block内部数据存储

王朝other·作者佚名  2008-05-19
窄屏简体版  字體: |||超大  

前言: 在block内部oracle的数据到底是怎么存储的,通过rowid方式的时候又是怎样的,insert/delete/update发生的时候又是怎样的,想仔细探讨一下

先交代block里面数据的基本结构:

SQL create table tn(a number, b varchar2(1000));

Table created.

SQL insert into tn select rownum, 'wwweeerrrttt' from all_tables where rownum < 11;

10 rows created.

SQL commit;

Commit complete.

SQL exec show_space('tn');

Free Blocks.............................1

Total Blocks............................16

Total Bytes.............................131072

Unused Blocks...........................14

Unused Bytes............................114688

Last Used Ext FileId....................3

Last Used Ext BlockId...................1954

Last Used Block.........................2

SQL alter system dump datafile 3 block

1955;

System altered.

Block header dump:

0x00c007a3

Object id on Block? Y

seg/obj: 0x66b7

csc: 0x00.1891b8a

itc: 1

flg: O

typ: 1 - DATA

fsl: 0

fnx: 0x0 ver: 0x01

Itl

Xid

Uba

Flag

Lck

Scn/Fsc

0x01

xid:

0x0001.011.000000e8

uba: 0x00803494.0147.07

--U-

10

fsc 0x0000.01891b8c

data_block_dump

===============

tsiz: 0x1fb8

hsiz: 0x26

pbl: 0x0ba76c44

bdba: 0x00c007a3

flag=-----------

ntab=1

nrow=10

frre=-1

fsbo=0x26

fseo=0x1efa

avsp=0x1ed4

tosp=0x1ed4

0xe:pti[0]

nrow=10

offs=0

本块存在10条记录

0x12:pri[0]

offs=0x1efa

----

记录的起始物理位置

0x14:pri[1]

offs=0x1f0d

0x16:pri[2]

offs=0x1f20

0x18:pri[3]

offs=0x1f33

0x1a:pri[4]

offs=0x1f46

0x1c:pri[5]

offs=0x1f59

0x1e:pri[6]

offs=0x1f6c

0x20:pri[7]

offs=0x1f7f

0x22:pri[8]

offs=0x1f92

0x24:pri[9]

offs=0x1fa5

block_row_dump:

tab 0, row 0, @0x1efa tl: 19 fb: --H-FL-- lb: 0x1 cc: 2 --- --

lb: 表示属于XID 0x1,cc 表示有2个字段

col

0: [ 2]

c1 02

----

字段1 长度为2,数据为 c1

02

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

---- 字段而长度 12[/COLOR]

tab 0, row 1, @0x1f0d

tl: 19 fb: --H-FL-- lb: 0x1 cc: 2

col

0: [ 2]

c1 03

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

tab 0, row 2, @0x1f20

tl: 19 fb: --H-FL-- lb: 0x1 cc: 2

col

0: [ 2]

c1 04

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

tab 0, row 3, @0x1f33

tl: 19 fb: --H-FL-- lb: 0x1 cc: 2

col

0: [ 2]

c1 05

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

tab 0, row 4, @0x1f46

tl: 19 fb: --H-FL-- lb: 0x1 cc: 2

col

0: [ 2]

c1 06

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

tab 0, row 5, @0x1f59

tl: 19 fb: --H-FL-- lb: 0x1 cc: 2

col

0: [ 2]

c1 07

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

tab 0, row 6, @0x1f6c

tl: 19 fb: --H-FL-- lb: 0x1 cc: 2

col

0: [ 2]

c1 08

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

tab 0, row 7, @0x1f7f

tl: 19 fb: --H-FL-- lb: 0x1 cc: 2

col

0: [ 2]

c1 09

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

tab 0, row 8, @0x1f92

tl: 19 fb: --H-FL-- lb: 0x1 cc: 2

col

0: [ 2]

c1 0a

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

tab 0, row 9, @0x1fa5

tl: 19 fb: --H-FL-- lb: 0x1 cc: 2

col

0: [ 2]

c1 0b

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

end_of_block_dump

End dump data blocks tsn: 2 file#: 3 minblk 1954 maxblk 1955

SQL delete from tn where a =8 or

a = 7;

2 rows deleted.

SQL commit;

Commit complete.

SQL

alter system dump datafile 3 block 1955;

System altered.

