【中文】 odi no.004 analysis of oracle performance degradation caused by inefficient block cleanout

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Research & Contents Team
Analysis of Oracle Performance
Degradation caused by
Inefficient block cleanout
Oracle Deep Internal report no. 004 (2016.05.20)

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Ⅰ. Transaction slot Before-image Chaining
Ⅰ-1. Questions
Ⅰ-2. Architecture of transaction slot before-image chaining
Ⅰ-3. Flow chart of delayed block cleanout
Ⅱ. Block cleanout Analysis
Ⅱ-1. Fast block cleanout (Fast commit)
Ⅱ-2. Delayed block cleanout using “commit SCN” of transaction slot
Ⅱ-3. Efficient Delayed Block Cleanout
(Delayed block cleanout using “commit SCN” of TRN CTL)
Ⅱ-4. Inefficient Delayed Block Cleanout
(Delayed block cleanout using ”commit SCN” of transaction slot before-image chaining)
Table of Agenda

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Ⅰ. Transaction slot Before-image Chaining
Oracle Deep Internal

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Ⅰ-1. Questions
进行 Select 操作时，容易发现现在使用的大容量 Oracle 数据中常常存在
owi ‘db file sequential read’。
Undo file Undo block

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把transaction slot的commit scn在data block itl的 scn/fsc column中更新
Data blockData block
“清除（Cleanout）”的意思是什么?
Question 1
BH (0x643fa1c8) file#: 5 rdba: 0x0140dcad (5/56493) class: 1 ba: 0x643b6000
st: XCURRENT md: EXCL fpin: 'kdswh11: kdst_fetch' tch: 1
Itl Xid Uba Flag Lck Scn/Fsc
0x01 0x000a.000.00000534 0x018000d2.01e6.01 C--- 0 scn 0x0000.003dbe3a
0x02 0x0007.000.000004ed 0x018000a2.01d5.01 ---- 1 fsc 0x0000.00000000
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
BH (0x643fa1c8) file#: 5 rdba: 0x0140dcad (5/56493) class: 1 ba: 0x643b6000
st: XCURRENT md: EXCL fpin: 'kdswh11: kdst_fetch' tch: 1
Itl Xid Uba Flag Lck Scn/Fsc
0x01 0x000a.000.00000534 0x018000d2.01e6.01 C--- 0 scn 0x0000.003dbe3a
0x02 0x0007.000.000004ed 0x018000a2.01d5.01 --U- 1 fsc 0x0000.003dbe4e
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
Undo Header
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------
0x00 10 0x80 0x04ed 0x0000 0x0000.003dbe4e 0x018000a2
0x01 9 0x00 0x04ec 0x0002 0x0000.003d6d72 0x00000000
0x02 9 0x00 0x04ec 0x0003 0x0000.003d6d72 0x00000000
Transaction 状态 Cleanout 状态
Answer 1
Ⅰ-1. Questions
Commit SCN
同步 Commit
SCN 前
同步 Commit
SCN 后
Transaction
状态

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瞬息间完成。
先cleanout一部分，然后以后做cleanout， 花了很短的时间。
如果 update 100亿个语句后进行commit操作，完成这100亿个
语句需要多长时间?
Question 2
Answer 2
Ⅰ-1. Questions

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Undo是有限的资源，所以Transaction slot被覆盖。为了以后的使
用, 你觉得正在等待的 commit SCN 会发生什么变化呢?
Question 3
• Undo是有限的资源, 不能永远保存。 过一段时间， undo 会变成
aging out状态。
• Undo slot的前镜像在 chaining 的过程中被储存。
• 参照后页
Answer 3
Ⅰ-1. Questions

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TRN CTL
seq: 0x0485 chd: 0x0006 ctl: 0x0005
uba: 0x0180011c.0485.31 scn: 0x0000.0022c7ff
index state cflags wrap# uel scn dba
-------------------------------------------------------------------------------
0x05 9 0x00 0x0ad4 0xffff 0x0000.0022c818 0x0180011e
0x06 9 0x00 0x0ad6 0x0005 0x0000.0022c811 0x0180011c
rdba: 0x01800160 (6/352)
TRN CTL
seq: 0x0485 chd: 0x0005 ctl: 0x0006
uba: 0x0180011e.0485.02 scn: 0x0000.0022c811
index state cflags wrap# uel scn dba
--------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e
0x06 10 0x80 0x0ad7 0xffff 0x0000.0022c821 0x0180011f
UNDO BLK
rdba: 0x0180011e seq: 0x485 Rec # 0x2 slt: 0x06 xid: 0x0001.006.00000ad7
uba: 0x0180011c.0485.31 ctl max scn: 0x0000.0022c7ff prv tx scn: 0x0000.0022c811
即将使用 chd 0x0006 slot， 所以
uba、 trn ctl SCN、 0x06 slot SCN
会以前镜像的方式储存。
Ⅰ-2. Architecture of transaction slot before image chaining (1/3)
• Chd (chain header): linked list的初始，下次
的事务即将使用的transaction table slot
• Ctl (chain tail): linked list的最后，相关undo
segment中最后使用的transaction table slot
0x06 slot 更新
(state 10, cflags 0x80, SCN 更新)
1
3
rdba: 0x0180011e (6/286)
rdba: 0x01800160 (6/352)
更新过的undo header block在
TRN CTL uba 中记录前镜像的位置，
在SCN中记录之前slot的SCN。
2
file#=6
block#=352
1 1 2
2
1

