SQL> update t set owner='killdb.com' where object_id=555;

已更新 1 行。

SQL> select xidusn,xidslot,xidsqn,ubablk,ubafil,ubarec,START_SCN from v$transaction;

    XIDUSN    XIDSLOT     XIDSQN     UBABLK     UBAFIL     UBAREC  START_SCN
---------- ---------- ---------- ---------- ---------- ---------- ----------
         6         15        916        366          3          6     968248

SQL>  select  dbms_rowid.rowid_block_number(rowid) blk# from t  where object_id=555;

      BLK#
----------
       491


SQL> select distinct dbms_rowid.rowid_relative_fno(rowid) file# from t;

     FILE#
----------
         5

alter system dump datafile 5 block 491;

Block header dump:  0x014001eb
 Object id on Block? Y
 seg/obj: 0x15a1d  csc: 0x00.ef4ce  itc: 3  flg: E  typ: 1 - DATA
     brn: 0  bdba: 0x14001e8 ver: 0x01 opc: 0
     inc: 0  exflg: 0

 Itl           Xid                  Uba         Flag  Lck        Scn/Fsc
0x01   0xffff.000.00000000  0x00000000.0000.00  C---    0  scn 0x0000.000ec619
0x02   0x0006.00f.00000394  0x00c0016e.0085.06  ----    1  fsc 0x0000.00000000
0x03   0x0000.000.00000000  0x00000000.0000.00  ----    0  fsc 0x0000.00000000
bdba: 0x014001eb
data_block_dump,data header at 0xfffffd7ffdd34a7c
===============
tsiz: 0x1f80
hsiz: 0x474
pbl: 0xfffffd7ffdd34a7c
     76543210
flag=--------
ntab=1
nrow=561
frre=-1
fsbo=0x474
fseo=0x799
avsp=0x330
tosp=0x330
0xe:pti[0]      nrow=561        offs=0
0x12:pri[0]     offs=0x1f76
0x14:pri[1]     offs=0x1f6c
0x16:pri[2]     offs=0x1f62
0x18:pri[3]     offs=0x1f58
0x1a:pri[4]     offs=0x1f4e
0x1c:pri[5]     offs=0x1f44
0x1e:pri[6]     offs=0x1f3a
0x20:pri[7]     offs=0x1f30
0x22:pri[8]     offs=0x1f26
0x24:pri[9]     offs=0x1f1c
0x26:pri[10]    offs=0x1f12
0x28:pri[11]    offs=0x1f08


0x02   0x0006.00f.00000394  0x00c0016e.0085.06  ----    1  fsc 0x0000.00000000


SQL>  select dbms_utility.data_block_address_file(to_number(substr(uba, 3, 8),
                                                          'xxxxxxxxxxxx')) as undo_file#,
           dbms_utility.data_block_address_block(to_number(substr(uba, 3, 8),
                                                           'xxxxxxxxxxxx')) as undo_block,
           to_number(substr(uba, 12, 4), 'xxxxxxxxxxxx') undo_sequence,
           to_number(substr(uba, 17, 2), 'xxxxxxxxxxxx') undo_record
      from (select '0x00c0016e.0085.06' uba from dual);  2    3    4    5    6    7  

UNDO_FILE# UNDO_BLOCK UNDO_SEQUENCE UNDO_RECORD
---------- ---------- ------------- -----------
         3        366           133           6


uba = Address of the last undo block used + Sequence + Last Entry in UNDO record map


dump undo header:
SQL>  select name from v$rollname where usn=6;

NAME
------------------------------
_SYSSMU6_112126372$

alter system dump undo header '_SYSSMU6_112126372$';


********************************************************************************
Undo Segment:  _SYSSMU6_112126372$ (6)
********************************************************************************
  Extent Control Header
  -----------------------------------------------------------------
  Extent Header:: spare1: 0      spare2: 0      #extents: 4      #blocks: 151
                  last map  0x00000000  #maps: 0      offset: 4080
      Highwater::  0x00c0016f  ext#: 2      blk#: 7      ext size: 8
  #blocks in seg. hdr's freelists: 0
  #blocks below: 0
  mapblk  0x00000000  offset: 2
                   Unlocked
     Map Header:: next  0x00000000  #extents: 4    obj#: 0      flag: 0x40000000
  Extent Map
  -----------------------------------------------------------------
   0x00c000d1  length: 7
   0x00c000d8  length: 8
   0x00c00168  length: 8
   0x00c00900  length: 128

 Retention Table
  -----------------------------------------------------------
 Extent Number:0  Commit Time: 1408809628
 Extent Number:1  Commit Time: 1408809628
 Extent Number:2  Commit Time: 1408846934
 Extent Number:3  Commit Time: 1408809628

  TRN CTL:: seq: 0x0085 chd: 0x000b ctl: 0x0012 inc: 0x00000000 nfb: 0x0001
            mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
            uba: 0x00c0016f.0085.01 scn: 0x0000.000ebd47
Version: 0x01
  FREE BLOCK POOL::
    uba: 0x00c0016f.0085.01 ext: 0x2  spc: 0x1f84
    uba: 0x00000000.0085.02 ext: 0x2  spc: 0x1ee2
    uba: 0x00000000.0085.1f ext: 0x2  spc: 0x978
    uba: 0x00000000.0000.00 ext: 0x0  spc: 0x0
    uba: 0x00000000.0000.00 ext: 0x0  spc: 0x0
  TRN TBL::

  index  state cflags  wrap#    uel         scn            dba            parent-xid    nub     stmt_num    cmt
  ------------------------------------------------------------------------------------------------
   0x0a    9    0x00  0x0394  0x0012  0x0000.000ec5eb  0x00c0016d  0x0000.000.00000000  0x00000001   0x00000000  1408814848
   0x0b    9    0x00  0x0393  0x0015  0x0000.000ebd59  0x00c0016c  0x0000.000.00000000  0x00000001   0x00000000  1408810230
   0x0c    9    0x00  0x0394  0x0006  0x0000.000ec5e8  0x00c0016e  0x0000.000.00000000  0x00000001   0x00000000  1408814848
   0x0d    9    0x00  0x0393  0x0019  0x0000.000ec24e  0x00c0016c  0x0000.000.00000000  0x00000001   0x00000000  1408813250
   0x0e    9    0x00  0x0394  0x000c  0x0000.000ec5ae  0x00c0016d  0x0000.000.00000000  0x00000001   0x00000000  1408814750
   0x0f   10    0x80  0x0394  0x0002  0x0000.000ec638  0x00c0016e  0x0000.000.00000000  0x00000001   0x00000000  0

  usn: 6
  sp1:0x00000000 sp2:0x00000000 sp3:0x00000000 sp4:0x00000000
  sp5:0x00000000 sp6:0x00000000 sp7:0x00000000 sp8:0x00000000
  EXT TRN TBL::


这里的dba=0x00c0016e和uba=0x00c0016e.0085.06 一致。