在基于此在LMT(Extent Local Management）下Oracle建议我们使用ASSM（Automatic Segment-Space Management），看看
Oracle doc是如何来解释ASSM的：
This keyword tells Oracle that you want to use bitmaps to manage the free space with in segments. A bitmap, in this case, is a map that describes the status of each data block within a segment with respect to the amount of space in the block available for inserting rows. As more or less space becomes available in a data block, its new state is reflected in the bitmap. Bitmaps enable Oracle to manage free space more automatically; thus, this form of space management is called automatic segment-space management. Locally managed tablespaces using automatic segment-space management can be created as smallfile (traditional) or bigfile tablespaces. AUTO is the default.
在Oracle 10g，在本地管理的表空间中，如果数据库块大小（db_block_size）为16KB或16KB以下，数据文件头保留64KB空间；若是32KB的块大小，则保留128KB。即数据块大小和文件头保留的数据块块数之间的对应关系为：
db_block_size=2 KB，文件头会保留32个数据块；
db_block_size=4 KB，文件头会保留16个数据块；
db_block_size=8 KB，文件头会保留8个数据块；
db_block_size=16 KB，文件头会保留4个数据块；
db_block_size=32 KB，文件头会保留4个数据块。
对于默认8KB块大小的表空间，Oracle保留8个块用于管理，其中数据块1和2用于记录数据文件头信息，数据块3～8用于记录区间的位图信息。
Oracle 11G:0号操作系统块，1-2是文件头，3-127是位图信息。128号开始及之后存放的是数据了—可能是段头或段的数据。
案例：
t2表是test2表空间的第一个segment：
|
1
2
3
4
5
6
7
8
9
|
11
:
24
:
30
SYS@ test1 >col owner
for
a10
11
:
24
:
43
SYS@ test1 >select OWNER,SEGMENT_NAME,TABLESPACE_NAME,FILE_ID,EXTENT_ID,BLOCK_ID,BLOCKS
from
dba_extents
2
*
where
tablespace_name=
'TEST1'
OWNER SEGMENT_NAME TABLESPACE_NAME FILE_ID EXTENT_ID BLOCK_ID BLOCKS
---------- -------------------- ------------------------------ ---------- ---------- ---------- ----------
SCOTT T2 TEST2
8
0
128
8
11
:
10
:
57
SYS@ test1 >alter system dump datafile
3
block min
1
block max
127
;
System altered.
|
DUMP文件（1#块为datafile header）
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
|
Start dump data blocks tsn:
22
file#:
3
minblk
1
maxblk
127
Block
1
(file header)
not
dumped:use dump file header command
Block dump
from
cache:
Dump of buffer cache
at
level
4
for
tsn=
22
, rdba=
12582914
BH (
0x227e9254
) file#:
3
rdba:
0x00c00002
(
3
/
2
)
class
:
13
ba:
0x22516000
set:
3
pool
3
bsz:
8192
bsi:
0
sflg:
1
pwc:
0
,
0
dbwrid:
0
obj:
-1
objn:
3
tsn:
22
afn:
3
hint: f
hash: [
0x2b7af910
,
0x2b7af910
] lru: [
0x227e93d4
,
0x227e9158
]
lru-flags: hot_buffer
obj-flags: object_ckpt_list
ckptq: [
0x223e3ddc
,
0x2bbe3ba4
] fileq: [
0x223e3de4
,
0x2bbe3be0
] objq: [
0x27fa8800
,
0x223e4b0c
]
st: XCURRENT md: NULL tch:
0
flags: buffer_dirty redo_since_read
LRBA: [
0x34.
188.0
] LSCN: [
0x0.
a2349c] HSCN: [
0x0.
a2349c] HSUB: [
1
]
cr pin refcnt:
0
sh pin refcnt:
0
Block dump
from
disk:
buffer tsn:
22
rdba:
0x00c00002
(
3
/
2
)
scn:
0x0000.
0096c8a5 seq:
0x02
flg:
0x04
tail:
0xc8a51d02
frmt:
0x02
chkval:
0x72e8
type:
0x1d
=KTFB Bitmapped File Space Header
Hex dump of block: st=
0
, typ_found=
1
Dump of memory
from
0x00758200
to
0x0075A200
758200
0000A21D 00C00002 0096C8A5
04020000
[................]
758210
000072E8
00000003
00000008
00000500
[.r..............]
758220
00000001
00000000
00000000
0000007E [............~...]
758230
000004FF
00000000
00000090
0096C8A4 [................]
758240
00000000
00000000
00000000
00000000
[................]
758250
00000080
00000008
00000000
00000000
[................]
758260
00000000
00000000
00000000
00000000
[................]
Repeat
504
times
75A1F0
00000000
00000000
00000000
C8A51D02 [................]
File Space Header Block:
Header Control:
RelFno:
3
, Unit:
8
, Size:
1280
, Flag:
1
AutoExtend: NO, Increment:
0
, MaxSize:
0
Initial Area:
126
, Tail:
1279
, First:
0
, Free:
144
Deallocation scn:
9881764.0
Header Opcode:
Save: No Pending Op
|
block# 127:
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
|
Block dump
from
cache:
Dump of buffer cache
at
level
4
for
tsn=
22
, rdba=
12583039
Block dump
from
disk:
buffer tsn:
22
rdba:
0x00c0007f
(
3
/
127
)
scn:
0x0000.
0090e601
seq:
0x01
flg:
0x04
tail:
0xe6011e01
frmt:
0x02
chkval:
0x4373
type:
0x1e
=KTFB Bitmapped File Space Bitmap
Hex dump of block: st=
0
, typ_found=
1
Dump of memory
from
0x00758200
to
0x0075A200
758200
0000A21E 00C0007F
0090E601
04010000
[................]
758210
00004373
00000003
03C10080
00000000
[sC..............]
758220
00000000
0000F800
00000000
00000000
[................]
758230
00000000
00000000
00000000
00000000
[................]
Repeat
507
times
75A1F0
00000000
00000000
00000000
E6011E01 [................]
