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undo transaction slot被覆盖引起ORA-01555的原理解析

原创 Oracle 作者:oliseh 时间:2014-09-14 10:48:31 1 删除 编辑

测试环境:oracle 11gR2 Restart

测试目的:模拟undo header事务表槽被覆盖引起ORA-01555的现象及原理解析

场景介绍:

Session 1

获取scott.tabnow1表中记录对应的relative_fnoblock_number

Update一条记录,但不commit,记录下所使用的xiduba信息

Session 2

以非SYS用户连接执行:set transaction read only;

Session 1

Commit;

Session 3

scott.t1表连续做update+commit操作

Session 2

成功遍历scott.tabnow1

select * from scott.tabnow1;

Session 4

再次对scott.t1表连续做update+commit操作,继续覆盖事务表

Session 2

再次遍历scott.tabnow1

得到ORA-01555错误

测试数据库配置:

##为简化测试过程,建立了一个256Kundotbs

SQL> show parameter undo

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

undo_management                      string      AUTO

undo_retention                       integer     900

undo_tablespace                      string      UNDOSIG

SQL> select d.name,d.bytes from v$datafile d,v$tablespace t where t.ts#=d.ts# and t.name='UNDOSIG';

NAME                                          BYTES

---------------------------------------- ----------

+STESTDG1/stest2/undosig.dbf                 262144

##undosig里只有一个undo segment online

SQL> select segment_name,tablespace_name,relative_fno,status from dba_rollback_segs where tablespace_name='UNDOSIG';

SEGMENT_NAME                   TABLESPACE_NAME                RELATIVE_FNO STATUS

------------------------------ ------------------------------ ------------ ----------------

_SYSSMU2$                      UNDOSIG                                   8 ONLINE

##undo segmentextent的分布情况,除去undo header所占据的block 8block 9~31都可以被事务用来存放修改前内容:

SQL> select segment_name,extent_id,file_id,block_id,blocks from dba_extents where segment_name='_SYSSMU2$';

SEGMENT_NAME                    EXTENT_ID    FILE_ID   BLOCK_ID     BLOCKS

------------------------------ ---------- ---------- ---------- ----------

_SYSSMU2$                               0          8          8          8

_SYSSMU2$                               1          8         16          8

_SYSSMU2$                               2          8         24          8

##测试用到的两张表初始内容:

SQL> select * from scott.tabnow1;

USERNAME                          USER_ID CREATED

------------------------------ ---------- ------------

XS$NULLLL                        2147483638 21-OCT-11

NEWUSER                                84 12-MAR-14

SCOTTTTT                               83 21-OCT-11

OWBSYS_AUDIT                           82 21-OCT-11

OWBSYS                                 78 21-OCT-11

APEX                                   77 21-OCT-11

APEX_PUBLIC                            75 21-OCT-11

FLOWS_FILE                             74 21-OCT-11

MGMT_VIEW                              73 21-OCT-11

DDD                                    34 28-MAY-14

SQL> select * from scott.t1;

        ID

----------

        34

        34

开始测试过程:

/////////////

//session 1:

/////////////

##确定scott.tabnow1表中的记录所在的块,便于之后对data blockdump;所有的行都在同一个block

select dbms_rowid.rowid_relative_fno(rowid) rfno,dbms_rowid.rowid_block_number(rowid) blkno from scott.tabnow1;

       RFNO      BLKNO

---------- ----------

         4       1779

         4       1779

         4       1779

         4       1779

         4       1779

         4       1779

         4       1779

         4       1779

         4       1779

         4       1779

##记录一下undo header的初始状态,slot 0x1e将成为下一个要用到的slot

  TRN CTL:: seq: 0x187e chd: 0x001e ctl: 0x0000 inc: 0x00000000 nfb: 0x0001

            mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)

            uba: 0x02000010.187e.18 scn: 0x0000.00ae9095

  TRN TBL::

  index  state cflags  wrap#    uel         scn            dba            parent-xid    nub     stmt_num    cmt

  ------------------------------------------------------------------------------------------------

   0x00    9    0x00  0x11d2  0xffff  0x0000.00ae9241  0x02000010  0x0000.000.00000000  0x00000001   0x00000000  1402531961

   0x01    9    0x00  0x11cf  0x001a  0x0000.00ae90f1  0x0200000b  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x02    9    0x00  0x11d2  0x0016  0x0000.00ae9199  0x0200001c  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x03    9    0x00  0x11d4  0x0007  0x0000.00ae91f4  0x02000010  0x0000.000.00000000  0x00000001   0x00000000  1402531756

   0x04    9    0x00  0x11cd  0x0006  0x0000.00ae90af  0x00000000  0x0000.000.00000000  0x00000000   0x00000000  1402531591

   0x05    9    0x00  0x11d0  0x000e  0x0000.00ae915a  0x02000017  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x06    9    0x00  0x11d2  0x0019  0x0000.00ae90b2  0x0200001f  0x0000.000.00000000  0x00000001   0x00000000  1402531591

   0x07    9    0x00  0x11d3  0x000d  0x0000.00ae91f6  0x02000010  0x0000.000.00000000  0x00000001   0x00000000  1402531756

   0x08    9    0x00  0x11d3  0x0014  0x0000.00ae911b  0x0200001b  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x09    9    0x00  0x11d2  0x000a  0x0000.00ae916f  0x0200000c  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x0a    9    0x00  0x11d3  0x0012  0x0000.00ae9179  0x0200000e  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x0b    9    0x00  0x11d0  0x0017  0x0000.00ae90d2  0x02000015  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x0c    9    0x00  0x11ce  0x001b  0x0000.00ae9145  0x02000013  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x0d    9    0x00  0x11d2  0x0000  0x0000.00ae91f8  0x02000010  0x0000.000.00000000  0x00000001   0x00000000  1402531756

   0x0e    9    0x00  0x11d1  0x0009  0x0000.00ae9164  0x0200000a  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x0f    9    0x00  0x11d0  0x0003  0x0000.00ae91ae  0x02000010  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x10    9    0x00  0x11d3  0x000b  0x0000.00ae90c7  0x02000013  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x11    9    0x00  0x11d4  0x0008  0x0000.00ae9111  0x02000019  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x12    9    0x00  0x11d0  0x001f  0x0000.00ae9184  0x02000018  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x13    9    0x00  0x11cd  0x001c  0x0000.00ae909d  0x0200001d  0x0000.000.00000000  0x00000001   0x00000000  1402531591

   0x14    9    0x00  0x11d1  0x0015  0x0000.00ae9126  0x0200001d  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x15    9    0x00  0x11d1  0x0020  0x0000.00ae9130  0x0200001f  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x16    9    0x00  0x11d1  0x000f  0x0000.00ae91a3  0x0200001e  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x17    9    0x00  0x11d1  0x0021  0x0000.00ae90dc  0x02000016  0x0000.000.00000000  0x00000002   0x00000000  1402531591

