SCN in the block ?

[Sonia]

Hi,
Is SCN no also stamped in the header of
the oracle data block., if so is there any way
of seeing it.
Regards
sonia

[SANJAY_G]

Yes. the block header contains SCN no. for the block. I am not sure but I think dumping the block may show the SCN.

Sanjay

[SANJAY_G]

You can see the SCN by dumping the block.
e.g.

Oracle process number: 11
Unix process pid: 4227, image: oraclefdbsd

*** 2002-09-16 14:29:01.920
*** SESSION ID:(8.868) 2002-09-16 14:29:01.919
Start dump data blocks tsn: 4 file#: 5 minblk 1312 maxblk 1312
buffer tsn: 4 rdba: 0x01400520 (5/1312)
scn:0x0000.00193717 seq:0x03 flg:0x00 tail:0x37171003
       frmt:0x02 chkval:0x0000 type:0x10=DATA SEGMENT HEADER - UNLIMITED
 
  Extent Control Header
  -----------------------------------------------------------------
  Extent Header:: spare1: 0      tsn: 4      #extents: 11     #blocks: 1549  
                  last map rdba: 0x00000000  #maps: 0      offset: 4128  
      Highwater:: rdba: 0x014020ca  ext#: 10     blk#: 97     ext size: 520

00193717 is the HEX value, convert it to decimal which is the SCN for the block.

Sanjay

[Sonia]

thanx sanjay,
Can u pls tell me who is responsible for updating the scn in the block and when it will be updated ? duing a checkpoint ?
Regards
sonia

[Sonia]

thanx sanjay,
Can u pls tell me who is responsible for updating the scn in the block and when it will be updated ? duing a checkpoint ?
Regards
sonia

[SANJAY_G]

Whenever a transaction is commited a new SCN is issued I am not sure which process will right SCN to the data block.

Sanjay

[Sonia]

Hi sanjay,
U had told about dumping the block....
How exactly to do that...
regards
sonia

[SANJAY_G]

From SVRMGR do this..

ALTER SYSTEM DUMP DATAFILE FILE# BLOCK BLOCK#;

One trace file will be generated in the UDUMP directory.

Sanjay

[sm8728]

I don't think there is anything like block scn scn is for datafile and on dumping the block u see the file scn only am i correct sonia/sanjay

[quester]

In my little knowledge, I know that SCNs are for Data File Headers, Control Files, Redo Logs and Rollback Segments. They are NOT for data blocks. CKPT archive process writes the SCNs to these files when a COMMIT is initiated.