File Space Bitmap Block:
BitMap Control:
RelFno:
3
, BeginBlock:
62980224
, Flag:
0
, First:
0
, Free:
63488
0000000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
0000000000000000
|
案例分析：
1、查看emp表存储信息
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
|
17
:
31
:
39
SYS@ test1 >col segment_name
for
a20
17
:
33
:
01
SYS@ test1 >select owner,segment_name,segment_type,tablespace_name,bytes/
1024
from
dba_segments
17
:
33
:
24
2
where
segment_name=
'EMP'
;
OWNER SEGMENT_NAME SEGMENT_TYPE TABLESPACE_NAME BYTES/
1024
------------------------------ -------------------- ------------------ ------------------------------ ----------
SCOTT EMP TABLE USERS
64
17
:
31
:
06
SYS@ test1 >select tablespace_name,contents,extent_management,SEGMENT_SPACE_MANAGEMENT
from
dba_tablespaces;
TABLESPACE_NAME CONTENTS EXTENT_MAN SEGMEN
------------------------------ --------- ---------- ------
SYSTEM PERMANENT DICTIONARY MANUAL
USERS PERMANENT LOCAL AUTO
17
:
37
:
42
SYS@ test1 >COL OWNER FOR A10
17
:
37
:
54
SYS@ test1 >R
1
select owner,SEGMENT_NAME,EXTENT_ID, FILE_ID,BLOCK_ID,BLOCKS
from
dba_extents
2
*
where
segment_name=
'EMP'
OWNER SEGMENT_NAME EXTENT_ID FILE_ID BLOCK_ID BLOCKS
---------- -------------------------------------------------- ---------- ---------- ---------- ----------
SCOTT EMP
0
4
144
8
17
:
16
:
05
SYS@ test1 >select header_file,header_block,blocks,extents
from
dba_segments
where
segment_name=
'EMP'
;
HEADER_FILE HEADER_BLOCK BLOCKS EXTENTS
----------- ------------ ---------- ----------
4
146
8
1
|
从以上可以看到，emp表存储在users表空间上，users表空间采用LMT管理；所以对于emp表，其segment space采用auto方式。起始block为144，segment header block为146.
2、对emp表中的block进行dump分析
17:39:30 SYS@ test1 >alter system dump datafile 4 block min 144 block max 151;
System altered.
查看dump的trace文件：
[oracle@RH6 ~]$ ls -lt /u01/app/oracle/diag/rdbms/test1/test1/trace/|more
total 56908
-rw-r----- 1 oracle oinstall 25923 Dec 15 17:42 test1_ora_2385.trc
[oracle@RH6 ~]$ more /u01/app/oracle/diag/rdbms/test1/test1/trace/test1_ora_2385.trc
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
|
Trace file /u01/app/oracle/diag/rdbms/test1/test1/trace/test1_ora_2385.trc
Oracle Database 11g Enterprise Edition Release
11.2.
0.1.
0
- Production
With the Partitioning, OLAP, Data Mining
and
Real Application Testing options
ORACLE_HOME = /u01/app/oracle/product/
11.2.
0
/db_1
System name: Linux
Node name: rh6.cuug.net
Release:
2.6.
32
-71.
el6.i686
Version: #
1
SMP Wed Sep
1
01
:
26
:
34
EDT
2010
Machine: i686
Instance name: test1
Redo thread mounted by
this
instance:
1
Oracle process number:
0
Unix process pid:
2385
, image: oracle@rh6.cuug.net
***
2014
-04
-22
10
:
33
:
45.255
Breaking the connection
before
proto/dty negotiation, error raised
3113
Trace file /u01/app/oracle/diag/rdbms/test1/test1/trace/test1_ora_2385.trc
Oracle Database 11g Enterprise Edition Release
11.2.
0.1.
0
- Production
With the Partitioning, OLAP, Data Mining
and
Real Application Testing options
ORACLE_HOME = /u01/app/oracle/product/
11.2.
0
/db_1
System name: Linux
Node name: RH6.cuug.net
Release:
2.6.
32
-71.
el6.i686
Version: #
1
SMP Wed Sep
1
01
:
26
:
34
EDT
2010
Machine: i686
Instance name: test1
Redo thread mounted by
this
instance:
1
Oracle process number:
17
Unix process pid:
2385
, image: oracle@RH6.cuug.net (TNS V1-V3)
***
2014
-12
-15
17
:
35
:
47.781
*** SESSION ID:(
1.5
)
2014
-12
-15
17
:
35
:
47.781
*** CLIENT ID:()
2014
-12
-15
17
:
35
:
47.781
*** SERVICE NAME:()
2014
-12
-15
17
:
35
:
47.781
*** MODULE NAME:(sqlplus@RH6.cuug.net (TNS V1-V3))
2014
-12
-15
17
:
35
:
47.781
*** ACTION NAME:()
2014
-12
-15
17
:
35
:
47.781
Thread
1
checkpoint: logseq
41
, block
2
, scn
10122512
cache-low rba: logseq
41
, block
7060
on
-disk rba: logseq
41
, block
7085
, scn
10126253
change track rba: logseq
41
, block
7085
, scn
10126337
start recovery
at
logseq
41
, block
7060
, scn
0
***
2014
-12
-15
17
:
35
:
47.995
Started writing zeroblks thread
1
seq
41
blocks
7085
-7092
***
2014
-12
-15
17
:
35
:
48.030
Completed writing zeroblks thread
1
seq
41
==== Redo read statistics
for
thread
1
====
Total physical reads (
from
disk
and
memory): 4096Kb
-- Redo read_disk statistics --
Read rate (ASYNC): 12Kb
in
0.
25s =>
0.05
Mb/sec
Longest record: 1Kb, moves:
0
/
41
(
0
%)
Change moves:
1
/
11
(
9
%), moved: 0Mb
Longest LWN: 9Kb, moves:
0
/
3
(
0
%), moved: 0Mb
Last redo scn:
0x0000.