   0x18    9    0x00  0x11d0  0x0011  0x0000.00ae9106  0x0200000f  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x19    9    0x00  0x11d2  0x0010  0x0000.00ae90bd  0x02000011  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x1a    9    0x00  0x11d1  0x0018  0x0000.00ae90fc  0x0200000d  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x1b    9    0x00  0x11d3  0x0005  0x0000.00ae914f  0x02000015  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x1c    9    0x00  0x11d0  0x001d  0x0000.00ae90a3  0x0200001d  0x0000.000.00000000  0x00000001   0x00000000  1402531591

   0x1d    9    0x00  0x11d1  0x0004  0x0000.00ae90ad  0x00000000  0x0000.000.00000000  0x00000000   0x00000000  1402531591

   0x1e    9    0x00  0x11d1  0x0013  0x0000.00ae909b  0x0200001c  0x0000.000.00000000  0x00000001   0x00000000  1402531591

   0x1f    9    0x00  0x11d0  0x0002  0x0000.00ae918e  0x0200001a  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x20    9    0x00  0x11d2  0x000c  0x0000.00ae913b  0x02000011  0x0000.000.00000000  0x00000003   0x00000000  1402531591

   0x21    9    0x00  0x11d0  0x0001  0x0000.00ae90e7  0x02000009  0x0000.000.00000000  0x00000002   0x00000000  1402531591

update scott.tabnow1 set username='XS$NULL' where user_id=2147483638;

select XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN,to_char(START_SCNB,'xxxxxxxx') start_scn from v$transaction;

    XIDUSN    XIDSLOT     XIDSQN     UBAFIL     UBABLK     UBAREC     UBASQN START_SCN

---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------

         2         30       4562          8         16         25       6270    ae9241

alter system flush buffer_cache;

alter system dump datafile 8 block 16;

---data block dump的结果中摘录了Rec#0x19内容:

*-----------------------------

* Rec #0x19  slt: 0x1e  objn: 90344(0x000160e8)  objd: 90344  tblspc: 8(0x00000008)

*       Layer:  11 (Row)   opc: 1   rci 0x00

Undo type:  Regular undo    Begin trans    Last buffer split:  No

Temp Object:  No

Tablespace Undo:  No

rdba: 0x00000000Ext idx: 0

flg2: 0

*-----------------------------

uba: 0x02000010.187e.18 ctl max scn: 0x0000.00ae9095 prv tx scn: 0x0000.00ae909b

txn start scn: scn: 0x0000.00ae90b2 logon user: 0

 prev brb: 33554460 prev bcl: 0

KDO undo record:

KTB Redo

op: 0x04  ver: 0x01

compat bit: 4 (post-11) padding: 1

op: L  itl: xid:  0x0002.004.0000111f uba: 0x0200001a.177b.09

                      flg: C---    lkc:  0     scn: 0x0000.00ad9579

KDO Op code: URP row dependencies Disabled

  xtype: XA flags: 0x00000000  bdba: 0x010006f3  hdba: 0x010006f2

itli: 2  ispac: 0  maxfr: 4858

tabn: 0 slot: 0(0x0) flag: 0x2c lock: 0 ckix: 0

ncol: 3 nnew: 1 size: 2

col  0: [ 9]  58 53 24 4e 55 4c 4c 4c 4c

--58 53 24 4e 55 4c 4c 4c 4c转换为varchar2,得到修改前的拷贝

select utl_raw.cast_to_varchar2(replace('58 53 24 4e 55 4c 4c 4c 4c',' ')) from dual;

UTL_RAW.CAST_TO_VARCHAR2(REPLACE('5853244E554C4C4C4C',''))

--------------------------------------------------------------------------------

XS$NULLLL

alter system dump undo header "_SYSSMU2$"; 

--下面是undo header中有关事务控制和事务表的dump内容,slot 0x1e处于活动状态,0x020000108/16

  TRN CTL:: seq: 0x187e chd: 0x0009 ctl: 0x000e inc: 0x00000000 nfb: 0x0001

            mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)

            uba: 0x02000014.187e.13 scn: 0x0000.00ae92e6

index  state cflags  wrap#    uel         scn            dba            parent-xid    nub     stmt_num    cmt

  ------------------------------------------------------------------------------------------------

   0x00    9    0x00  0x11d4  0x0013  0x0000.00ae92f6  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x01    9    0x00  0x11d2  0x001a  0x0000.00ae9303  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x02    9    0x00  0x11d4  0x0016  0x0000.00ae92ed  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x03    9    0x00  0x11d6  0x0007  0x0000.00ae92f2  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x04    9    0x00  0x11d0  0x0006  0x0000.00ae92fa  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x05    9    0x00  0x11d3  0x000e  0x0000.00ae9310  0x02000014  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x06    9    0x00  0x11d5  0x0019  0x0000.00ae92fc  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x07    9    0x00  0x11d5  0x000d  0x0000.00ae92f4  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x08    9    0x00  0x11d6  0x0014  0x0000.00ae9308  0x02000014  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x09    9    0x00  0x11d4  0x000a  0x0000.00ae92e7  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x0a    9    0x00  0x11d5  0x0012  0x0000.00ae92e9  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x0b    9    0x00  0x11d3  0x0017  0x0000.00ae9300  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x0c    9    0x00  0x11d1  0x001b  0x0000.00ae930e  0x02000014  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x0d    9    0x00  0x11d4  0x0000  0x0000.00ae92f5  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x0e    9    0x00  0x11d4  0xffff  0x0000.00ae9311  0x02000014  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x0f    9    0x00  0x11d2  0x0003  0x0000.00ae92f0  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x10    9    0x00  0x11d6  0x000b  0x0000.00ae92ff  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x11    9    0x00  0x11d7  0x0008  0x0000.00ae9307  0x02000014  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x12    9    0x00  0x11d2  0x001f  0x0000.00ae92eb  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x13    9    0x00  0x11d0  0x001c  0x0000.00ae92f7  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x14    9    0x00  0x11d4  0x0015  0x0000.00ae930a  0x02000014  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x15    9    0x00  0x11d4  0x0020  0x0000.00ae930b  0x02000014  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x16    9    0x00  0x11d3  0x000f  0x0000.00ae92ee  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x17    9    0x00  0x11d4  0x0021  0x0000.00ae9301  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x18    9    0x00  0x11d3  0x0011  0x0000.00ae9306  0x02000014  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x19    9    0x00  0x11d5  0x0010  0x0000.00ae92fe  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x1a    9    0x00  0x11d4  0x0018  0x0000.00ae9304  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x1b    9    0x00  0x11d6  0x0005  0x0000.00ae930f  0x02000014  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x1c    9    0x00  0x11d3  0x001d  0x0000.00ae92f8  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x1d    9    0x00  0x11d4  0x0004  0x0000.00ae92f9  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x1e   10    0x80  0x11d2  0x0002  0x0000.00ae9241  0x02000010  0x0000.000.00000000  0x00000001   0x00000000  0