删除2条记录后我们来看block中的变化

Block header dump:

0x00c007a3

Object id on Block? Y

seg/obj: 0x66b7

csc: 0x00.1891b8d

itc: 1

flg: O

typ: 1 - DATA

fsl: 0

fnx: 0x0 ver: 0x01

Itl

Xid

Uba

Flag

Lck

Scn/Fsc

0x01

xid:

0x0002.01a.000000e9

uba: 0x00800314.00d0.24

--U-

2

fsc 0x0022.01891b8f

data_block_dump

===============

tsiz: 0x1fb8

hsiz: 0x26

pbl: 0x0ba76c44

bdba: 0x00c007a3

flag=-----------

ntab=1

nrow=10

frre=-1

fsbo=0x26

fseo=0x1efa

avsp=0x1ed4

tosp=0x1efa

0xe:pti[0]

nrow=10

offs=0

0x12:pri[0]

offs=0x1efa

0x14:pri[1]

offs=0x1f0d

0x16:pri[2]

offs=0x1f20

0x18:pri[3]

offs=0x1f33

0x1a:pri[4]

offs=0x1f46

0x1c:pri[5]

offs=0x1f59

0x1e:pri[6]

offs=0x1f6c

--- 这里暂时没有发生变化

0x20:pri[7]

offs=0x1f7f

--- 这里暂时没有发生变化[/COLOR]

0x22:pri[8]

offs=0x1f92

0x24:pri[9]

offs=0x1fa5

block_row_dump:

tab 0, row 0, @0x1efa

tl: 19 fb: --H-FL-- lb: 0x0 cc: 2

col

0: [ 2]

c1 02

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

tab 0, row 1, @0x1f0d

tl: 19 fb: --H-FL-- lb: 0x0 cc: 2

col

0: [ 2]

c1 03

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

tab 0, row 2, @0x1f20

tl: 19 fb: --H-FL-- lb: 0x0 cc: 2

col

0: [ 2]

c1 04

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

tab 0, row 3, @0x1f33

tl: 19 fb: --H-FL-- lb: 0x0 cc: 2

col

0: [ 2]

c1 05

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

tab 0, row 4, @0x1f46

tl: 19 fb: --H-FL-- lb: 0x0 cc: 2

col

0: [ 2]

c1 06

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

tab 0, row 5, @0x1f59

tl: 19 fb: --H-FL-- lb: 0x0 cc: 2

col

0: [ 2]

c1 07

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

tab 0, row 6, @0x1f6c

tl: 2 fb: --HDFL-- lb: 0x1

----记录已经被删除

tab 0, row 7, @0x1f7f

tl: 2 fb: --HDFL-- lb: 0x1

----记录已经被删除[/COLOR]

tab 0, row 8, @0x1f92

tl: 19 fb: --H-FL-- lb: 0x0 cc: 2

col

0: [ 2]

c1 0a

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

tab 0, row 9, @0x1fa5

tl: 19 fb: --H-FL-- lb: 0x0 cc: 2

col

0: [ 2]

c1 0b

col

1: [12]

77 77 77 65 65 65 72 72 72 74 74 74

end_of_block_dump

End dump data blocks tsn: 2 file#: 3 minblk 1955 maxblk 1955

SQL

insert into tn values(19,'q');

1 row created.

SQL commit;

Commit complete.

SQL

alter system dump datafile 3 block 1955;

System altered.

插入一条记录,我们再看

Block header dump:

0x00c007a3

Object id on Block? Y

seg/obj: 0x66b7

csc: 0x00.1891b90

itc: 1

flg: O

typ: 1 - DATA

fsl: 0

fnx: 0x0 ver: 0x01

Itl

Xid

Uba

Flag

Lck

Scn/Fsc

0x01

xid:

0x0003.054.000000e8

uba: 0x00800da8.00d9.19

--U-

1

fsc 0x0000.01891b91

data_block_dump

===============

tsiz: 0x1fb8

hsiz: 0x28

pbl: 0x0ba76c44

bdba: 0x00c007a3

flag=-----------

ntab=1

nrow=11

frre=6

fsbo=0x28

fseo=0x1ef2

avsp=0x1eef

tosp=0x1eef

0xe:pti[0]

nrow=11

offs=0

0x12:pri[0]

offs=0x1efa

0x14:pri[1]

offs=0x1f0d

0x16:pri[2]

offs=0x1f20

0x18:pri[3]

offs=0x1f33

0x1a:pri[4]

offs=0x1f46

0x1c:pri[5]

offs=0x1f59

0x1e:pri[6]

sfll=7

----被删除

0x20:pri[7]

sfll=-1

------被删除

0x22:pri[8]

offs=0x1f

 
 
 
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