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TRN CTL
seq: 0x0485 chd: 0x0006 ctl: 0x0005
uba: 0x0180011c.0485.31 scn: 0x0000.0022c7ff
index state cflags wrap# uel scn dba
-------------------------------------------------------------------------------
0x05 9 0x00 0x0ad4 0xffff 0x0000.0022c818 0x0180011e
0x06 9 0x00 0x0ad6 0x0005 0x0000.0022c811 0x0180011c
TRN CTL
seq: 0x0485 chd: 0x0005 ctl: 0x0006
uba: 0x0180011e.0485.02 scn: 0x0000.0022c811
index state cflags wrap# uel scn dba
--------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e
0x06 9 0x00 0x0ad7 0xffff 0x0000.0022c821 0x0180011f
rdba: 0x0180011e (6/286)
UNDO BLK
rdba: 0x0180011e seq: 0x485 Rec # 0x2 slt: 0x06 xid: 0x0001.006.00000ad7
uba: 0x0180011c.0485.31 ctl max scn: 0x0000.0022c7ff prv tx scn: 0x0000.0022c811rdba: 0x0180011f (6/287)
UNDO BLK
rdba: 0x0180011f seq: 0x485 Rec # 0x2 slt: 0x05 xid: 0x0001.006.00000ad7
uba: 0x0180011e.0485.02 ctl max scn: 0x0000.0022c811 prv tx scn: 0x0000.0022c818
TRN CTL
seq: 0x0485 chd: 0x0006 ctl: 0x0005
uba: 0x0180011f.0485.02 scn: 0x0000.0022c818
index state cflags wrap# uel scn dba
--------------------------------------------------------------------------------------
0x05 10 0x80 0x0ad5 0xffff 0x0000.0022c829 0x01800120
0x06 9 0x00 0x0ad7 0x0005 0x0000.0022c821 0x0180011f
0x05 slot 更新
(state 10, cflags 0x80, SCN 更新)
Ⅰ-2. Architecture of transaction slot before image chaining (2/3)
3
rdba: 0x01800160 (6/352)
rdba: 0x01800160 (6/352)
即将使用 chd 0x0005 slot，所以
uba, trn ctl SCN, 0x05 slot SCN 会
以前镜像的方式储存。
1
rdba: 0x01800160 (6/352)
更新过的undo header block在
TRN CTL uba 中记录前镜像的位置，
在SCN中记录之前slot的SCN。
2
1 1
1
2
2

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TRN CTL
seq: 0x0485 chd: 0x0006 ctl: 0x0005
uba: 0x0180011c.0485.31 scn: 0x0000.0022c7ff
index state cflags wrap# uel scn dba
-------------------------------------------------------------------------------
0x05 9 0x00 0x0ad4 0xffff 0x0000.0022c818 0x0180011e
0x06 9 0x00 0x0ad6 0x0005 0x0000.0022c811 0x0180011c
TRN CTL
seq: 0x0485 chd: 0x0005 ctl: 0x0006
uba: 0x0180011e.0485.02 scn: 0x0000.0022c811
index state cflags wrap# uel scn dba
--------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e
0x06 9 0x00 0x0ad7 0xffff 0x0000.0022c821 0x0180011f
UNDO BLK
rdba: 0x0180011e seq: 0x485 Rec # 0x2 slt: 0x06 xid: 0x0001.006.00000ad7
uba: 0x0180011c.0485.31 ctl max scn: 0x0000.0022c7ff prv tx scn: 0x0000.0022c811
UNDO BLK
rdba: 0x0180011f seq: 0x485 Rec # 0x2 slt: 0x05 xid: 0x0001.006.00000ad7
uba: 0x0180011e.0485.02 ctl max scn: 0x0000.0022c811 prv tx scn: 0x0000.0022c818
TRN CTL
seq: 0x0485 chd: 0x0006 ctl: 0x0005
uba: 0x0180011f.0485.02 scn: 0x0000.0022c818
index state cflags wrap# uel scn dba
--------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad5 0xffff 0x0000.0022c829 0x01800120
0x06 9 0x00 0x0ad7 0x0005 0x0000.0022c821 0x0180011f
TRN CTL
seq: 0x0486 chd: 0x0005 ctl: 0x0006
uba: 0x01800120.0486.02 scn: 0x0000.0022c821
index state cflags wrap# uel scn dba
--------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120
0x06 10 0x80 0x0ad8 0xffff 0x0000.0022c832 0x01800121
UNDO BLK
rdba: 0x01800120 seq: 0x486 Rec # 0x2 slt: 0x06 xid: 0x0001.005.00000ad5
uba: 0x0180011f.0485.02 ctl max scn: 0x0000.0022c818 prv tx scn: 0x0000.0022c821
0x06 slot 更新
(state 10, cflags 0x80, SCN 更新)
Ⅰ-2. Architecture of transaction slot before image chaining (3/3)
3
Endless loop..
rdba: 0x01800160 (6/352)
rdba: 0x01800160 (6/352)
rdba: 0x01800160 (6/352)
rdba: 0x01800160 (6/352)
rdba: 0x0180011e (6/286)
rdba: 0x0180011f (6/287)
rdba: 0x01800120 (6/288)
即将使用 chd 0x0006 slot， 所以
uba、 trn ctl SCN、 0x06 slot SCN
会以前镜像的方式储存。
更新过的undo header block在
TRN CTL uba 中记录前镜像的位置，
在SCN中记录之前slot的SCN。
1
2
1 1
1
2
2

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是
不
不
是
是
不
Wrap number
一样吗?
前镜像 SCN 比
Query SCN 更高吗?
同步 TRN CTL SCN
重复进行跟前镜像的比较
同步相关 SCN
同步相关 SCN
<延迟块清除的处理过程>
高效的延迟块清除
低效的延迟块清除
delayed block cleanout
using “commit SCN” of transaction slot
Ⅰ-3. Flow chart of delayed block cleanout
Query SCN 比 TRN
CTL SCN更高吗?

