undo transaction slot被覆盖引起ORA-01555的原理解析
undo transaction slot被覆盖引起ORA-01555的原理解析
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_fno和block_number；
Update一条记录，但不commit，记录下所使用的xid、uba信息
Session 2：
以非SYS用户连接执行：set transaction read only;
Session 1：
Commit;
Session 3：
对scott.t1表连续做update+commit操作
Session 2：
成功遍历scott.tabnow1表
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表
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256K的undotbs
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 segment里extent的分布情况，除去undo header所占据的block 8，block 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 block作dump；所有的行都在同一个block中
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$transaction;
XIDUSN XIDSLOT XIDSQN UBAFIL UBABLK UBAREC UBASQN START_SCN
---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------
2 30 4562 8 16 25 6270 ae9241
alter system flush buffer_cache;
alter system dump datafile 8 block 16;
---data block dump的结果中摘录了Rec#0x19内容：
*-----------------------------
* Rec #0x19 slt: 0x1e objn: 90344(0x000160e8) objd: 90344 tblspc: 8(0x00000008)
* Layer: 11 (Row) opc: 1 rci 0x00
Undo type: Regular undo Begin trans Last buffer split: No
Temp Object: No
Tablespace Undo: No
rdba: 0x00000000Ext idx: 0
flg2: 0
*-----------------------------
uba: 0x02000010.187e.18 ctl max scn: 0x0000.00ae9095 prv tx scn: 0x0000.00ae909b
txn start scn: scn: 0x0000.00ae90b2 logon user: 0
prev brb: 33554460 prev bcl: 0
KDO undo record:
KTB Redo
op: 0x04 ver: 0x01
compat bit: 4 (post-11) padding: 1
op: L itl: xid: 0x0002.004.0000111f uba: 0x0200001a.177b.09
flg: C--- lkc: 0 scn: 0x0000.00ad9579
KDO Op code: URP row dependencies Disabled
xtype: XA flags: 0x00000000 bdba: 0x010006f3 hdba: 0x010006f2
itli: 2 ispac: 0 maxfr: 4858
tabn: 0 slot: 0(0x0) flag: 0x2c lock: 0 ckix: 0
ncol: 3 nnew: 1 size: 2
col 0: [ 9] 58 53 24 4e 55 4c 4c 4c 4c
--将58 53 24 4e 55 4c 4c 4c 4c转换为varchar2，得到修改前的拷贝
select utl_raw.cast_to_varchar2(replace('58 53 24 4e 55 4c 4c 4c 4c',' ')) from dual;
UTL_RAW.CAST_TO_VARCHAR2(REPLACE('5853244E554C4C4C4C',''))
--------------------------------------------------------------------------------
XS$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，0x02000010即8/16
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:
/////////////
##用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，xid、uba与undo 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34个slot，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次
@proc1.sql
##执行后输出历次所使用的xid，uba信息
--第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
--第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slot：0x1e 的wrap#从0x11d2->0x11dc，的确覆盖了10次，control scn：00ae96dc远大于 Session 2查询开始时的scn：ae931d，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scn与uba两个值作为ctl max scn、uba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scn与dba两个值作为prv tx scn、prev 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uba为8/16 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dump中uba: 0x02000010.187e.18 ctl max scn: 0x0000.00ae9095正是来自于事务开始前undo header里TRN CTL部分所包含的uba: 0x02000010.187e.18 scn: 0x0000.00ae9095，而prv tx scn：0x0000.00ae909b 和prev brb：33554460 则分别等于事务开始前slot 0x1e 所对应的scn：00ae909b和dba：0x0200001c(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xid，uba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中 Rec #0x1d、Rec #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 2的select语句执行时的snapshot scn近似等于ae931d
(2) 访问rdba：4/1779 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 0x1e的state=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 scn：ae96dc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Record是proc1.sql中第337个transaction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 scn和snapshot scn进行比较，如果snapshot scn<control 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的
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 record：8/16 Rec #0x19，说明这个undo record还在undo chain里
*-----------------------------
* 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:
/////////////
##对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:
/////////////
##在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
在session 4再次尝试覆盖的过程中，通过proc1.sql执行输出的xid，uba信息获知undo record ：8/25 Rec#0x19并没有被使用到.
##dump 所有undo块
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行
##从上面的输出可以看到8/16 Rec #0x19，8/17 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;
##在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
##在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
附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;
/
在CentOS 6.4下安装Oracle 11gR2(x64)
Oracle 11gR2 在VMWare虚拟机中安装步骤
Debian 下 安装 Oracle 11g XE R2
评论暂时关闭