009a83ac (
10126252
)
----------------------------------------------
----- Recovery Hash Table Statistics ---------
Hash table buckets =
32768
Longest hash chain =
1
Average hash chain =
25
/
25
=
1.0
Max compares per lookup =
1
Avg compares per lookup =
30
/
67
=
0.4
----------------------------------------------
***
2014
-12
-15
17
:
35
:
48.085
KCRA: start recovery claims
for
25
data blocks
***
2014
-12
-15
17
:
35
:
48.256
KCRA: blocks processed =
25
/
25
, claimed =
25
, eliminated =
0
***
2014
-12
-15
17
:
35
:
48.257
Recovery of Online Redo Log: Thread
1
Group
4
Seq
41
Reading mem
0
***
2014
-12
-15
17
:
35
:
48.382
Completed redo application of
0.
01MB
***
2014
-12
-15
17
:
35
:
50.522
Completed recovery checkpoint
IR RIA: redo_size
12288
bytes, time_taken
267
ms
----- Recovery Hash Table Statistics ---------
Hash table buckets =
32768
Longest hash chain =
1
Average hash chain =
25
/
25
=
1.0
Max compares per lookup =
1
Avg compares per lookup =
47
/
55
=
0.9
----------------------------------------------
Recovery sets nab of thread
1
seq
41
to
7085
with
8
zeroblks
***
2014
-12
-15
17
:
36
:
09.120
kwqmnich: current time::
9
:
36
:
8
:
0
kwqmnich: instance no
0
repartition flag
1
kwqmnich: initialized job cache structure
kwqinfy: Call kwqrNondurSubInstTsk
***
2014
-12
-15
17
:
42
:
08.722
Start dump data blocks tsn:
4
file#:
4
minblk
144
maxblk
151
Block dump
from
cache:
Dump of buffer cache
at
level
4
for
tsn=
4
, rdba=
16777360
|
Block dump from disk:
buffer tsn: 4 rdba: 0x01000090 (4/144)
scn: 0x0000.0096c992 seq: 0x02 flg: 0x04 tail: 0xc9922002
frmt: 0x02 chkval: 0x4bc8 type: 0x20=FIRST LEVEL BITMAP BLOCK
其中在第144个block的dump信息中我们发现type: 0x20=FIRST LEVEL BITMAP BLOCK，说明这个block是第一级bitmap block，Oracle用第一级bitmap block来管理data block的使用情况：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
|
Hex dump of block: st=
0
, typ_found=
1
Dump of memory
from
0x008E8200
to
0x008EA200
8E8200
0000A220
01000090
0096C992
04020000
[ ...............]
8E8210
00004BC8
00000000
00000000
00000000
[.K..............]
8E8220
00000000
00000000
00000000
00000000
[................]
Repeat
1
times
8E8240
00000000
00000000
00000000
00000004
[................]
8E8250
FFFFFFFF
00000000
00000003
00000008
[................]
8E8260
00010001
00000000
00000000
00000000
[................]
8E8270
00000005
00000003
54682010
54682010
[......... hT. hT]
8E8280
00000000
00000000
00000000
00000000
[................]
8E8290
01000091
00000000
00000000
00000008
[................]
8E82A0
00000008
01000098
00000000
00000000
[................]
8E82B0
00000000
00000005
00000000
00000001
[................]
8E82C0 000044A3 0096C903
00000000
01000090
[.D..............]
8E82D0
00000008
00000000
00000000
00000000
[................]
8E82E0
00000000
00000000
00000000
00000000
[................]
Repeat
9
times
8E8380
00000000
00000000
00000000
55551511
[..............UU]
8E8390
00000000
00000000
00000000
00000000
[................]
Repeat
485
times
8EA1F0
00000000
00000000
00000000
C9922002 [............. ..]
Dump of First Level Bitmap Block
--------------------------------
nbits :
4
nranges:
1
parent dba:
0x01000091
poffset:
0
unformatted:
0
total:
8
first
useful block:
3
owning instance :
1
instance ownership changed
at
11
/
16
/
2014
11
:
54
:
56
Last successful Search
11
/
16
/
2014
11
:
54
:
56
Freeness Status: nf1
0
nf2
0
nf3
0
nf4
5
Extent Map Block Offset:
4294967295
First free datablock :
3
Bitmap block lock opcode
0
Locker xid: :
0x0000.
000.00000000
Inc #:
0
Objd:
17571
HWM Flag: HWM Set
Highwater::
0x01000098
ext#:
0
blk#:
8
ext size:
8
#blocks
in
seg. hdr's freelists:
0
#blocks below:
5
mapblk
0x00000000
offset:
0
--------------------------------------------------------
DBA Ranges :
--------------------------------------------------------
0x01000090
Length:
8
Offset:
0
0
:Metadata
1
:Metadata
2
:Metadata
3
:
75
-100
% free
4
:
75
-100
% free
5
:
75
-100
% free
6
:
75
-100
% free
7
:
75
-100
% free
--------------------------------------------------------
Block dump
from
cache:
Dump of buffer cache
at
level
4
for
tsn=
4
, rdba=
16777361
|
Block dump from disk:
buffer tsn: 4 rdba: 0x01000091 (4/145)
scn: 0x0000.0096c97a seq: 0x02 flg: 0x04 tail: 0xc97a2102
frmt: 0x02 chkval: 0xc282 type: 0x21=SECOND LEVEL BITMAP BLOCK
145＃block的类型是：type: 0x21=SECOND LEVEL BITMAP BLOCK，说明该block是二级bitmap block，他是用来管理一级bitmap block的。
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
|
Hex dump of block: st=
0
, typ_found=
1
Dump of memory
from
0x008E8200
to
0x008EA200
8E8200
0000A221
01000091
0096C97A
04020000
[!.......z.......]
8E8210
0000C282
00000000
00000000
00000000
[................]
8E8220
00000000
00000000
00000000
00000000
[................]
Repeat
1
times
8E8240
00000000
00000000
00000000
01000092
[................]
8E8250
00000001
00000001
00000000
00000000
[................]
8E8260
00000000
00000000
000044A3
00000001
[.........D......]
8E8270
00000000
01000090
00010005
00000000
[................]
8E8280
00000000
00000000
00000000
00000000
[................]
Repeat
502
times
8EA1F0
00000000
00000000
00000000
C97A2102 [.............!z.]