   0x1f    9    0x00  0x11d2  0x0002  0x0000.00ae92ec  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x20    9    0x00  0x11d5  0x000c  0x0000.00ae930c  0x02000014  0x0000.000.00000000  0x00000001   0x00000000  1402532191

   0x21    9    0x00  0x11d3  0x0001  0x0000.00ae9302  0x02000013  0x0000.000.00000000  0x00000001   0x00000000  1402532191

/////////////

//session 2:

/////////////

##scott用户登陆,注意这里不能用SYS用户登录,否则set transaction read only不起作用,记录下snapshot SCN的近似值

sqlplus scott/sdfg0987

select 'scn before read only: '||to_char(timestamp_to_scn(sysdate),'xxxxxxxx') from dual;

'SCNBEFOREREADONLY:'||TO_CHAR(T

-------------------------------

scn before read only:    ae931d

set transaction read only;

##记录当前会话的统计信息,system.clean_stat里存放了与本次测试有关的统计

select st.name,my.value from system.clean_stat st,v$mystat my where my.statistic#=st.statistic#;

        NAME                                                                  VALUE

---------------------------------------------------------------- ----------

commit cleanouts                                                          0

commit cleanouts successfully completed                                   0

redo KB read for transport                                                0

file io wait time                                                     27395

gc cr blocks served                                                       0

transaction tables consistent reads - undo records applied                0

transaction tables consistent read rollbacks                              0

cleanouts only - consistent read gets                                     0

cleanouts and rollbacks - consistent read gets                            0

immediate (CR) block cleanout applications                                0

deferred (CURRENT) block cleanout applications                            0

/////////////

//session 1:

/////////////

commit;

      

alter system flush buffer_cache;

alter system dump datafile 4 block 1779;

--摘录data block dump结果中Itl有关的部分,事务使用0x02槽位,xidubaundo header 0x1e事务槽中的值匹配,这里很明显这里发生了delayed block clean out

  Itl           Xid                  Uba         Flag  Lck        Scn/Fsc

0x01   0x0002.000.000011d2  0x02000010.187e.18  C---    0  scn 0x0000.00ae9241

0x02   0x0002.01e.000011d2  0x02000010.187e.19  ----    1  fsc 0x0002.00000000

0x03   0x0002.017.00001139  0x02000011.1788.1f  C---    0  scn 0x0000.00adb1b6

/////////////

//session 3:

/////////////

##db_block_size=8k的情况下,undo segment中有34slot,执行下面的存储过程完成340次的update,平均每个slot将被覆盖10

@proc1.sql

##执行后输出历次所使用的xiduba信息

--1轮覆盖

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :1  2,31,4563,8,20,27,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :2  2,2,4565,8,20,28,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :3  2,22,4564,8,20,29,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :4  2,15,4563,8,20,30,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :5  2,3,4567,8,20,31,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :6  2,7,4566,8,20,32,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :7  2,13,4565,8,20,33,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :8  2,0,4565,8,20,34,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :9  2,19,4561,8,20,35,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :10  2,28,4564,8,20,36,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :11  2,29,4565,8,20,37,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :12  2,4,4561,8,20,38,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :13  2,6,4566,8,20,39,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :14  2,25,4566,8,20,40,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :15  2,16,4567,8,20,41,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :16  2,11,4564,8,20,42,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :17  2,23,4565,8,20,43,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :18  2,33,4564,8,20,44,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :19  2,1,4563,8,20,45,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :20  2,26,4565,8,20,46,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :21  2,24,4564,8,20,47,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :22  2,17,4568,8,16,26,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :23  2,8,4567,8,16,27,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :24  2,20,4565,8,16,28,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :25  2,21,4565,8,16,29,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :26  2,32,4566,8,16,30,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :27  2,12,4562,8,16,31,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :28  2,27,4567,8,16,32,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :29  2,5,4564,8,16,33,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :30  2,14,4565,8,16,34,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :31  2,30,4563,8,16,35,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :32  2,9,4566,8,16,36,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :33  2,10,4567,8,21,1,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :34  2,18,4564,8,21,2,6270

。。。。省略了部分

--10轮覆盖

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :307  2,31,4572,8,14,3,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :308  2,2,4574,8,14,4,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :309  2,22,4573,8,14,5,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :310  2,15,4572,8,14,6,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :311  2,3,4576,8,14,7,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :312  2,7,4575,8,14,8,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :313  2,13,4574,8,14,9,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :314  2,0,4574,8,14,10,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :315  2,19,4570,8,14,11,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :316  2,28,4573,8,14,12,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :317  2,29,4574,8,14,13,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :318  2,4,4570,8,14,14,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :319  2,6,4575,8,14,15,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :320  2,25,4575,8,14,16,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :321  2,16,4576,8,14,17,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :322  2,11,4573,8,14,18,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :323  2,23,4574,8,14,19,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :324  2,33,4573,8,14,20,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :325  2,1,4572,8,14,21,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :326  2,26,4574,8,14,22,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :327  2,24,4573,8,14,23,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :328  2,17,4577,8,14,24,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :329  2,8,4576,8,14,25,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :330  2,20,4574,8,14,26,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :331  2,21,4574,8,14,27,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :332  2,32,4575,8,14,28,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :333  2,12,4571,8,14,29,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :334  2,27,4576,8,14,30,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :335  2,5,4573,8,14,31,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :336  2,14,4574,8,14,32,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :337  2,30,4572,8,14,33,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :338  2,9,4575,8,14,34,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :339  2,10,4576,8,15,1,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :340  2,18,4573,8,15,2,6271

alter system flush buffer_cache;

alter system dump undo header "_SYSSMU2$";

--undo header dump结果,发现slot0x1e wrap#0x11d2->0x11dc,的确覆盖了10次,control scn00ae96dc远大于 Session 2查询开始时的scnae931d,也预示着Session 2的查询将触发undo事务表回滚

TRN CTL:: seq: 0x187f chd: 0x001f ctl: 0x0012 inc: 0x00000000 nfb: 0x0001

            mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)

            uba: 0x0200000f.187f.02 scn: 0x0000.00ae96dc

  TRN TBL::

   index  state cflags  wrap#    uel         scn            dba            parent-xid    nub     stmt_num    cmt

  ------------------------------------------------------------------------------------------------

