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Thanks for the reply .. It gives me the segment name ...
SQL> select segment_name from dba_extents where file_id = 3
2 and 47460 between block_id and block_id + blocks -1
How can i dump this segment ? And if i want to dump only that particular UNDO entry , can i do it ?
I want to study the working of UNDO and REDO .. And so wanted to study them block by block.
Thanks a lot for your help ..
Just one last question ,
alter system dump undo header '_SYSSMU5_1192467665$';
dumps only segment header of the segment and not the entries ?
Your command to dump particular block entry works completely fine .. Thanks for that ..
If you need to dump an undo block use this syntax:
ALTER SYSTEM DUMP undo block RBS_NAME xid XIDUSN, XIDSLOT, XIDSQN;
For interpretation the trace file, I will read below thread:
alter system dump undo header interpretation And answer by Robert sir.
Related links are:
Please give plenty of time to read the above link, because you are reading UNDO; oracle's one of the most important, complex and interesting topic.
I mentioned ALTER SYSTEM DUMP undo block RBS_NAME xid XIDUSN, XIDSLOT, XIDSQN;
means you are going to dump directly of undo datafile and said block, you are saying alter system dump undo block (i am going to dump undo block); while;
If you says : allter system dump datafile <number datafile> block <<block number>>; means you are going to dump any datafile's block with datafile number and block. So, the difference is ...dump undo block and ...dump datafile. As far as technical differences, i have'nt gone till now to see the exact difference, but i think there will no change in the trace file as such, because at last you wish to see the dump of block.
Dumping of undo is divided into following topics:
(A) Undo Header
(B) Undo Segment
(B) Undo Block
I am sorry if it sounds like a stupid question ... But i am new to this area ...
Just one thing , UNDO tablespace also finally resides in the datafiles right ?
And when i give the file number of undotablespace file in alter system dump datafile << file number >> ,
it will dump undo file contents , isn't it ?
Atleast that gave me the undo contents as output , when i tried !!
Something like this :-
* Rec #0x1 slt: 0x20 objn: 5965(0x0000174d) objd: 5965 tblspc: 1(0x00000001)
* Layer: 10 (Index) opc: 21 rci 0x00
Undo type: Regular undo Last buffer split: No
Temp Object: No
Tablespace Undo: No
index general undo (branch) operations
op: 0x05 ver: 0x01
compat bit: 4 (post-11) padding: 0
op: R itc: 2
Itl Xid Uba Flag Lck Scn/Fsc
0x01 0x0005.005.00001a42 0x00c0b963.07ba.01 C--- 0 scn 0x0000.0089a0fc
0x02 0x0007.006.00001a23 0x00c08ab1.0675.27 C--- 0 scn 0x0000.0089831c
Dump kdige : block dba :0x00814976, seghdr dba: 0x00801003
make leaf block empty
(2): 01 00