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Ⅰ-3. Flow chart of delayed block cleanout
<低效的延迟块清除> Undo Header
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x01800120.0486.02 scn: 0x0000.0022d821
index state cflags wrap# uel scn dba
---------------------------------------------------------------------------------------
--
0x05 9 0x00 0x0ad5 0x0006 0x0000.0022d829 0x01800120
0x06 9 0x00 0x0ad8 0xffff 0x0000.0022d832 0x01800121
Undo Block
buffer tsn: 6 rdba: 0x01800120 (6/288)
UNDO BLK:
xid: 0x0001.005.00000ad5 seq: 0x486 cnt: 0x1 irb: 0x1 icl: 0x0 flg:
0x0000
* Rec #0x2 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc:
5(0x00000005)
*-----------------------------
uba: 0x0180011f.0485.02 ctl max scn: 0x0000.0022d818 prv tx scn:
0x0000.0022d821
txn start scn: scn: 0x0000.0022d831 logon user: 5
prev brb: 25166111 prev bcl: 0
Undo Block
buffer tsn: 6 rdba: 0x0180011f (6/287)
UNDO BLK:
xid: 0x0001.006.00000ad7 seq: 0x485 cnt: 0x1 irb: 0x1 icl: 0x0 flg:
0x0000
* Rec #0x2 slt: 0x05 objn: 70146(0x00011202) objd: 70146 tblspc:
5(0x00000005)
*-----------------------------
uba: 0x0180011e.0485.02 ctl max scn: 0x0000.0022d811 prv tx scn:
0x0000.0022d818
txn start scn: scn: 0x0000.0022d828 logon user: 5
prev brb: 25166110 prev bcl: 0
1
2
3
4
Wrap number
比较
把 TRN CTL SCN 跟
Query SCN 比较
把前镜像 SCN 跟
Query SCN 比较
同步相关前镜像 SCN
NO
NO
NO
Wrap number
一样吗?
Query SCN 比 TRN
CTL SCN更高吗?
前镜像 SCN 比
Query SCN 更高吗?
同步相关 SCN
0x0ad6 ≠0x0ad8
• Query SCN: 0x0000.0022d811
• Wrap#: 0x0ad6 (itl의 xid)
1
2
3
4
d811 < d821
Query SCN TRN CTL SCN
d811 < d818
Query SCN TRN CTL SCN
d811 ≥ d811
Query SCN TRN CTL SCN

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Oracle Deep Internal
Ⅱ. Block cleanout Analysis

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Ⅱ-1. Fast block cleanout (Fast commit)
Oracle Deep Internal

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Commit SCN
↓
9 (Committed)
10 (Active)
0x01 0x0008.013.
000018a8
1--U- Commit SCN
(Base#)
0x13 0x008004f8
0x008004f8.
00cf.06
如果当事务修改数据块的数据量没有超过
Buffer Cache的10%的话，会在会话内存
中生成新列表。
Fast block cleanout
“ ”
0x18a8
Ⅱ-1. Fast block cleanout (Fast commit)

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Oracle Deep Internal
Ⅱ-2. Delayed block cleanout
using “commit SCN” of Transaction slot

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Ⅱ-2. Delayed block cleanout using “commit SCN” of transaction slot
Delayed block cleanout
“在commit的时候，没被清除的块（当修改的数据块的数据量超过 buffer cache 的10%）、
在内存上经过 flush 而没有被清除,并且记录在 datafile上的块会在下一次会话时被清除。”
0x13 0x0080006c
0x01 0C--- Commit SCN0x008004f8
00cf.06
9 (Committed) Commit SCN0x18a8
0x0008.013.
000018a8
Row Lock
执行delayed block cleanout的会话使用没有cleanout的事务的xid，确认undo header
block的transaction table（transaction是否完成，SCN）之后，在相关block header的
ITL中进行Lock byte解除, SCN设定，将Flag设定为C---。随后生成相关的redo log。

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Ⅱ-3. Efficient Delayed Block Cleanout
Oracle Deep Internal

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* Upper bound commit
Upper bound commit 就是…
“一般来说，Oracle系统会使用当下的 commit SCN，但如果发生了overwrite的话，
则为从产生 commit 的时间(811)开始,一直到即将清除的 query SCN(818)的这段时间里的最大值。
Upper bound commit

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Ⅱ-3. Efficient Delayed Block Cleanout
Update Table T1
Flush Buffer
Commit
Update & Commit
Update & Commit
Update & Commit
Update & Commit
Select Table T1
t1
t2
t3
S1 S2Time
• 让 10个 Undo segments 中 9个处于 offline状态，一个处于 online 状态。
• 让 34个 Undo segments 中 32个处于 active状态，仅仅使用两个。
测试

22. SGA
Undo SegmentData Block
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Rows
1. 初始状态
ITL
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Header
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c
Undo Block
Itl Xid Uba Flag Lck Scn/fsc
ASCII code 41
=> Value ‘A’

23. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
Rows
ITL
2. update t1 set col2='B';
Undo Header
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c
Itl Xid Uba Flag Lck Scn/fsc
ASCII code 41
=> Value ‘A’
ㅁ
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c
Undo Block
buffer tsn: 6 rdba: 0x0180011b (6/283)
UNDO BLK:
xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000
* Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3
txn start scn: scn: 0x0000.006e8efa logon user: 5
prev brb: 25166108 prev bcl: 0
将 undo 段头块
上传至内存

24. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
Rows
ITL
2. update t1 set col2='B';
Undo Header
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c
Itl Xid Uba Flag Lck Scn/fsc
ASCII code 41
=> Value ‘A’
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c
Undo Block
buffer tsn: 6 rdba: 0x0180011b (6/283)
UNDO BLK:
xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000
* Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3
txn start scn: scn: 0x0000.006e8efa logon user: 5
prev brb: 25166108 prev bcl: 0
即将使用 chd 0x0014 slot，所以
uba、 trn ctl SCN、 0x14 slot SCN
会以前镜像方式储存。

25. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
Rows
ITL
Undo Block
buffer tsn: 6 rdba: 0x0180011b (6/283)
UNDO BLK:
xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000
* Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3
txn start scn: scn: 0x0000.006e8efa logon user: 5
prev brb: 25166108 prev bcl: 0
2. update t1 set col2='B';
Undo Header
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c
Itl Xid Uba Flag Lck Scn/fsc
ASCII code 41
=> Value ‘A’
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c
BH (0x63fe3de8) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63d6e000
st: XCURRENT md: NULL tch: 1
buffer tsn: 6 rdba: 0x01800120 (6/288)
…
TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b
更新过的undo header block在TRN CTL
uba 中记录前镜像的位置，在SCN中记录
之前slot的SCN。
有前镜像的
Undo block 位置
0x14 slot 更新
(state, cflag, wrap#, scn)

26. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
Rows
ITL
Undo Block
buffer tsn: 6 rdba: 0x0180011b (6/283)
UNDO BLK:
xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000
* Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3
txn start scn: scn: 0x0000.006e8efa logon user: 5
prev brb: 25166108 prev bcl: 0
BH (0x63fe3de8) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63d6e000
st: XCURRENT md: NULL tch: 1
buffer tsn: 6 rdba: 0x01800120 (6/288)
…
TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b
2. update t1 set col2='B';
Undo Header
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c
Itl Xid Uba Flag Lck Scn/fsc
ASCII code 41
=> Value ‘A’
Rows
ITL
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Itl Xid Uba Flag Lck Scn/fscItl Xid Uba Flag Lck Scn/fsc

27. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
Rows
ITL
Undo Block
buffer tsn: 6 rdba: 0x0180011b (6/283)
UNDO BLK:
xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000
* Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3
txn start scn: scn: 0x0000.006e8efa logon user: 5
prev brb: 25166108 prev bcl: 0
BH (0x63fe3de8) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63d6e000
st: XCURRENT md: NULL tch: 1
buffer tsn: 6 rdba: 0x01800120 (6/288)
…
TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b
2. update t1 set col2='B';
Undo Header
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0004 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.1cc1.05 scn: 0x0000.006e8ee1
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 9 0x00 0x353a 0x0004 0x0000.006e8ee3 0x0180011c
Itl Xid Uba Flag Lck Scn/fsc
ASCII code 41
=> Value ‘A’
Rows
ITL
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Itl Xid Uba Flag Lck Scn/fsc
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Itl Xid Uba Flag Lck Scn/fsc
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ASCII code 42
=> Value ‘B’

28. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
3. alter system flush buffer_cache ;
Undo Header
Undo Block
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b
buffer tsn: 6 rdba: 0x0180011b (6/283)
UNDO BLK:
xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000
* Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3
txn start scn: scn: 0x0000.006e8efa logon user: 5
prev brb: 25166108 prev bcl: 0
flush
Itl Xid Uba Flag Lck Scn/fsc

29. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
4. commit;
BH (0x637f5020) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63730000
st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 1
buffer tsn: 6 rdba: 0x01800120 (6/288)
…
TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0014 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0x0014 0x0000.006e8ee4 0x0180011b
0x14 9 0x00 0x353b 0xffff 0x0000.006e8efd 0x0180011b
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Header
Undo Block
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b
buffer tsn: 6 rdba: 0x0180011b (6/283)
UNDO BLK:
xid: 0x0006.014.0000353b seq: 0x1cc1 cnt: 0x31 irb: 0x31 icl: 0x0 flg: 0x0000
* Rec #0xa slt: 0x14 objn: 78003(0x000130b3) objd: 78003 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011c.1cc1.05 ctl max scn: 0x0000.006e8ee1 prv tx scn: 0x0000.006e8ee3
txn start scn: scn: 0x0000.006e8efa logon user: 5
prev brb: 25166108 prev bcl: 0
Itl Xid Uba Flag Lck Scn/fsc

30. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
5.
Undo Block
Undo Header
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
BH (0x637f5020) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63730000
st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 2
buffer tsn: 6 rdba: 0x01800120 (6/288)
…
TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0014 inc: 0x00000000 nfb: 0x0000
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011b.1cc1.32 scn: 0x0000.006e8ee4
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 10 0x80 0x3539 0x0005 0x0000.006e8f05 0x0180011d
0x14 9 0x00 0x353b 0xffff 0x0000.006e8efd 0x0180011b
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b
buffer tsn: 6 rdba: 0x0180011d (6/285)
UNDO BLK:
xid: 0x0006.004.00003539 seq: 0x1cc1 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000
* Rec #0x1 slt: 0x04 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005)
col 1: [2000]
41 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
Itl Xid Uba Flag Lck Scn/fsc
Session2> Update t2 set col2=‘B’;
Session2> Commit;

31. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
6.
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
Undo Header
BH (0x637f5020) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63730000
st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 2
buffer tsn: 6 rdba: 0x01800120 (6/288)
…
TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011d.1cc1.02 scn: 0x0000.006e8efd
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3539 0xffff 0x0000.006e8f06 0x0180011d
0x14 10 0x80 0x353c 0x0005 0x0000.006e8f0d 0x0180011e
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b
buffer tsn: 6 rdba: 0x0180011e (6/286)
UNDO BLK:
xid: 0x0006.014.0000353c seq: 0x1cc1 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000
* Rec #0x1 slt: 0x14 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005)
col 1: [2000]
50 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
Itl Xid Uba Flag Lck Scn/fsc
Session2> Update t2 set col2=‘B’;
Session2> Commit;

32. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
7.
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
Undo Header
BH (0x637f5020) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63730000
st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 2
buffer tsn: 6 rdba: 0x01800120 (6/288)
…
TRN CTL:: seq: 0x1cc1 chd: 0x0014 ctl: 0x0014 inc: 0x00000000 nfb: 0x0000
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011e.1cc1.02 scn: 0x0000.006e8f06
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 10 0x80 0x353a 0x0005 0x0000.006e8f15 0x0180011f
0x14 9 0x00 0x353c 0xffff 0x0000.006e8f0e 0x0180011e
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b
buffer tsn: 6 rdba: 0x0180011f (6/287)
UNDO BLK:
xid: 0x0006.004.0000353a seq: 0x1cc1 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000
* Rec #0x1 slt: 0x04 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005)
col 1: [2000]
51 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
Itl Xid Uba Flag Lck Scn/fsc
Session2> Update t2 set col2=‘B’;
Session2> Commit;

33. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
8.
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
Undo Header
BH (0x637f5020) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x63730000
st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 3
buffer tsn: 6 rdba: 0x01800120 (6/288)
…
TRN CTL:: seq: 0x1cc2 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011f.1cc1.02 scn: 0x0000.006e8f0e
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x353a 0xffff 0x0000.006e8f16 0x0180011f
0x14 10 0x80 0x353d 0x0005 0x0000.006e8f1c 0x01800130
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc1 chd: 0x0004 ctl: 0x0004 inc: 0x00000000 nfb: 0x0000
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011b.1cc1.0a scn: 0x0000.006e8ee3
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x3538 0xffff 0x0000.006e8ee4 0x0180011b
0x14 10 0x80 0x353b 0x0005 0x0000.006e8efa 0x0180011b
buffer tsn: 6 rdba: 0x01800130 (6/304)
UNDO BLK:
xid: 0x0006.014.0000353d seq: 0x1cc2 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000
* Rec #0x1 slt: 0x14 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005)
col 1: [2000]
52 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
Itl Xid Uba Flag Lck Scn/fsc
Session2> Update t2 set col2=‘B’;
Session2> Commit;

34. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
BH (0x647efe78) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x646aa000
st: XCURRENT md: NULL fpin: 'ktuwh05: ktugct' tch: 1
buffer tsn: 6 rdba: 0x01800120 (6/288)
…
TRN CTL:: seq: 0x1cc2 chd: 0x0004 ctl: 0x0014 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011f.1cc1.02 scn: 0x0000.006e8f0e
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x353a 0x0014 0x0000.006e8f16 0x0180011f
0x14 9 0x00 0x353d 0xffff 0x0000.006e8f1e 0x01800130
9. select /*+ full(t1) */count(*) from t1 where rownum <= 1;
BH (0x657f85c0) file#: 5 rdba: 0x01418413 (5/99347) class: 1 ba: 0x65788000
st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1
buffer tsn: 5 rdba: 0x01418413 (5/99347)
…
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 C-U- 0 scn 0x0000.006e8f0e
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
…
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
Undo Header
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc2 chd: 0x0004 ctl: 0x0014 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011f.1cc1.02 scn: 0x0000.006e8f0e
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x353a 0x0014 0x0000.006e8f16 0x0180011f
0x14 9 0x00 0x353d 0xffff 0x0000.006e8f1e 0x01800130
buffer tsn: 6 rdba: 0x01800130 (6/304)
UNDO BLK:
xid: 0x0006.014.0000353d seq: 0x1cc2 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000
* Rec #0x1 slt: 0x14 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005)
col 1: [2000]
52 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
Itl Xid Uba Flag Lck Scn/fsc
Itl Xid Uba Flag Lck Scn/fsc
ASCII code 42
=> Value ‘B’
Begin cleaning out block ...
Block header dump: 0x01418413
…
Itl Xid Uba Flag Lck Scn/Fsc
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
WAIT #139971596639184: nam='db file sequential read' ela= 15 file#=6 block#=288 blocks=1 obj#=0 tim=1460423039184663
…
Block cleanout record, scn: 0xffff.ffffffff ver: 0x01 opt: 0x01, entries follow...
itli: 2 flg: 1 scn: 0x0000.006e8f0e
Block header dump: 0x01418413
…
Itl Xid Uba Flag Lck Scn/Fsc
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 C-U- 0 scn 0x0000.006e8f0e
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo header Block

35. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
BH (0x647efe78) file#: 6 rdba: 0x01800120 (6/288) class: 27 ba: 0x646aa000
st: XCURRENT md: NULL fpin: 'ktuwh05: ktugct' tch: 1
buffer tsn: 6 rdba: 0x01800120 (6/288)
…
TRN CTL:: seq: 0x1cc2 chd: 0x0004 ctl: 0x0014 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011f.1cc1.02 scn: 0x0000.006e8f0e
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x353a 0x0014 0x0000.006e8f16 0x0180011f
0x14 9 0x00 0x353d 0xffff 0x0000.006e8f1e 0x01800130
9. select /*+ full(t1) */count(*) from t1 where rownum <= 1;
BH (0x657f85c0) file#: 5 rdba: 0x01418413 (5/99347) class: 1 ba: 0x65788000
st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1
buffer tsn: 5 rdba: 0x01418413 (5/99347)
…
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 C-U- 0 scn 0x0000.006e8f0e
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
…
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x002c.002.000000b4 0x00000000.0000.00 C--- 0 scn 0x0000.006e8426
0x02 0x0006.014.0000353b 0x0180011b.1cc1.28 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
Undo Header
buffer tsn: 6 rdba: 0x01800120 (6/288)
TRN CTL:: seq: 0x1cc2 chd: 0x0004 ctl: 0x0014 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011f.1cc1.02 scn: 0x0000.006e8f0e
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x04 9 0x00 0x353a 0x0014 0x0000.006e8f16 0x0180011f
0x14 9 0x00 0x353d 0xffff 0x0000.006e8f1e 0x01800130
buffer tsn: 6 rdba: 0x01800130 (6/304)
UNDO BLK:
xid: 0x0006.014.0000353d seq: 0x1cc2 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000
* Rec #0x1 slt: 0x14 objn: 78004(0x000130b4) objd: 78004 tblspc: 5(0x00000005)
col 1: [2000]
52 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
Itl Xid Uba Flag Lck Scn/fsc
Itl Xid Uba Flag Lck Scn/fsc
ASCII code 42
=> Value ‘B’

36. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
Ⅱ-4. Inefficient Delayed Block Cleanout.
Oracle Deep Internal

37. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
Ⅱ-4. Inefficient Delayed Block Cleanout
• 让 10个 Undo segments 中 9个处于 offline状态，一个处于 online 状态。
• 让 34个 Undo segments 中 32个处于 active状态，仅仅使用两个。
测试
Update Table T1
Flush Buffer
Commit
Select Table T1
t1
t2
t4
S1 S2Time
t3
Update & Commit
Update & Commit
Update & Commit
Update & Commit
Set transaction
read only

38. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
1.
ITL
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Header
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c
ASCII code 41
=> Value ‘A’
Undo Block
Itl Xid Uba Flag Lck Scn/fsc
初始状态

39. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
将 undo 段头块
上传至内存
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
ITL
ASCII code 41
=> Value ‘A’
0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
buffer tsn: 6 rdba: 0x0180011c (6/284)
UNDO BLK:
xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000
* Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005)
uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe
txn start scn: scn: 0x0000.0022c809 logon user: 5
prev brb: 25166108 prev bcl: 0
2. update t1 set col2='B';
Undo Header
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c
Itl Xid Uba Flag Lck Scn/fsc
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c

40. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
ITL
ASCII code 41
=> Value ‘A’
0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
buffer tsn: 6 rdba: 0x0180011c (6/284)
UNDO BLK:
xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000
* Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005)
uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe
txn start scn: scn: 0x0000.0022c809 logon user: 5
prev brb: 25166108 prev bcl: 0
2. update t1 set col2='B';
Undo Header
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c
Itl Xid Uba Flag Lck Scn/fsc
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c
即将使用 chd 0x0006 slot， 所以
uba、 trn ctl SCN、 0x06 slot
SCN会以前镜像的方式储存。

41. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
ITL
ASCII code 41
=> Value ‘A’
0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
buffer tsn: 6 rdba: 0x0180011c (6/284)
UNDO BLK:
xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000
* Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe
txn start scn: scn: 0x0000.0022c809 logon user: 5
prev brb: 25166108 prev bcl: 0
2. update t1 set col2='B';
Undo Header
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c
Itl Xid Uba Flag Lck Scn/fsc
BH (0x663ea0a0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x66210000
st: XCURRENT md: NULL tch: 1
buffer tsn: 6 rdba: 0x01800160 (6/352)
…
TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c
有前镜像的
Undo block 位置
更新过的undo header block在TRN CTL
uba 中记录前镜像的位置，在SCN中记录
之前slot的SCN。
0x06 slot 更新
(state, cflag, wrap#, scn)

42. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
ITL
ASCII code 41
=> Value ‘A’
0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
buffer tsn: 6 rdba: 0x0180011c (6/284)
UNDO BLK:
xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000
* Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe
txn start scn: scn: 0x0000.0022c809 logon user: 5
prev brb: 25166108 prev bcl: 0
2. update t1 set col2='B';
Undo Header
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c
Itl Xid Uba Flag Lck Scn/fsc
BH (0x663ea0a0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x66210000
st: XCURRENT md: NULL tch: 1
buffer tsn: 6 rdba: 0x01800160 (6/352)
…
TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
ITL
0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Itl Xid Uba Flag Lck Scn/fsc

43. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
ITL
ASCII code 41
=> Value ‘A’
0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
buffer tsn: 6 rdba: 0x0180011c (6/284)
UNDO BLK:
xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000
* Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe
txn start scn: scn: 0x0000.0022c809 logon user: 5
prev brb: 25166108 prev bcl: 0
2. update t1 set col2='B';
Undo Header
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.05 scn: 0x0000.0022c7fb
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 9 0x00 0x0ad5 0x0005 0x0000.0022c7fe 0x0180011c
Itl Xid Uba Flag Lck Scn/fsc
BH (0x663ea0a0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x66210000
st: XCURRENT md: NULL tch: 1
buffer tsn: 6 rdba: 0x01800160 (6/352)
…
TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 41
ITL
0x01 0x001e.01b.0000000d 0x00000000.0000.00 C--- 0 scn 0x0000.002263d9
0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Itl Xid Uba Flag Lck Scn/fsc
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Itl Xid Uba Flag Lck Scn/fsc
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ASCII code 42
=> Value ‘B’

44. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
3. alter system flush buffer_cache ;
Undo Header
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c
Undo Block
buffer tsn: 6 rdba: 0x0180011c (6/284)
UNDO BLK:
xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000
* Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe
txn start scn: scn: 0x0000.0022c809 logon user: 5
prev brb: 25166108 prev bcl: 0
flush
Itl Xid Uba Flag Lck Scn/fsc

45. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
4. commit;
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Header
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c
BH (0x66be9f68) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x66a0e000
st: XCURRENT md: NULL fpin: 'ktuwh61: ktugus:ktucmt' tch: 1
buffer tsn: 6 rdba: 0x01800160 (6/352)
…
TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0x0006 0x0000.0022c7ff 0x0180011d
0x06 9 0x00 0x0ad6 0xffff 0x0000.0022c811 0x0180011c
Undo Block
buffer tsn: 6 rdba: 0x0180011c (6/284)
UNDO BLK:
xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000
* Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe
txn start scn: scn: 0x0000.0022c809 logon user: 5
prev brb: 25166108 prev bcl: 0
Itl Xid Uba Flag Lck Scn/fsc

46. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
5. Set transaction read only ;
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Header
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0005 inc: 0x00000000 nfb: 0x0001
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.09 scn: 0x0000.0022c7fe
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad3 0xffff 0x0000.0022c7ff 0x0180011d
0x06 10 0x80 0x0ad6 0x0005 0x0000.0022c809 0x0180011c
Undo Block
buffer tsn: 6 rdba: 0x0180011c (6/284)
UNDO BLK:
xid: 0x0001.006.00000ad6 seq: 0x485 cnt: 0x30 irb: 0x30 icl: 0x0 flg: 0x0000
* Rec #0x9 slt: 0x06 objn: 70145(0x00011201) objd: 70145 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011c.0485.05 ctl max scn: 0x0000.0022c7fb prv tx scn: 0x0000.0022c7fe
txn start scn: scn: 0x0000.0022c809 logon user: 5
prev brb: 25166108 prev bcl: 0
Itl Xid Uba Flag Lck Scn/fsc
<Read only >
• Commit (0x0000.0022c811)
• Commit (0x0000.0022c818)

47. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
6.
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
Undo Header
Itl Xid Uba Flag Lck Scn/fsc
ASCII code 42
=> Value ‘B’
Session2> Update t2 set col2=‘B’;
Session2> Commit;
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011c.0485.31 scn: 0x0000.0022c7ff
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad4 0xffff 0x0000.0022c818 0x0180011e
0x06 9 0x00 0x0ad6 0x0005 0x0000.0022c811 0x0180011c
buffer tsn: 6 rdba: 0x0180011c (6/284)
UNDO BLK:
xid: 0x0001.005.00000ad4 seq: 0x485 cnt: 0x32 irb: 0x32 icl: 0x0 flg: 0x0000
* Rec #0x31 slt: 0x05 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011c.0485.09 ctl max scn: 0x0000.0022c7fe prv tx scn: 0x0000.0022c7ff
txn start scn: scn: 0x0000.0022c816 logon user: 5
prev brb: 25166109 prev bcl: 0

48. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
7.
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
Undo Header
Itl Xid Uba Flag Lck Scn/fsc
ASCII code 42
=> Value ‘B’
Session2> Update t2 set col2=‘B’;
Session2> Commit;
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0485 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011e.0485.02 scn: 0x0000.0022c811
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e
0x06 9 0x00 0x0ad7 0xffff 0x0000.0022c821 0x0180011f
buffer tsn: 6 rdba: 0x0180011e (6/286)
UNDO BLK:
xid: 0x0001.006.00000ad7 seq: 0x485 cnt: 0x3 irb: 0x3 icl: 0x0 flg: 0x0000
* Rec #0x2 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011c.0485.31 ctl max scn: 0x0000.0022c7ff prv tx scn: 0x0000.0022c811
txn start scn: scn: 0x0000.0022c820 logon user: 5
prev brb: 25166108 prev bcl: 0

49. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
8.
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
Undo Header
Itl Xid Uba Flag Lck Scn/fsc
Session2> Update t2 set col2=‘B’;
Session2> Commit;
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0486 chd: 0x0006 ctl: 0x0005 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011f.0485.02 scn: 0x0000.0022c818
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad5 0xffff 0x0000.0022c829 0x01800120
0x06 9 0x00 0x0ad7 0x0005 0x0000.0022c821 0x0180011f
buffer tsn: 6 rdba: 0x0180011f (6/287)
UNDO BLK:
xid: 0x0001.006.00000ad7 seq: 0x485 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000
* Rec #0x2 slt: 0x05 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011e.0485.02 ctl max scn: 0x0000.0022c811 prv tx scn: 0x0000.0022c818
txn start scn: scn: 0x0000.0022c828 logon user: 5
prev brb: 25166110 prev bcl: 0

50. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
9.
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
Undo Header
Itl Xid Uba Flag Lck Scn/fsc
Session2> Update t2 set col2=‘B’;
Session2> Commit;
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x01800120.0486.02 scn: 0x0000.0022c821
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120
0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121
buffer tsn: 6 rdba: 0x01800120 (6/288)
UNDO BLK:
xid: 0x0001.005.00000ad5 seq: 0x486 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000
* Rec #0x2 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011f.0485.02 ctl max scn: 0x0000.0022c818 prv tx scn: 0x0000.0022c821
txn start scn: scn: 0x0000.0022c831 logon user: 5
prev brb: 25166111 prev bcl: 0

51. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
BH (0x623e85d0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x621e4000
st: XCURRENT md: NULL fpin: 'ktuwh05: ktugct' tch: 0
buffer tsn: 6 rdba: 0x01800160 (6/352)
…
TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x01800120.0486.02 scn: 0x0000.0022c821
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------
0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120
0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121
10. select /*+ full(t1) */count(*) from t1 where rownum <= 1;
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
buffer tsn: 6 rdba: 0x01800121 (6/289)
UNDO BLK:
xid: 0x0001.006.00000ad8 seq: 0x486 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000
* Rec #0x1 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005)
Undo Header
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x01800120.0486.02 scn: 0x0000.0022c821
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120
0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121
BH (0x66bf7720) file#: 5 rdba: 0x014000e3 (5/227) class: 1 ba: 0x66b70000
st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1
buffer tsn: 5 rdba: 0x014000e3 (5/227)
…
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
…
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
Itl Xid Uba Flag Lck Scn/fsc
Itl Xid Uba Flag Lck Scn/fsc
Begin cleaning out block ...
Block header dump: 0x014000e3
…
Itl Xid Uba Flag Lck Scn/fsc
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
WAIT #140004262172792: nam='db file sequential read' ela= 9 file#=6 block#=352 blocks=1 obj#=0 tim=1459261058673224
WAIT #140004262172792: nam='db file sequential read' ela= 13 file#=6 block#=288 blocks=1 obj#=0 tim=1459261058676417
WAIT #140004262172792: nam='db file sequential read' ela= 10 file#=6 block#=287 blocks=1 obj#=0 tim=1459261058677687
…
Block cleanout record, scn: 0x0000.0022c834 ver: 0x01 opt: 0x01, entries follow...
itli: 2 flg: 1 scn: 0x0000.0022c811
Block header dump: 0x014000e3
…
Itl Xid Uba Flag Lck Scn/fsc
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undoheader Block
第二次 update Undo Block
第一次 update Undo Block
BH (0x673f4b40) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x67328000
st: CR md: NULL tch: 1
buffer tsn: 6 rdba: 0x01800160 (6/352)
…
TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011e.0485.02 scn: 0x0000.0022c811
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e
0x06 9 0x00 0x0ad7 0xffff 0x0000.0022c821 0x0180011f
Begin cleaning out block ...
Block header dump: 0x014000e3
…
Itl Xid Uba Flag Lck Scn/fsc
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
WAIT #140004262172792: nam='db file sequential read' ela= 9 file#=6 block#=352 blocks=1 obj#=0 tim=1459261058673224
WAIT #140004262172792: nam='db file sequential read' ela= 13 file#=6 block#=288 blocks=1 obj#=0 tim=1459261058676417
WAIT #140004262172792: nam='db file sequential read' ela= 10 file#=6 block#=287 blocks=1 obj#=0 tim=1459261058677687
…
Block cleanout record, scn: 0x0000.0022c834 ver: 0x01 opt: 0x01, entries follow...
itli: 2 flg: 1 scn: 0x0000.0022c811
Block header dump: 0x014000e3
…
Itl Xid Uba Flag Lck Scn/fsc
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo header Block
第二次 update Undo Block
第一次 update Undo Block

52. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
BH (0x623e85d0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x621e4000
st: XCURRENT md: NULL fpin: 'ktuwh05: ktugct' tch: 0
buffer tsn: 6 rdba: 0x01800160 (6/352)
…
TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x01800120.0486.02 scn: 0x0000.0022c821
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------
0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120
0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121
10. select /*+ full(t1) */count(*) from t1 where rownum <= 1;
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
Undo Header
BH (0x66bf7720) file#: 5 rdba: 0x014000e3 (5/227) class: 1 ba: 0x66b70000
st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1
buffer tsn: 5 rdba: 0x014000e3 (5/227)
…
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
…
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
Itl Xid Uba Flag Lck Scn/fsc
Itl Xid Uba Flag Lck Scn/fsc
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x01800120.0486.02 scn: 0x0000.0022c821
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120
0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121
buffer tsn: 6 rdba: 0x01800120 (6/288)
UNDO BLK:
xid: 0x0001.005.00000ad5 seq: 0x486 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000
* Rec #0x2 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011f.0485.02 ctl max scn: 0x0000.0022c818 prv tx scn: 0x0000.0022c821
txn start scn: scn: 0x0000.0022c831 logon user: 5
prev brb: 25166111 prev bcl: 0
Begin cleaning out block ...
Block header dump: 0x014000e3
…
Itl Xid Uba Flag Lck Scn/fsc
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
WAIT #140004262172792: nam='db file sequential read' ela= 9 file#=6 block#=352 blocks=1 obj#=0 tim=1459261058673224
WAIT #140004262172792: nam='db file sequential read' ela= 13 file#=6 block#=288 blocks=1 obj#=0 tim=1459261058676417
WAIT #140004262172792: nam='db file sequential read' ela= 10 file#=6 block#=287 blocks=1 obj#=0 tim=1459261058677687
…
Block cleanout record, scn: 0x0000.0022c834 ver: 0x01 opt: 0x01, entries follow...
itli: 2 flg: 1 scn: 0x0000.0022c811
Block header dump: 0x014000e3
…
Itl Xid Uba Flag Lck Scn/fsc
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo header Block
第二次 update Undo Block
第一次 update Undo Block
Scn: 0x0000.0022c821
Scn: 0x0000.0022c818
Scn: 0x0000.0022c811

53. SGA
Undo SegmentData Block
© Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
BH (0x623e85d0) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x621e4000
st: XCURRENT md: NULL fpin: 'ktuwh05: ktugct' tch: 0
buffer tsn: 6 rdba: 0x01800160 (6/352)
…
TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x01800120.0486.02 scn: 0x0000.0022c821
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------
0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120
0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121
10. select /*+ full(t1) */count(*) from t1 where rownum <= 1;
Rows
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x2 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
ITL
ASCII code 42
=> Value ‘B’
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo Block
Undo Header
BH (0x66bf7720) file#: 5 rdba: 0x014000e3 (5/227) class: 1 ba: 0x66b70000
st: XCURRENT md: NULL fpin: 'kdswh11: kdst_fetch' tch: 1
buffer tsn: 5 rdba: 0x014000e3 (5/227)
…
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
…
block_row_dump:
tab 0, row 0, @0x1f70
tl: 16 fb: --H-FL-- lb: 0x0 cc: 2
col 0: [10] 31 20 20 20 20 20 20 20 20 20
col 1: [ 1] 42
Itl Xid Uba Flag Lck Scn/fsc
Itl Xid Uba Flag Lck Scn/fsc
buffer tsn: 6 rdba: 0x01800160 (6/352)
TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x01800120.0486.02 scn: 0x0000.0022c821
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad5 0x0006 0x0000.0022c829 0x01800120
0x06 9 0x00 0x0ad8 0xffff 0x0000.0022c832 0x01800121
buffer tsn: 6 rdba: 0x01800120 (6/288)
UNDO BLK:
xid: 0x0001.005.00000ad5 seq: 0x486 cnt: 0x1 irb: 0x1 icl: 0x0 flg: 0x0000
* Rec #0x2 slt: 0x06 objn: 70146(0x00011202) objd: 70146 tblspc: 5(0x00000005)
*-----------------------------
uba: 0x0180011f.0485.02 ctl max scn: 0x0000.0022c818 prv tx scn: 0x0000.0022c821
txn start scn: scn: 0x0000.0022c831 logon user: 5
prev brb: 25166111 prev bcl: 0
Begin cleaning out block ...
Block header dump: 0x014000e3
…
Itl Xid Uba Flag Lck Scn/fsc
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 ---- 3 fsc 0x0000.00000000
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
WAIT #140004262172792: nam='db file sequential read' ela= 9 file#=6 block#=352 blocks=1 obj#=0 tim=1459261058673224
WAIT #140004262172792: nam='db file sequential read' ela= 13 file#=6 block#=288 blocks=1 obj#=0 tim=1459261058676417
WAIT #140004262172792: nam='db file sequential read' ela= 10 file#=6 block#=287 blocks=1 obj#=0 tim=1459261058677687
…
Block cleanout record, scn: 0x0000.0022c834 ver: 0x01 opt: 0x01, entries follow...
itli: 2 flg: 1 scn: 0x0000.0022c811
Block header dump: 0x014000e3
…
Itl Xid Uba Flag Lck Scn/fsc
0x01 0x001c.005.00000010 0x00000000.0000.00 C--- 0 scn 0x0000.0022bf23
0x02 0x0001.006.00000ad6 0x0180011c.0485.27 C-U- 0 scn 0x0000.0022c811
0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000
Undo header Block
第二次 update Undo Block
第一次 update Undo Block
BH (0x673f4b40) file#: 6 rdba: 0x01800160 (6/352) class: 17 ba: 0x67328000
st: CR md: NULL tch: 1
buffer tsn: 6 rdba: 0x01800160 (6/352)
…
TRN CTL:: seq: 0x0486 chd: 0x0005 ctl: 0x0006 inc: 0x00000000 nfb: 0x0002
mgc: 0xb000 xts: 0x0068 flg: 0x0001 opt: 2147483646 (0x7ffffffe)
uba: 0x0180011e.0485.02 scn: 0x0000.0022c811
…
index state cflags wrap# uel scn dba
-----------------------------------------------------------------------------------------
0x05 9 0x00 0x0ad4 0x0006 0x0000.0022c818 0x0180011e
0x06 9 0x00 0x0ad7 0xffff 0x0000.0022c821 0x0180011f
Scn: 0x0000.0022c821
Scn: 0x0000.0022c818
Scn: 0x0000.0022c811
适用 CR块

54. © Copyrights 2001~2016, EXEM CO.,LTD. All Rights Reserved.
Oracle Deep Internal
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