   0x00    9    0x00  0x11de  0x0013  0x0000.00ae96f4  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x01    9    0x00  0x11dc  0x001a  0x0000.00ae9715  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x02    9    0x00  0x11de  0x0016  0x0000.00ae96e2  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x03    9    0x00  0x11e0  0x0007  0x0000.00ae96eb  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x04    9    0x00  0x11da  0x0006  0x0000.00ae9700  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x05    9    0x00  0x11dd  0x000e  0x0000.00ae9733  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x06    9    0x00  0x11df  0x0019  0x0000.00ae9703  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x07    9    0x00  0x11df  0x000d  0x0000.00ae96ee  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x08    9    0x00  0x11e0  0x0014  0x0000.00ae9721  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x09    9    0x00  0x11df  0x000a  0x0000.00ae973c  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x0a    9    0x00  0x11e0  0x0012  0x0000.00ae973f  0x0200000f  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x0b    9    0x00  0x11dd  0x0017  0x0000.00ae970c  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x0c    9    0x00  0x11db  0x001b  0x0000.00ae972d  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x0d    9    0x00  0x11de  0x0000  0x0000.00ae96f1  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x0e    9    0x00  0x11de  0x001e  0x0000.00ae9736  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x0f    9    0x00  0x11dc  0x0003  0x0000.00ae96e8  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x10    9    0x00  0x11e0  0x000b  0x0000.00ae9709  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x11    9    0x00  0x11e1  0x0008  0x0000.00ae971e  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x12    9    0x00  0x11dd  0xffff  0x0000.00ae9742  0x0200000f  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x13    9    0x00  0x11da  0x001c  0x0000.00ae96f7  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x14    9    0x00  0x11de  0x0015  0x0000.00ae9724  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x15    9    0x00  0x11de  0x0020  0x0000.00ae9727  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x16    9    0x00  0x11dd  0x000f  0x0000.00ae96e5  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x17    9    0x00  0x11de  0x0021  0x0000.00ae970f  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x18    9    0x00  0x11dd  0x0011  0x0000.00ae971b  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x19    9    0x00  0x11df  0x0010  0x0000.00ae9706  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x1a    9    0x00  0x11de  0x0018  0x0000.00ae9718  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x1b    9    0x00  0x11e0  0x0005  0x0000.00ae9730  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x1c    9    0x00  0x11dd  0x001d  0x0000.00ae96fa  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x1d    9    0x00  0x11de  0x0004  0x0000.00ae96fd  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x1e    9    0x00  0x11dc  0x0009  0x0000.00ae9739  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x1f    9    0x00  0x11dc  0x0002  0x0000.00ae96df  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x20    9    0x00  0x11df  0x000c  0x0000.00ae972a  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

   0x21    9    0x00  0x11dd  0x0001  0x0000.00ae9712  0x0200000e  0x0000.000.00000000  0x00000001   0x00000000  1402532364

##dump 所有的undo block,以便后面作分析

alter system dump datafile 8 block min 9 block max 31;

/////////////

//session 2:

/////////////

##遍历scott.tabnow1表,查到了session 1修改前的拷贝

select * from scott.tabnow1;

USERNAME                          USER_ID CREATED

------------------------------ ---------- ------------

XS$NULLLL                      2147483638 21-OCT-11

NEWUSER                                84 12-MAR-14

SCOTTTTT                               83 21-OCT-11

OWBSYS_AUDIT                           82 21-OCT-11

OWBSYS                                 78 21-OCT-11

APEX                                   77 21-OCT-11

APEX_PUBLIC                            75 21-OCT-11

FLOWS_FILE                             74 21-OCT-11

MGMT_VIEW                              73 21-OCT-11

DDD                                    34 28-MAY-14

##会话中事务表一致性读相关的统计值增加

select st.name,my.value from system.clean_stat st,v$mystat my where my.statistic#=st.statistic#;

NAME                                                                  VALUE

---------------------------------------------------------------- ----------

commit cleanouts                                                          0

commit cleanouts successfully completed                                   0

redo KB read for transport                                                0

file io wait time                                                     40974

gc cr blocks served                                                       0

transaction tables consistent reads - undo records applied              310

transaction tables consistent read rollbacks                              1

cleanouts only - consistent read gets                                     0

cleanouts and rollbacks - consistent read gets                            1

immediate (CR) block cleanout applications                                1

deferred (CURRENT) block cleanout applications                            0

针对上述测试结果的分析:

Undo header 事务表中的每个slot被覆盖多达10次,session 2还能正常返回scott.tabnow1表修改前的记录,就是利用了undo事务表的回滚机制,为了实现这个回滚:当新的事务开始使用某个undo事务表槽之前会将事务表TRN CTL部分的scnuba两个值作为ctl max scnuba字段保存到新事务所拥有的undo block里,也会将这个事务表槽中的scndba两个值作为prv tx scnprev brb字段保存到新事务所拥有的undo block里,例如session 1 中事务使用的uba8/16  Rec #0x19

*-----------------------------

* Rec #0x19  slt: 0x1e  objn: 90344(0x000160e8)  objd: 90344  tblspc: 8(0x00000008)

*       Layer:  11 (Row)   opc: 1   rci 0x00

Undo type:  Regular undo    Begin trans    Last buffer split:  No

Temp Object:  No

Tablespace Undo:  No

rdba: 0x00000000Ext idx: 0

flg2: 0

*-----------------------------

uba: 0x02000010.187e.18 ctl max scn: 0x0000.00ae9095 prv tx scn: 0x0000.00ae909b

txn start scn: scn: 0x0000.00ae90b2 logon user: 0

 prev brb: 33554460 prev bcl: 0

KDO undo record:

KTB Redo

op: 0x04  ver: 0x01

compat bit: 4 (post-11) padding: 1

op: L  itl: xid:  0x0002.004.0000111f uba: 0x0200001a.177b.09

                      flg: C---    lkc:  0     scn: 0x0000.00ad9579

KDO Op code: URP row dependencies Disabled

  xtype: XA flags: 0x00000000  bdba: 0x010006f3  hdba: 0x010006f2

itli: 2  ispac: 0  maxfr: 4858

tabn: 0 slot: 0(0x0) flag: 0x2c lock: 0 ckix: 0

ncol: 3 nnew: 1 size: 2

col  0: [ 9]  58 53 24 4e 55 4c 4c 4c 4c

上述dumpuba: 0x02000010.187e.18 ctl max scn: 0x0000.00ae9095正是来自于事务开始前undo headerTRN CTL部分所包含的uba: 0x02000010.187e.18 scn: 0x0000.00ae9095,而prv tx scn0x0000.00ae909b prev brb33554460 则分别等于事务开始前slot 0x1e 所对应的scn00ae909bdba0x0200001c(转换成10进制就是33554460)。只有事务的首条undo记录才会保留上一版本的undo信息。将相关的undo记录串起来就可以完整的回放事务表所发生过的变更,下面较为直观的方式说明一下undo 记录间的指向关系,还是以proc1.sql里前三个事务为例,它们所使用的xiduba如下:

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :  2,31,4563,8,20,27,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :  2,2,4565,8,20,28,6270

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :  2,22,4564,8,20,29,6270

Undo record的记录是后修改的指向先修改的,所以依次dump block 8/20 Rec #0x1dRec #0x1c Rec #0x1b的记录,仅将相关的内容摘录下来:

*-----------------------------

* Rec #0x1d  slt: 0x16  objn: 89731(0x00015e83)  objd: 89731  tblspc: 8(0x00000008)