Dump of Second Level Bitmap Block
number:
1
nfree:
1
ffree:
0
pdba:
0x01000092
Inc #:
0
Objd:
17571
opcode:
0
xid:
L1 Ranges :
--------------------------------------------------------
0x01000090
Free:
5
Inst:
1
--------------------------------------------------------
Block dump
from
cache:
Dump of buffer cache
at
level
4
for
tsn=
4
, rdba=
16777362
BH (
0x23bfb924
) file#:
4
rdba:
0x01000092
(
4
/
146
)
class
:
4
ba:
0x23bde000
set:
2
pool
2
bsz:
8192
bsi:
0
sflg:
0
pwc:
0
,
0
dbwrid:
0
obj:
17571
objn:
-1
tsn:
4
afn:
4
hint: f
hash: [
0x23bfba74
,
0x2b7af538
] lru: [
0x23bfbaa4
,
0x2bbdd3b4
]
ckptq: [NULL] fileq: [NULL] objq: [NULL]
st: CR md: NULL tch:
1
cr: [scn:
0x0.
9ad2c6],[xid:
0x0.
0.0
],[uba:
0x0.
0.0
],[cls:
0x0.
9ad2c6],[sfl:
0x0
],[lc:
0x0.
0
]
flags:
cr pin refcnt:
0
sh pin refcnt:
0
BH (
0x23bfb9f8
) file#:
4
rdba:
0x01000092
(
4
/
146
)
class
:
4
ba:
0x23be0000
set:
2
pool
2
bsz:
8192
bsi:
0
sflg:
0
pwc:
0
,
0
dbwrid:
0
obj:
17571
objn:
-1
tsn:
4
afn:
4
hint: f
hash: [
0x2b7af538
,
0x23bfb9a0
] lru: [
0x2bbdd3b4
,
0x23bfb9d0
]
ckptq: [NULL] fileq: [NULL] objq: [NULL]
st: CR md: NULL tch:
1
cr: [scn:
0x0.
9ad2c1],[xid:
0x0.
0.0
],[uba:
0x0.
0.0
],[cls:
0x0.
9ad2c1],[sfl:
0x0
],[lc:
0x0.
0
]
flags:
cr pin refcnt:
0
sh pin refcnt:
0
|
Block dump from disk:
buffer tsn: 4 rdba: 0x01000092 (4/146)
scn: 0x0000.0096c992 seq: 0x03 flg: 0x04 tail: 0xc9922303
frmt: 0x02 chkval: 0xefbe type: 0x23=PAGETABLE SEGMENT HEADER
接下来简单看看146＃block的类型是：
type: 0x23=PAGETABLE SEGMENT HEADER
也就是我们熟悉的segment header block，这里它也同时是一个特殊的三级bitmap block
同时最下面一条非常有用的信息是：
Second Level Bitmap block DBAs
--------------------------------------------------------
DBA 1: 0x01000091
记录了二级btimap block的地址，因为segment小，只有1个二级bitmap block，大家也可以创建一个大一
点的表，主要需要保证要有足够多的block才可能看到第二个二级block出现，要看到出现一个三级bitmap
block可能非常的难。
|
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286
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298
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305
306
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308
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316
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394
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419
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470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
|
Hex dump of block: st=
0
, typ_found=
1
Dump of memory
from
0x008E8200
to
0x008EA200
8E8200
0000A223
01000092
0096C992
04030000
[#...............]
8E8210
0000EFBE
00000000
00000000
00000000
[................]
8E8220
00000000
00000001
00000008
00000A9C [................]
8E8230
00000000
00000008
00000008
01000098
[................]
8E8240
00000000
00000000
00000000
00000005
[................]
8E8250
00000000
00000000
00000000
00000000
[................]
8E8260
00000008
00000008
01000098
00000000
[................]
8E8270
00000000
00000000
00000005
01000090
[................]
8E8280
01000090
00000000
00000000
00000000
[................]
8E8290
00000000
00000000
00000000
00000000
[................]
Repeat
3
times
8E82D0
00000001
00002000
00000000
00001434
[..... .....
.4.
..]
8E82E0
00000000
01000091
00000001
01000090
[................]
8E82F0
01000091
00000000
00000000
00000000
[................]
8E8300
00000000
00000000
00000001
00000000
[................]
8E8310
000044A3
10000000
01000090
00000008
[.D..............]
8E8320
00000000
00000000
00000000
00000000
[................]
Repeat
152
times
8E8CB0
01000090
01000093
00000000
00000000
[................]
8E8CC0
00000000
00000000
00000000
00000000
[................]
Repeat
151
times
8E9640
00000000
00000000
01000091
00000000
[................]
8E9650
00000000
00000000
00000000
00000000
[................]
Repeat
185
times
8EA1F0
00000000
00000000
00000000
C9922303 [.............#..]
Extent Control Header
-----------------------------------------------------------------
Extent Header:: spare1:
0
spare2:
0
#extents:
1
#blocks:
8
last
map
0x00000000
#maps:
0
offset:
2716
Highwater::
0x01000098
ext#:
0
blk#:
8
ext size:
8
#blocks
in
seg. hdr's freelists:
0
#blocks below:
5
mapblk
0x00000000
offset:
0
Unlocked
--------------------------------------------------------
Low HighWater Mark :
Highwater::
0x01000098
ext#:
0
blk#:
8
ext size:
8
#blocks
in
seg. hdr's freelists:
0
#blocks below:
5
mapblk
0x00000000
offset:
0
Level
1
BMB
for
High HWM block:
0x01000090
Level
1
BMB
for
Low HWM block:
0x01000090
--------------------------------------------------------
Segment Type:
1
nl2:
1
blksz:
8192
fbsz:
0
L2 Array start offset:
0x00001434
First Level
3
BMB:
0x00000000
L2 Hint
for
inserts:
0x01000091
Last Level
1
BMB:
0x01000090
Last Level II BMB:
0x01000091
Last Level III BMB:
0x00000000
Map Header:: next
0x00000000
#extents:
1
obj#:
17571
flag:
0x10000000
Inc #
0
Extent Map
-----------------------------------------------------------------
0x01000090
length:
8
Auxillary Map
--------------------------------------------------------
Extent
0
: L1 dba:
0x01000090
Data dba:
0x01000093
--------------------------------------------------------
Second Level Bitmap block DBAs
--------------------------------------------------------
DBA
1
:
0x01000091
Block dump
from
cache:
Dump of buffer cache
at
level
4
for
tsn=
4
, rdba=
16777363
Block dump
from
disk:
buffer tsn:
4
rdba:
0x01000093
(
4
/
147
)
scn:
0x0000.
