :
1+6+6+1886+1+6+6+1885 = 3797kb
So, block is occupying approx 50% of the block (8192kb)



Index block with PCTFREE 10

SQL> select extent_id, file_id,block_id from dba_extents where segment_name='IND_BMP_10' order by extent_id;

EXTENT_ID FILE_ID BLOCK_ID
---------- ---------- ----------
0 1074 63057
1 1115 62945
2 1196 62849
3 1742 457377
4 1744 456177
5 1786 429665
6 1809 411889


alter system dump datafile 1742 block 457377

row#0[4495] flag: ------, lock: 0, len=3537
col 0; len 1; (1): 80 <-key value
col 1; len 6; (6): b3 c6 f6 2b 00 28 <-Starting rowid
col 2; len 6; (6): b3 c6 f6 ce 00 37 <-Ending rowid
col 3; len 3517; (3517): <-Bitmap for the key value


row#1[957] flag: ------, lock: 0, len=3538
col 0; len 1; (1): 80
col 1; len 6; (6): b3 c6 f6 ce 00 48
col 2; len 6; (6): b3 c6 f7 74 00 37
col 3; len 3518; (3518):


There are two rows in the block. Totallying their column size:
1+6+6+3517+1+6+6+3518 = 7161 kb
So, block is occupying approx 90% of the block (8192kb)