*       Layer:  11 (Row)   opc: 1   rci 0x00

Undo type:  Regular undo    Begin trans    Last buffer split:  No

Temp Object:  No

Tablespace Undo:  No

rdba: 0x00000000Ext idx: 0

flg2: 0

*-----------------------------

uba: 0x02000014.187e.1c ctl max scn: 0x0000.00ae92ed prv tx scn: 0x0000.00ae92ee

txn start scn: scn: 0x0000.00ae9357 logon user: 0

 prev brb: 33554451 prev bcl: 0

*-----------------------------

* Rec #0x1c  slt: 0x02  objn: 89731(0x00015e83)  objd: 89731  tblspc: 8(0x00000008)

*       Layer:  11 (Row)   opc: 1   rci 0x00

Undo type:  Regular undo    Begin trans    Last buffer split:  No

Temp Object:  No

Tablespace Undo:  No

rdba: 0x00000000Ext idx: 0

flg2: 0

*-----------------------------

uba: 0x02000014.187e.1b ctl max scn: 0x0000.00ae92ec prv tx scn: 0x0000.00ae92ed

txn start scn: scn: 0x0000.00ae9354 logon user: 0

 prev brb: 33554451 prev bcl: 0

*-----------------------------

* Rec #0x1b  slt: 0x1f  objn: 89731(0x00015e83)  objd: 89731  tblspc: 8(0x00000008)

*       Layer:  11 (Row)   opc: 1   rci 0x00

Undo type:  Regular undo    Begin trans    Last buffer split:  No

Temp Object:  No

Tablespace Undo:  No

rdba: 0x00000000Ext idx: 0

flg2: 0

*-----------------------------

uba: 0x02000014.187e.18 ctl max scn: 0x0000.00ae92eb prv tx scn: 0x0000.00ae92ec

txn start scn: scn: 0x0000.00000000 logon user: 0

 prev brb: 33554451 prev bcl: 0

通过这三个undo Record能够映射得到前一时刻的undo事务表,假设T3>T2>T1>T0,以下图示能够直观的展现这一映射关系:

上面的图能够帮助我们理解oracle是如何实现事务表的回滚,只要undo block不被覆盖,就能回滚得到足够旧的事务表。

具备了上述知识点后,我们分析一下session 2是如何成功遍历scott.tabnow1表的:

(1)    Session 2select语句执行时的snapshot scn近似等于ae931d

(2)    访问rdba4/1779 时发现Itl列表里slot 0x02还处于活动状态,且没有commit scn,于是就到xid所指向的undo 事务表进一步查询事务是否提交,slot 0x1estate=9表示事务已经提交,但提交时的wrap#值为0x11dc远大于0x11d2,且undo 事务表头的control scnae96dc远大于snapshot scn: ae931d

(3)    Oracle判断事务表槽已slot 0x1e已经被覆盖,需要回滚事务表,回滚的起点是8/14 Rec #0x21,这个Recordproc1.sql中第337transaction所使用的undo record,因为正是这个transaction完成了对undo slot 0x1e的最后一次覆盖

(4)    接下来将如上图所示,oracle一步一步的对事务表进行回滚,每重构出一个事务表的版本后,将事务表头部的control scnsnapshot scn进行比较,如果snapshot scn则继续进行回滚,直到snapshot scn>=control scn而且wrap#的值等于0x11d2,事务表才回滚完毕,从undo record 8/16  Rec #0x19里读出修改前的值:

select utl_raw.cast_to_varchar2(replace('58 53 24 4e 55 4c 4c 4c 4c',' ')) from dual;

UTL_RAW.CAST_TO_VARCHAR2(REPLACE('5853244E554C4C4C4C',''))

--------------------------------------------------------------------------------

XS$NULLLL

Session 2实现一致性读的两个统计信息:

NAME                                                                  VALUE

---------------------------------------------------------------- ----------

transaction tables consistent reads - undo records applied              310

transaction tables consistent read rollbacks                              1

transaction tables consistent reads - undo records applied              310

表示为了回滚事务表应用了多少undo records,这里为何是310,暂无法证实,我本来认为应该是338

transaction tables consistent read rollbacks                              1

表示事务表发生了一次回滚的动作

之前我们曾经在session 3里通过alter system dump datafile 8 block min 9 block max 31将所有的undo block dump出来,现在回过头来看一下dump的结果在undo Record 8/17 Rec #0x1里找到了uba: 0x02000010.187e.19,即存放修改前拷贝的undo record8/16  Rec #0x19,说明这个undo record还在undo chain

*-----------------------------

* Rec #0x1  slt: 0x13  objn: 270(0x0000010e)  objd: 268  tblspc: 1(0x00000001)

*       Layer:  11 (Row)   opc: 1   rci 0x00

Undo type:  Regular undo    Begin trans    Last buffer split:  No

Temp Object:  No

Tablespace Undo:  No

rdba: 0x00000000Ext idx: 0

flg2: 0

*-----------------------------

uba: 0x02000010.187e.19 ctl max scn: 0x0000.00ae909b prv tx scn: 0x0000.00ae909d

txn start scn: scn: 0x0000.00ae9294 logon user: 0

 prev brb: 33554461 prev bcl: 0

KDO undo record:

KTB Redo

op: 0x04  ver: 0x01

compat bit: 4 (post-11) padding: 1

op: L  itl: xid:  0x0002.006.000011d2 uba: 0x0200001f.1877.01

                      flg: C---    lkc:  0     scn: 0x0000.00ae90b2

KDO Op code: DRP row dependencies Disabled

  xtype: XA flags: 0x00000000  bdba: 0x00810de8  hdba: 0x00800192

itli: 2  ispac: 0  maxfr: 4858

tabn: 1 slot: 5(0x5)

##进一步dump 8/16  Rec #0x19的内容,可以看到修改前的内容还在,所以session 2能完成表的遍历

*-----------------------------

* Rec #0x19  slt: 0x1e  objn: 90344(0x000160e8)  objd: 90344  tblspc: 8(0x00000008)

*       Layer:  11 (Row)   opc: 1   rci 0x00

Undo type:  Regular undo    Begin trans    Last buffer split:  No

Temp Object:  No

Tablespace Undo:  No

rdba: 0x00000000Ext idx: 0

flg2: 0

*-----------------------------

uba: 0x02000010.187e.18 ctl max scn: 0x0000.00ae9095 prv tx scn: 0x0000.00ae909b

txn start scn: scn: 0x0000.00ae90b2 logon user: 0

 prev brb: 33554460 prev bcl: 0

KDO undo record:

KTB Redo

op: 0x04  ver: 0x01

compat bit: 4 (post-11) padding: 1

op: L  itl: xid:  0x0002.004.0000111f uba: 0x0200001a.177b.09

                      flg: C---    lkc:  0     scn: 0x0000.00ad9579

KDO Op code: URP row dependencies Disabled

  xtype: XA flags: 0x00000000  bdba: 0x010006f3  hdba: 0x010006f2

itli: 2  ispac: 0  maxfr: 4858

tabn: 0 slot: 0(0x0) flag: 0x2c lock: 0 ckix: 0

ncol: 3 nnew: 1 size: 2

col  0: [ 9]  58 53 24 4e 55 4c 4c 4c 4c

/////////////

//session 4:

/////////////

##proc1.sql脚本的循环次数作略微调整后,分别在循环34次、循环68次、循环102次的情况下,继续对事务槽作覆盖,平均每个事务槽再被覆盖6次,执行调整后的proc1.sql,输出如下:

--proc1.sql调整为循环34次时的输出:

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :1  2,2,4575,8,15,17,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :2  2,22,4574,8,15,18,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :3  2,15,4573,8,15,19,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :4  2,3,4577,8,15,20,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :5  2,7,4576,8,15,21,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :6  2,13,4575,8,15,22,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :7  2,0,4575,8,15,23,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :8  2,19,4571,8,15,24,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :9  2,28,4574,8,15,25,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :10  2,29,4575,8,15,26,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :11  2,4,4571,8,15,27,6271

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :12  2,6,4576,8,24,1,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :13  2,25,4576,8,24,2,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :14  2,16,4577,8,24,3,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :15  2,11,4574,8,24,4,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :16  2,23,4575,8,24,5,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :17  2,33,4574,8,24,6,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :18  2,1,4573,8,24,7,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :19  2,26,4575,8,24,8,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :20  2,24,4574,8,24,9,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :21  2,17,4578,8,24,10,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :22  2,8,4577,8,24,11,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :23  2,20,4575,8,24,12,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :24  2,21,4575,8,24,13,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :25  2,32,4576,8,24,14,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :26  2,12,4572,8,24,15,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :27  2,27,4577,8,24,16,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :28  2,5,4574,8,24,17,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :29  2,14,4575,8,24,18,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :30  2,30,4573,8,24,19,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :31  2,9,4576,8,24,20,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :32  2,10,4577,8,24,21,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :33  2,18,4574,8,24,22,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :34  2,31,4574,8,24,23,6272

--proc1.sql调整为循环68次时的输出:

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :1  2,21,4576,8,26,1,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :2  2,32,4577,8,26,2,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :3  2,12,4573,8,26,3,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :4  2,27,4578,8,26,4,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :5  2,5,4575,8,26,5,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :6  2,14,4576,8,26,6,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :7  2,30,4574,8,26,7,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :8  2,9,4577,8,26,8,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :9  2,10,4578,8,26,9,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :10  2,18,4575,8,26,10,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :11  2,31,4575,8,26,11,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :12  2,2,4577,8,26,12,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :13  2,22,4576,8,26,13,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :14  2,15,4575,8,26,14,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :15  2,3,4579,8,26,15,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :16  2,7,4578,8,26,16,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :17  2,13,4577,8,26,17,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :18  2,0,4577,8,26,18,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :19  2,19,4573,8,26,19,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :20  2,28,4576,8,26,20,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :21  2,29,4577,8,26,21,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :22  2,4,4573,8,26,22,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :23  2,6,4578,8,26,23,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :24  2,25,4578,8,26,24,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :25  2,16,4579,8,26,25,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :26  2,11,4576,8,26,26,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :27  2,23,4577,8,26,27,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :28  2,33,4576,8,26,28,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :29  2,1,4575,8,26,29,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :30  2,26,4577,8,26,30,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :31  2,24,4576,8,26,31,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :32  2,17,4580,8,26,32,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :33  2,8,4579,8,26,33,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :34  2,20,4577,8,26,34,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :35  2,21,4577,8,27,1,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :36  2,32,4578,8,27,2,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :37  2,12,4574,8,27,3,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :38  2,27,4579,8,27,4,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :39  2,5,4576,8,27,5,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :40  2,14,4577,8,27,6,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :41  2,30,4575,8,27,7,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :42  2,9,4578,8,27,8,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :43  2,10,4579,8,27,9,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :44  2,18,4576,8,27,10,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :45  2,31,4576,8,27,11,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :46  2,2,4578,8,27,12,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :47  2,22,4577,8,27,13,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :48  2,15,4576,8,27,14,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :49  2,3,4580,8,27,15,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :50  2,7,4579,8,27,16,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :51  2,13,4578,8,27,17,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :52  2,0,4578,8,27,18,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :53  2,19,4574,8,27,19,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :54  2,28,4577,8,27,20,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :55  2,29,4578,8,27,21,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :56  2,4,4574,8,27,22,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :57  2,6,4579,8,27,23,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :58  2,25,4579,8,27,24,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :59  2,16,4580,8,27,25,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :60  2,11,4577,8,27,26,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :61  2,23,4578,8,27,27,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :62  2,33,4577,8,27,28,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :63  2,1,4576,8,27,29,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :64  2,26,4578,8,27,30,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :65  2,24,4577,8,27,31,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :66  2,17,4581,8,27,32,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :67  2,8,4580,8,27,33,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :68  2,20,4578,8,27,34,6272

--proc1.sql调整为循环102次时的输出:

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :1  2,21,4578,8,28,1,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :2  2,32,4579,8,28,2,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :3  2,12,4575,8,28,3,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :4  2,27,4580,8,28,4,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :5  2,5,4577,8,28,5,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :6  2,14,4578,8,28,6,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :7  2,30,4576,8,28,7,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :8  2,9,4579,8,28,8,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :9  2,10,4580,8,28,9,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :10  2,18,4577,8,28,10,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :11  2,31,4577,8,28,11,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :12  2,2,4579,8,28,12,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :13  2,22,4578,8,28,13,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :14  2,15,4577,8,28,14,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :15  2,3,4581,8,28,15,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :16  2,7,4580,8,28,16,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :17  2,13,4579,8,28,17,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :18  2,0,4579,8,28,18,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :19  2,19,4575,8,28,19,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :20  2,28,4578,8,28,20,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :21  2,29,4579,8,28,21,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :22  2,4,4575,8,28,22,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :23  2,6,4580,8,28,23,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :24  2,25,4580,8,28,24,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :25  2,16,4581,8,28,25,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :26  2,11,4578,8,28,26,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :27  2,23,4579,8,28,27,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :28  2,33,4578,8,28,28,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :29  2,1,4577,8,28,29,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :30  2,26,4579,8,28,30,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :31  2,24,4578,8,28,31,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :32  2,17,4582,8,28,32,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :33  2,8,4581,8,28,33,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :34  2,20,4579,8,28,34,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :35  2,21,4579,8,29,1,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :36  2,32,4580,8,29,2,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :37  2,12,4576,8,29,3,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :38  2,27,4581,8,29,4,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :39  2,5,4578,8,29,5,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :40  2,14,4579,8,29,6,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :41  2,30,4577,8,29,7,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :42  2,9,4580,8,29,8,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :43  2,10,4581,8,29,9,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :44  2,18,4578,8,29,10,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :45  2,31,4578,8,29,11,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :46  2,2,4580,8,29,12,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :47  2,22,4579,8,29,13,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :48  2,15,4578,8,29,14,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :49  2,3,4582,8,29,15,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :50  2,7,4581,8,29,16,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :51  2,13,4580,8,29,17,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :52  2,0,4580,8,29,18,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :53  2,19,4576,8,29,19,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :54  2,28,4579,8,29,20,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :55  2,29,4580,8,29,21,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :56  2,4,4576,8,29,22,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :57  2,6,4581,8,29,23,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :58  2,25,4581,8,29,24,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :59  2,16,4582,8,29,25,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :60  2,11,4579,8,29,26,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :61  2,23,4580,8,29,27,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :62  2,33,4579,8,29,28,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :63  2,1,4578,8,29,29,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :64  2,26,4580,8,29,30,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :65  2,24,4579,8,29,31,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :66  2,17,4583,8,29,32,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :67  2,8,4582,8,29,33,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :68  2,20,4580,8,29,34,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :69  2,21,4580,8,30,1,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :70  2,32,4581,8,30,2,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :71  2,12,4577,8,30,3,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :72  2,27,4582,8,30,4,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :73  2,5,4579,8,30,5,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :74  2,14,4580,8,30,6,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :75  2,30,4578,8,30,7,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :76  2,9,4581,8,30,8,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :77  2,10,4582,8,30,9,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :78  2,18,4579,8,30,10,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :79  2,31,4579,8,30,11,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :80  2,2,4581,8,30,12,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :81  2,22,4580,8,30,13,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :82  2,15,4579,8,30,14,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :83  2,3,4583,8,30,15,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :84  2,7,4582,8,30,16,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :85  2,13,4581,8,30,17,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :86  2,0,4581,8,30,18,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :87  2,19,4577,8,30,19,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :88  2,28,4580,8,30,20,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :89  2,29,4581,8,30,21,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :90  2,4,4577,8,30,22,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :91  2,6,4582,8,30,23,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :92  2,25,4582,8,30,24,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :93  2,16,4583,8,30,25,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :94  2,11,4580,8,30,26,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :95  2,23,4581,8,30,27,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :96  2,33,4580,8,30,28,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :97  2,1,4579,8,30,29,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :98  2,26,4581,8,30,30,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :99  2,24,4580,8,30,31,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :100  2,17,4584,8,30,32,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :101  2,8,4583,8,30,34,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :102  2,20,4581,8,30,35,6272

/////////////

//session 2:

/////////////

##session 4对每个事务槽各覆盖6遍的基础上,再次遍历scott.tabnow1表,依然能查到scott.tabnow1修改前的拷贝

select * from scott.tabnow1;

USERNAME                          USER_ID CREATED

------------------------------ ---------- ------------

XS$NULLLL                      2147483638 21-OCT-11

NEWUSER                                84 12-MAR-14

SCOTTTTT                               83 21-OCT-11

OWBSYS_AUDIT                           82 21-OCT-11

OWBSYS                                 78 21-OCT-11

APEX                                   77 21-OCT-11

APEX_PUBLIC                            75 21-OCT-11

FLOWS_FILE                             74 21-OCT-11

MGMT_VIEW                              73 21-OCT-11

DDD                                    34 28-MAY-14

session 4再次尝试覆盖的过程中,通过proc1.sql执行输出的xiduba信息获知undo record 8/25 Rec#0x19并没有被使用到.

##dump 所有undo

alter system dump datafile 8 block min 9 block max 31;

##在生成的dump文件中,寻找到8/25 Rec#0x19对应的uba地址:02000010.187e.19仍然包含在8/17 Rec#0x1中,且8/25 Rec#0x19里仍存有修改前的数据拷贝,这样既确保事务表正常回滚,也确保修改前的拷贝能被正常读取

--8/17 Rec #0x1包含有到uba: 0x02000010.187e.19的指向

*-----------------------------

* Rec #0x1  slt: 0x13  objn: 270(0x0000010e)  objd: 268  tblspc: 1(0x00000001)

*       Layer:  11 (Row)   opc: 1   rci 0x00

Undo type:  Regular undo    Begin trans    Last buffer split:  No

Temp Object:  No

Tablespace Undo:  No

rdba: 0x00000000Ext idx: 0

flg2: 0

*-----------------------------

uba: 0x02000010.187e.19 ctl max scn: 0x0000.00ae909b prv tx scn: 0x0000.00ae909d

txn start scn: scn: 0x0000.00ae9294 logon user: 0

 prev brb: 33554461 prev bcl: 0

KDO undo record:

KTB Redo

op: 0x04  ver: 0x01

compat bit: 4 (post-11) padding: 1

op: L  itl: xid:  0x0002.006.000011d2 uba: 0x0200001f.1877.01

                      flg: C---    lkc:  0     scn: 0x0000.00ae90b2

KDO Op code: DRP row dependencies Disabled

  xtype: XA flags: 0x00000000  bdba: 0x00810de8  hdba: 0x00800192

itli: 2  ispac: 0  maxfr: 4858

tabn: 1 slot: 5(0x5)

--8/25 Rec#0x19包含有数据修改前的拷贝

*-----------------------------

* Rec #0x19  slt: 0x1e  objn: 90344(0x000160e8)  objd: 90344  tblspc: 8(0x00000008)

*       Layer:  11 (Row)   opc: 1   rci 0x00

Undo type:  Regular undo    Begin trans    Last buffer split:  No

Temp Object:  No

Tablespace Undo:  No

rdba: 0x00000000Ext idx: 0

flg2: 0

*-----------------------------

uba: 0x02000010.187e.18 ctl max scn: 0x0000.00ae9095 prv tx scn: 0x0000.00ae909b

txn start scn: scn: 0x0000.00ae90b2 logon user: 0

 prev brb: 33554460 prev bcl: 0

KDO undo record:

KTB Redo

op: 0x04  ver: 0x01

compat bit: 4 (post-11) padding: 1

op: L  itl: xid:  0x0002.004.0000111f uba: 0x0200001a.177b.09

                      flg: C---    lkc:  0     scn: 0x0000.00ad9579

KDO Op code: URP row dependencies Disabled

  xtype: XA flags: 0x00000000  bdba: 0x010006f3  hdba: 0x010006f2

itli: 2  ispac: 0  maxfr: 4858

tabn: 0 slot: 0(0x0) flag: 0x2c lock: 0 ckix: 0

ncol: 3 nnew: 1 size: 2

col  0: [ 9]  58 53 24 4e 55 4c 4c 4c 4c

select utl_raw.cast_to_varchar2(replace('58 53 24 4e 55 4c 4c 4c 4c',' ')) from dual;

UTL_RAW.CAST_TO_VARCHAR2(REPLACE('5853244E554C4C4C4C',''))

--------------------------------------------------------------------------------

XS$NULLLL

/////////////

//session 4:

/////////////

##下面再次调用proc1.sql,循环340次,这才形成了致命一击,proc1.sql输出如下:

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :1  2,21,4581,8,31,2,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :2  2,32,4582,8,31,3,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :3  2,12,4578,8,31,4,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :4  2,27,4583,8,31,5,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :5  2,5,4580,8,31,6,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :6  2,14,4581,8,31,7,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :7  2,30,4579,8,31,8,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :8  2,9,4582,8,31,9,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :9  2,10,4583,8,31,10,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :10  2,18,4580,8,31,11,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :11  2,31,4580,8,31,12,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :12  2,2,4582,8,31,13,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :13  2,22,4581,8,31,14,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :14  2,15,4580,8,31,15,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :15  2,3,4584,8,31,16,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :16  2,7,4583,8,31,17,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :17  2,13,4582,8,31,18,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :18  2,0,4582,8,31,19,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :19  2,19,4578,8,31,20,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :20  2,28,4581,8,31,21,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :21  2,29,4582,8,31,22,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :22  2,4,4578,8,31,23,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :23  2,6,4583,8,31,24,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :24  2,25,4583,8,31,25,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :25  2,16,4584,8,31,26,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :26  2,11,4581,8,31,27,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :27  2,23,4582,8,31,28,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :28  2,33,4581,8,31,29,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :29  2,1,4580,8,31,30,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :30  2,26,4582,8,31,31,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :31  2,24,4581,8,31,32,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :32  2,17,4585,8,31,33,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :33  2,8,4584,8,31,34,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :34  2,20,4582,8,31,35,6272

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :35  2,21,4582,8,16,1,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :36  2,32,4583,8,16,2,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :37  2,12,4579,8,16,3,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :38  2,27,4584,8,16,4,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :39  2,5,4581,8,16,5,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :40  2,14,4582,8,16,6,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :41  2,30,4580,8,16,7,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :42  2,9,4583,8,16,8,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :43  2,10,4584,8,16,9,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :44  2,18,4581,8,16,10,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :45  2,31,4581,8,16,11,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :46  2,2,4583,8,16,12,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :47  2,22,4582,8,16,13,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :48  2,15,4581,8,16,14,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :49  2,3,4585,8,16,15,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :50  2,7,4584,8,16,16,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :51  2,13,4583,8,16,17,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :52  2,0,4583,8,16,18,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :53  2,19,4579,8,16,19,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :54  2,28,4582,8,16,20,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :55  2,29,4583,8,16,21,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :56  2,4,4579,8,16,22,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :57  2,6,4584,8,16,23,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :58  2,25,4584,8,16,24,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :59  2,16,4585,8,16,25,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :60  2,11,4582,8,16,26,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :61  2,23,4583,8,16,27,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :62  2,33,4582,8,16,28,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :63  2,1,4581,8,16,29,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :64  2,26,4583,8,16,30,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :65  2,24,4582,8,16,31,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :66  2,17,4586,8,16,32,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :67  2,8,4585,8,16,33,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :68  2,20,4583,8,16,34,6273

XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :69  2,21,4583,8,17,1,6273

。。。。。。省略了后面的271

##从上面的输出可以看到8/16 Rec #0x198/17 Rec#0x1先后被覆盖,前者包含数据修改前的拷贝,后者包含了事务槽回滚所需的uba信息,这时必然导致下面session 2遇到ORA-01555错误

/////////////

//session 2:

/////////////

##久违的ORA-01555错误终于来了

select * from scott.tabnow1

*

ERROR at line 1:

ORA-01555: snapshot too old: rollback segment number 2 with name "_SYSSMU2$"

too small

 

alter system dump datafile 8 block min 9 block max 31;

 

##把所有undo block dump到文件stest2_ora_29753578.trc

alter system dump datafile 8 block min 9 block max 31;

##trace文件中未能查到02000010.187e.19,意味着事务表不能回溯到足够旧的版本

cat stest2_ora_29753578.trc | grep 02000010.187e.19 | wc –l

0

##8/16 #0x19中的记录也已经被覆盖掉了,意味着即使事务表即使能够顺利回滚,但也找不到修改前的数据拷贝了

*-----------------------------

* Rec #0x19  slt: 0x10  objn: 89731(0x00015e83)  objd: 89731  tblspc: 8(0x00000008)

*       Layer:  11 (Row)   opc: 1   rci 0x00

Undo type:  Regular undo    Begin trans    Last buffer split:  No

Temp Object:  No

Tablespace Undo:  No

rdba: 0x00000000Ext idx: 0

flg2: 0

*-----------------------------

uba: 0x02000010.1881.18 ctl max scn: 0x0000.00ae9c40 prv tx scn: 0x0000.00ae9c43

txn start scn: scn: 0x0000.00ae9ca6 logon user: 0

 prev brb: 33554463 prev bcl: 0

KDO undo record:

KTB Redo

op: 0x04  ver: 0x01

compat bit: 4 (post-11) padding: 1

op: L  itl: xid:  0x0002.006.000011e8 uba: 0x02000010.1881.17

                      flg: C---    lkc:  0     scn: 0x0000.00ae9ca3

Array Update of 2 rows:

tabn: 0 slot: 0(0x0) flag: 0x2c lock: 0 ckix: 1

ncol: 1 nnew: 1 size: 0

KDO Op code:  21 row dependencies Disabled

  xtype: XAxtype KDO_KDOM2 flags: 0x00000080  bdba: 0x010005be  hdba: 0x010005ba

itli: 2  ispac: 0  maxfr: 4858

vect = 0

col  0: [ 2]  c1 3b

tabn: 0 slot: 1(0x1) flag: 0x2c lock: 0 ckix: 1

ncol: 1 nnew: 1 size: 0

KDO Op code:  21 row dependencies Disabled

  xtype: XAxtype KDO_KDOM2 flags: 0x00000080  bdba: 0x010005be  hdba: 0x010005ba

itli: 2  ispac: 0  maxfr: 4858

vect = 0

col  0: [ 2]  c1 3b

 

 

 

 

 

proc1.sql

///Proc1.sql///

set serveroutput on

declare

v_xidusn number;

v_xidslot number;

v_xidsqn number;

v_ubafil number;

v_ubablk number;

v_ubasqn number;

v_ubarec number;

v_cnt number:=0;

v_rownum number;

v_startscn varchar2(20);

v_rowid rowid;

begin

select to_char(timestamp_to_scn(sysdate),'xxxxxxxx') into v_startscn from dual;

dbms_output.put_line('START SCN:'||v_startscn);

for i in 1..340 loop

  update scott.t1 set id = i;

  select XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN into v_xidusn,v_xidslot,v_xidsqn,v_ubafil,v_ubablk,v_ubarec,v_ubasqn from v$transaction;

  v_cnt:=v_cnt+1;

  dbms_output.put_line('XIDUSN,XIDSLOT,XIDSQN,UBAFIL,UBABLK,UBAREC,UBASQN  :'||v_cnt||'  '||v_xidusn||','||v_xidslot||','||v_xidsqn||','||v_ubafil||','||v_ubablk||','||v_ubarec||','||v_ubasqn);

  commit;

end loop;

end;

/

 

来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/53956/viewspace-1269340/,如需转载,请注明出处,否则将追究法律责任。

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