0096c992 seq:
0x02
flg:
0x04
tail:
0xc9920602
frmt:
0x02
chkval:
0xcd6c
type:
0x06
=trans data
Hex dump of block: st=
0
, typ_found=
1
Dump of memory
from
0x008E8200
to
0x008EA200
8E8200
0000A206
01000093
0096C992
04020000
[................]
8E8210
0000CD6C
00000001
000044A3 0096C992 [l........D......]
8E8220
00000000
00320002
01000090
00000000
[.....
.2.
........]
8E8230
00000000
00000000
00000000
00000000
[................]
Repeat
2
times
8E8260
00000000
00000000
000EFFFF 1F8A1F98 [................]
8E8270
00001F8A
00000000
00000000
00000000
[................]
8E8280
00000000
00000000
00000000
00000000
[................]
Repeat
502
times
8EA1F0
00000000
00000000
00000000
C9920602 [................]
Block header dump:
0x01000093
Object id
on
Block? Y
seg/obj:
0x44a3
csc:
0x00.
96c992 itc:
2
flg: E typ:
1
- DATA
brn:
0
bdba:
0x1000090
ver:
0x01
opc:
0
inc:
0
exflg:
0
Itl Xid Uba Flag Lck Scn/Fsc
0x01
0x0000.
000.00000000
0x00000000.
0000.00
----
0
fsc
0x0000.
00000000
0x02
0x0000.
000.00000000
0x00000000.
0000.00
----
0
fsc
0x0000.
00000000
--11G默认用快速提交，Flag是U，正常提交是C。
--Itl: ITL事务槽号的流水编号
--Xid：transac[X]tion identified(事务ID),由und的段号+undo的槽号+undo槽号的覆盖次数三部分组成
--Uba：undo block address记录了最近一次的该记录的前镜像（修改前的值）
--Flag：C是提交，U是快速提交，---是未提交（Flg C=Committed U=Commit Upper Bound T=Active
at
CSC）
--Lck：锁住了几行数据，对应有几个行锁
--Scn/Fsc：Scn=SCN of commited TX; Fsc=Free space credit(bytes)
--SCN WRAP:如果事务已提交并完成清洗，该字段保存事务提交SCN的SCN WRAP部分，否则该字段保存空闲预支字节数(FSC).比如删除了一行数据
10
个字节，在事务提前前，这
10
个字节就属于fsc（即会写到SCN WRAP），只有事务提交后，才能正式返回到空闲空间。
bdba:
0x01000093
data_block_dump,data header
at
0x8e8264
===============
tsiz:
0x1f98
hsiz:
0xe
pbl:
0x008e8264
76543210
flag=--------
ntab=
0
nrow=
0
frre=
-1
fsbo=
0xe
fseo=
0x1f98
avsp=
0x1f8a
tosp=
0x1f8a
block_row_dump:
end_of_block_dump
Block dump
from
cache:
Dump of buffer cache
at
level
4
for
tsn=
4
, rdba=
16777364
Block dump
from
disk:
buffer tsn:
4
rdba:
0x01000094
(
4
/
148
)
scn:
0x0000.
0096c992 seq:
0x02
flg:
0x04
tail:
0xc9920602
frmt:
0x02
chkval:
0xcd6b
type:
0x06
=trans data
Hex dump of block: st=
0
, typ_found=
1
Dump of memory
from
0x008E8200
to
0x008EA200
8E8200
0000A206
01000094
0096C992
04020000
[................]
8E8210
0000CD6B
00000001
000044A3 0096C992 [k........D......]
8E8220
00000000
00320002
01000090
00000000
[.....
.2.
........]
8E8230
00000000
00000000
00000000
00000000
[................]
Repeat
2
times
8E8260
00000000
00000000
000EFFFF 1F8A1F98 [................]
8E8270
00001F8A
00000000
00000000
00000000
[................]
8E8280
00000000
00000000
00000000
00000000
[................]
Repeat
502
times
8EA1F0
00000000
00000000
00000000
C9920602 [................]
Block header dump:
0x01000094
Object id
on
Block? Y
seg/obj:
0x44a3
csc:
0x00.
96c992 itc:
2
flg: E typ:
1
- DATA
brn:
0
bdba:
0x1000090
ver:
0x01
opc:
0
inc:
0
exflg:
0
Itl Xid Uba Flag Lck Scn/Fsc
0x01
0x0000.
000.00000000
0x00000000.
0000.00
----
0
fsc
0x0000.
00000000
0x02
0x0000.
000.00000000
0x00000000.
0000.00
----
0
fsc
0x0000.
00000000
bdba:
0x01000094
data_block_dump,data header
at
0x8e8264
===============
tsiz:
0x1f98
hsiz:
0xe
pbl:
0x008e8264
76543210
flag=--------
ntab=
0
nrow=
0
frre=
-1
fsbo=
0xe
fseo=
0x1f98
avsp=
0x1f8a
tosp=
0x1f8a
block_row_dump:
end_of_block_dump
Block dump
from
cache:
Dump of buffer cache
at
level
4
for
tsn=
4
, rdba=
16777365
Block dump
from
disk:
buffer tsn:
4
rdba:
0x01000095
(
4
/
149
)
scn:
0x0000.
009722f6 seq:
0x01
flg:
0x04
tail:
0x22f60601
frmt:
0x02
chkval:
0x52a5
type:
0x06
=trans data
Hex dump of block: st=
0
, typ_found=
1
Dump of memory
from
0x008E8200
to
0x008EA200
8E8200
0000A206
01000095
009722F6
04010000
[........."......]
8E8210
000052A5
00000001
000044A3 009722F6 [.R.......D..."..]
8E8220
00000000
00320002
01000090
001F001B [.....
.2.
........]
8E8230
0000007A 01C01C55
00230121
0000A000 [z...U...!.#.....]
8E8240
00971D50
00000000
00000000
00000000
[P...............]
8E8250
00000000
00000000
00000000
00000000
[................]
8E8260
00000000
000E0100
002EFFFF 1D331D61 [............a
.3.
]
8E8270
00001D33 1F72000E 1F1C1F47 1EC61EF3 [
3.
....r.G.......]
8E8280
1E741E9D 1E261E4C 1DD51DFB 1D881DAF [..t.L.&.........]
8E8290
00001D61
00000000
00000000
00000000
[a...............]
8E82A0
00000000
00000000
00000000
00000000
[................]
Repeat
465
times
8E9FC0
00000000
08002C00 2350C203 4C494D06 [.....,....P#.MIL]
8E9FD0 0552454C 52454C43 4EC2034B B6770753 [LER.CLERK..NS.w.]
8E9FE0
01011701
0EC20201 0BC102FF 0308002C [............,...]
8E9FF0 040350C2 44524F46
414E4107
5453594C [.P..FORD.ANALYST]
8EA000 434CC203 0CB57707
01010103
FF1FC202 [..LC.w..........]
8EA010 2C15C102 C2020800 414A0550 0553454D [...,....P.JAMES.]
8EA020 52454C43 4DC2034B B5770763 0101030C [CLERK..Mc.w.....]
8EA030 0AC20301 C102FF33 08002C1F 4D4FC203 [...
.3.
...,....OM]
8EA040
41444105
4305534D 4B52454C 594EC203 [.ADAMS.CLERK..NY]
8EA050 05BB7707
01010117
FF0CC202 2C15C102 [.w.............,]
8EA060 C2030800 54062D4F
454E5255
41530852
[....O-.TURNER.SA]
8EA070 4D53454C C2034E41 7707634D 010809B5 [LESMAN..Mc.w....]
8EA080 C2020101
02800110
002C1FC1 4FC20308 [..........,....O]
8EA090 494B0428 5009474E
49534552
544E4544
[(.KING.PRESIDENT]
8EA0A0 B57707FF 0101110B 33C20201 0BC102FF [..w.......
.3.
...]
8EA0B0 0308002C 05594EC2 544F4353
4E410754
[,....NY.SCOTT.AN]
8EA0C0 53594C41 4CC20354 BB770743
01011304
[ALYST..LC.w.....]
8EA0D0 1FC20201 15C102FF 0308002C 05534EC2 [........,....NS.]
8EA0E0 52414C43 414D074B 4547414E 4FC20352 [CLARK.MANAGER..O]
8EA0F0 B5770728
01010906
19C20301 C102FF33 [(.w........
.3.
..]
8EA100 08002C0B 634DC203 414C4205 4D07454B [.,....Mc.BLAKE.M]
8EA110
47414E41
C2035245 7707284F 010105B5 [ANAGER..O(.w....]
8EA120 C2030101 02FF331D 002C1FC1 4DC20308 [....
.3.
...,....M]
8EA130 414D0637
4E495452
4C415308 414D5345 [
7.
MARTIN.SALESMA]
8EA140 4DC2034E B5770763 01011C09 0DC20301 [N..Mc.w.........]
8EA150 0FC20233 2C1FC102 C2030800 4A05434C [
3.
.....,....LC.J]
8EA160 53454E4F 4E414D07
52454741
284FC203 [ONES.MANAGER..O(]
8EA170 04B57707
01010102
4C1EC203 15C102FF [.w.........L....]
8EA180 0308002C 04164CC2
44524157
4C415308 [,....L..WARD.SAL]
8EA190 414D5345 4DC2034E B5770763
01011602
[ESMAN..Mc.w.....]
8EA1A0 0DC20301 06C20233 2C1FC102 C2030800 [...
.3.
.....,....]
8EA1B0 4105644B 4E454C4C 4C415308 414D5345 [Kd.ALLEN.SALESMA]
8EA1C0 4DC2034E B5770763
01011402
11C20201 [N..Mc.w.........]
8EA1D0 0204C202 002C1FC1 4AC20308 4D530546 [......,....JF.SM]
8EA1E0
05485449
52454C43 50C2034B B4770703 [ITH.CLERK..P..w.]
8EA1F0 0101110C 09C20201 15C102FF 22F60601 [..............."]
Block header dump:
0x01000095
Object id
on
Block? Y
seg/obj:
0x44a3
csc:
0x00.
9722f6 itc:
2
flg: E typ:
1
- DATA
brn:
0
bdba:
0x1000090
ver:
0x01
opc:
0
inc:
0
exflg:
0
Itl Xid Uba Flag Lck Scn/Fsc
0x01
0x001b.
01f.0000007a
0x01c01c55.
0121.23
C-U-
0
scn
0x0000.
00971d50
0x02
0x0000.
000.00000000
0x00000000.
0000.00
----
0
fsc
0x0000.
00000000
bdba:
0x01000095
data_block_dump,data header
at
0x8e8264
===============
tsiz:
0x1f98
hsiz:
0x2e
pbl:
0x008e8264
76543210
flag=--------
ntab=
1
nrow=
14
frre=
-1
fsbo=
0x2e
fseo=
0x1d61
avsp=
0x1d33
tosp=
0x1d33
0xe
:pti[
0
] nrow=
14
offs=
0
0x12
:pri[
0
] offs=
0x1f72
0x14
:pri[
1
] offs=
0x1f47
0x16
:pri[
2
] offs=
0x1f1c
0x18
:pri[
3
] offs=
0x1ef3
0x1a
:pri[
4
] offs=
0x1ec6
0x1c
:pri[
5
] offs=
0x1e9d
0x1e
:pri[
6
] offs=
0x1e74
0x20
:pri[
7
] offs=
0x1e4c
0x22
:pri[
8
] offs=
0x1e26
0x24
:pri[
9
] offs=
0x1dfb
0x26
:pri[
10
] offs=
0x1dd5
0x28
:pri[
11
] offs=
0x1daf
0x2a
:pri[
12
] offs=
0x1d88
0x2c
:pri[
13
] offs=
0x1d61
block_row_dump:
tab
0
, row
0
, @
0x1f72
tl:
38
fb: --H-FL-- lb:
0x0
cc:
8
col
0
: [
3
] c2 4a
46
col
1
: [
5
]
53
4d
49
54
48
col
2
: [
5
]
43
4c
45
52
4b
col
3
: [
3
] c2
50
03
col
4
: [
7
]
77
b4 0c
11
01
01
01
col
5
: [
2
] c2
09
col
6
: *NULL*
col
7
: [
2
] c1
15
tab
0
, row
1
, @
0x1f47
tl:
43
fb: --H-FL-- lb:
0x0
cc:
8
col
0
: [
3
] c2 4b
64
col
1
: [
5
]
41
4c 4c
45
4e
col
2
: [
8
]
53
41
4c
45
53
4d
41
4e
col
3
: [
3
] c2 4d
63
col
4
: [
7
]
77
b5
02
14
01
01
01
col
5
: [
2
] c2
11
col
6
: [
2
] c2
04
col
7
: [
2
] c1 1f
tab
0
, row
2
, @
0x1f1c
tl:
43
fb: --H-FL-- lb:
0x0
cc:
8
col
0
: [
3
] c2 4c
16
col
1
: [
4
]
57
41
52
44
col
2
: [
8
]
53
41
4c
45
53
4d
41
4e
col
3
: [
3
] c2 4d
63
col
4
: [
7
]
77
b5
02
16
01
01
01
col
5
: [
3
] c2 0d
33
col
6
: [
2
] c2
06
col
7
: [
2
] c1 1f
tab
0
, row
3
, @
0x1ef3
tl:
41
fb: --H-FL-- lb:
0x0
cc:
8
col
0
: [
3
] c2 4c
43
col
1
: [
5
] 4a 4f 4e
45
53
col
2
: [
7
] 4d
41
4e
41
47
45
52
col
3
: [
3
] c2 4f
28
col
4
: [
7
]
77
b5
04
02
01
01
01
col
5
: [
3
] c2 1e 4c
col
6
: *NULL*
col
7
: [
2
] c1
15
tab
0
, row
4
, @
0x1ec6
tl:
45
fb: --H-FL-- lb:
0x0
cc:
8
col
0
: [
3
] c2 4d
37
col
1
: [
6
] 4d
41
52
54
49
4e
col
2
: [
8
]
53
41
4c
45
53
4d
41
4e
col
3
: [
3
] c2 4d
63
col
4
: [
7
]
77
b5
09
1c
01
01
01
col
5
: [
3
] c2 0d
33
col
6
: [
2
] c2 0f
col
7
: [
2
] c1 1f
tab
0
, row
5
, @
0x1e9d
tl:
41
fb: --H-FL-- lb:
0x0
cc:
8
col
0
: [
3
] c2 4d
63
col
1
: [
5
]
42
4c
41
4b
45
col
2
: [
7
] 4d
41
4e
41
47
45
52
col
3
: [
3
] c2 4f
28
col
4
: [
7
]
77
b5
05
01
01
01
01
col
5
: [
3
] c2 1d
33
col
6
: *NULL*
col
7
: [
2
] c1 1f
tab
0
, row
6
, @
0x1e74
tl:
41
fb: --H-FL-- lb:
0x0
cc:
8
col
0
: [
3
] c2 4e
53
col
1
: [
5
]
43
4c
41
52
4b
col
2
: [
7
] 4d
41
4e
41
47
45
52
col
3
: [
3
] c2 4f
28
col
4
: [
7
]
77
b5
06
09
01
01
01
col
5
: [
3
] c2
19
33
col
6
: *NULL*
col
7
: [
2
] c1 0b
tab
0
, row
7
, @
0x1e4c
tl:
40
fb: --H-FL-- lb:
0x0
cc:
8
col
0
: [
3
] c2 4e
59
col
1
: [
5
]
53
43
4f
54
54
col
2
: [
7
]
41
4e
41
4c
59
53
54
col
3
: [
3
] c2 4c
43
col
4
: [
7
]
77
bb
04
13
01
01
01
col
5
: [
2
] c2 1f
col
6
: *NULL*
col
7
: [
2
] c1
15
tab
0
, row
8
, @
0x1e26
tl:
38
fb: --H-FL-- lb:
0x0
cc:
8
col
0
: [
3
] c2 4f
28
col
1
: [
4
] 4b
49
4e
47
col
2
: [
9
]
50
52
45
53
49
44
45
4e
54
col
3
: *NULL*
col
4
: [
7
]
77
b5 0b
11
01
01
01
col
5
: [
2
] c2
33
col
6
: *NULL*
col
7
: [
2
] c1 0b
tab
0
, row
9
, @
0x1dfb
tl:
43
fb: --H-FL-- lb:
0x0
cc:
8
col
0
: [
3
] c2 4f 2d
col
1
: [
6
]
54
55
52
4e
45
52
col
2
: [
8
]
53
41
4c
45
53
4d
41
4e
col
3
: [
3
] c2 4d
63
col
4
: [
7
]
77
b5
09
08
01
01
01
col
5
: [
2
] c2
10
col
6
: [
1
]
80
col
7
: [
2
] c1 1f
tab
0
, row
10
, @
0x1dd5
tl:
38
fb: --H-FL-- lb:
0x0
cc:
8
col
0
: [
3
] c2 4f 4d
col
1
: [
5
]
41
44
41
4d
53
col
2
: [
5
]
43
4c
45
52
4b
col
3
: [
3
] c2 4e
59
col
4
: [
7
]
77
bb
05
17
01
01
01
col
5
: [
2
] c2 0c
col
6
: *NULL*
col
7
: [
2
] c1
15
tab
0
, row
11
, @
0x1daf
tl:
38
fb: --H-FL-- lb:
0x0
cc:
8
col
0
: [
2
] c2
50
col
1
: [
5
] 4a
41
4d
45
53
col
2
: [
5
]
43
4c
45
52
4b
col
3
: [
3
] c2 4d
63
col
4
: [
7
]
77
b5 0c
03
01
01
01
col
5
: [
3
] c2 0a
33
col
6
: *NULL*
col
7
: [
2
] c1 1f
tab
0
, row
12
, @
0x1d88
tl:
39
fb: --H-FL-- lb:
0x0
cc:
8
col
0
: [
3
] c2
50
03
col
1
: [
4
]
46
4f
52
44
col
2
: [
7
]
41
4e
41
4c
59
53
54
col
3
: [
3
] c2 4c
43
col
4
: [
7
]
77
b5 0c
03
01
01
01
col
5
: [
2
] c2 1f
col
6
: *NULL*
col
7
: [
2
] c1
15
tab
0
, row
13
, @
0x1d61
tl:
39
fb: --H-FL-- lb:
0x0
cc:
8
col
0
: [
3
] c2
50
23
col
1
: [
6
] 4d
49
4c 4c
45
52
col
2
: [
5
]
43
4c
45
52
4b
col
3
: [
3
] c2 4e
53
col
4
: [
7
]
77
b6
01
17
01
01
01
col
5
: [
2
] c2 0e
col
6
: *NULL*
col
7
: [
2
] c1 0b
end_of_block_dump
Block dump
from
cache:
Dump of buffer cache
at
level
4
for
tsn=
4
, rdba=
16777366
Block dump
from
disk:
buffer tsn:
4
rdba:
0x01000096
(
4
/
150
)
scn:
0x0000.
0096c992 seq:
0x02
flg:
0x04
tail:
0xc9920602
frmt:
0x02
chkval:
0xcd69
type:
0x06
=trans data
Hex dump of block: st=
0
, typ_found=
1
Dump of memory
from
0x008E8200
to
0x008EA200
8E8200
0000A206
01000096
0096C992
04020000
[................]
8E8210
0000CD69
00000001
000044A3 0096C992 [i........D......]
8E8220
00000000
00320002
01000090
00000000
[.....
.2.
........]
8E8230
00000000
00000000
00000000
00000000
[................]
Repeat
2
times
8E8260
00000000
00000000
000EFFFF 1F8A1F98 [................]
8E8270
00001F8A
00000000
00000000
00000000
[................]
8E8280
00000000
00000000
00000000
00000000
[................]
Repeat
502
times
8EA1F0
00000000
00000000
00000000
C9920602 [................]
Block header dump:
0x01000096
Object id
on
Block? Y
seg/obj:
0x44a3
csc:
0x00.
96c992 itc:
2
flg: E typ:
1
- DATA
brn:
0
bdba:
0x1000090
ver:
0x01
opc:
0
inc:
0
exflg:
0
Itl Xid Uba Flag Lck Scn/Fsc
0x01
0x0000.
000.00000000
0x00000000.
0000.00
----
0
fsc
0x0000.
00000000
0x02
0x0000.
000.00000000
0x00000000.
0000.00
----
0
fsc
0x0000.
00000000
bdba:
0x01000096
data_block_dump,data header
at
0x8e8264
===============
tsiz:
0x1f98
hsiz:
0xe
pbl:
0x008e8264
76543210
flag=--------
ntab=
0
nrow=
0
frre=
-1
fsbo=
0xe
fseo=
0x1f98
avsp=
0x1f8a
tosp=
0x1f8a
block_row_dump:
end_of_block_dump
Block dump
from
cache:
Dump of buffer cache
at
level
4
for
tsn=
4
, rdba=
16777367
Block dump
from
disk:
buffer tsn:
4
rdba:
0x01000097
(
4
/
151
)
scn:
0x0000.
0096c992 seq:
0x02
flg:
0x04
tail:
0xc9920602
frmt:
0x02
chkval:
0xcd68
type:
0x06
=trans data
Hex dump of block: st=
0
, typ_found=
1
Dump of memory
from
0x008E8200
to
0x008EA200
8E8200
0000A206
01000097
0096C992
04020000
[................]
8E8210
0000CD68
00000001
000044A3 0096C992 [h........D......]
8E8220
00000000
00320002
01000090
00000000
[.....
.2.
........]
8E8230
00000000
00000000
00000000
00000000
[................]
Repeat
2
times
8E8260
00000000
00000000
000EFFFF 1F8A1F98 [................]
8E8270
00001F8A
00000000
00000000
00000000
[................]
8E8280
00000000
00000000
00000000
00000000
[................]
Repeat
502
times
8EA1F0
00000000
00000000
00000000
C9920602 [................]
Block header dump:
0x01000097
Object id
on
Block? Y
seg/obj:
0x44a3
csc:
0x00.
96c992 itc:
2
flg: E typ:
1
- DATA
brn:
0
bdba:
0x1000090
ver:
0x01
opc:
0
inc:
0
exflg:
0
Itl Xid Uba Flag Lck Scn/Fsc
0x01
0x0000.
000.00000000
0x00000000.
0000.00
----
0
fsc
0x0000.
00000000
0x02
0x0000.
000.00000000
0x00000000.
0000.00
----
0
fsc
0x0000.
00000000
bdba:
0x01000097
data_block_dump,data header
at
0x8e8264
===============
tsiz:
0x1f98
hsiz:
0xe
pbl:
0x008e8264
76543210
flag=--------
ntab=
0
nrow=
0
frre=
-1
fsbo=
0xe
fseo=
0x1f98
avsp=
0x1f8a
tosp=
0x1f8a
block_row_dump:
end_of_block_dump
End dump data blocks tsn:
4
file#:
4
minblk
144
maxblk
151
|
查看emp表存储记录的block:
|
1
2
3
4
5
6
7
8
9
10
11
12
|
11
:
14
:
36
SYS@ test1 >conn scott/tiger
Connected.
11
:
14
:
39
SCOTT@ test1 >select rowid,ename
from
emp
where
rownum=
1
;
ROWID ENAME
------------------ ----------
AAAESjAAEAAAACVAAA SMITH
11
:
15
:
05
SCOTT@ test1 >select dbms_rowid.ROWID_RELATIVE_FNO(rowid) ,dbms_rowid.ROWID_BLOCK_NUMBER(rowid)
from
emp
where
rownum=
1
;
DBMS_ROWID.ROWID_RELATIVE_FNO(ROWID) DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID)
------------------------------------ ------------------------------------
4
149
|
从以上dump可以看到，第149#块开始用于存储数据（144-148用于segment header）
本文转自 客居天涯 51CTO博客，原文链接：http://blog.51cto.com/tiany/1590788，如需转载请自行联系原作者
