详细解析9i和10g的datafile header

我曾经在很久以前问过熊哥----9i、10g、11g的block的结构有何区别？熊哥回答我说8i、9i、10g、11g的block的结构没有任何区别，只是8i、9i、10g、11g的datafile header有些不同，所以对于ODU而言，只需要处理掉datafile header的不同就可以做到同时兼容8i、9i、10g和11g。

我当时没有细问有哪些具体的不同，原因很简单----因为我想自己先研究一下，实在不行了再问。

好了，我们现在来看一下9i和10g的datafile header的区别，这里是以9.2.0.6和10.2.0.4来举例说明。

9.2.0.6：

BBED> set file 1

FILE# 1

BBED> set block 1

BLOCK# 1

BBED> map /v

File: /dras11/oradata/astca/system01.dbf (1)

Block: 1 Dba:0x00400001

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

Data File Header

struct kcvfh, 608 bytes @0

struct kcvfhbfh, 20 bytes @0

struct kcvfhhdr, 76 bytes @20

ub4 kcvfhrdb @96

struct kcvfhcrs, 8 bytes @100

ub4 kcvfhcrt @108

ub4 kcvfhrlc @112

struct kcvfhrls, 8 bytes @116

ub4 kcvfhbti @124

struct kcvfhbsc, 8 bytes @128

ub2 kcvfhbth @136

ub2 kcvfhsta @138

struct kcvfhckp, 160 bytes @140

ub4 kcvfhcpc @300

ub4 kcvfhrts @304

ub4 kcvfhccc @308

struct kcvfhbcp, 160 bytes @312

ub4 kcvfhbhz @472

struct kcvfhxcd, 16 bytes @476

word kcvfhtsn @492

ub2 kcvfhtln @496

text kcvfhtnm[30] @498

ub4 kcvfhrfn @528

struct kcvfhrfs, 8 bytes @532

ub4 kcvfhrft @540

struct kcvfhafs, 8 bytes @544

ub4 kcvfhbbc @552

ub4 kcvfhncb @556

ub4 kcvfhmcb @560

ub4 kcvfhlcb @564

ub4 kcvfhbcs @568

ub2 kcvfhofb @572

ub2 kcvfhnfb @574

ub4 kcvfhprc @576

struct kcvfhprs, 8 bytes @580

struct kcvfhprfs, 8 bytes @588

ub4 kcvfhtrt @604

ub4 tailchk @8188

也就是说----对于9i的datafile header，只有608个bytes。

10.2.0.4：

BBED> set file 1

FILE# 1

BBED> set block 1

BLOCK# 1

BBED> map /v

File: /iprat02/ipratest/system01.dbf (1)

Block: 1 Dba:0x00400001

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

Data File Header

struct kcvfh, 676 bytes @0

struct kcvfhbfh, 20 bytes @0

struct kcvfhhdr, 76 bytes @20

ub4 kcvfhrdb @96

struct kcvfhcrs, 8 bytes @100

ub4 kcvfhcrt @108

ub4 kcvfhrlc @112

struct kcvfhrls, 8 bytes @116

ub4 kcvfhbti @124

struct kcvfhbsc, 8 bytes @128

ub2 kcvfhbth @136

ub2 kcvfhsta @138

struct kcvfhckp, 160 bytes @484

ub4 kcvfhcpc @140

ub4 kcvfhrts @144

ub4 kcvfhccc @148

struct kcvfhbcp, 160 bytes @152

ub4 kcvfhbhz @312

struct kcvfhxcd, 16 bytes @316

word kcvfhtsn @332

ub2 kcvfhtln @336

text kcvfhtnm[30] @338

ub4 kcvfhrfn @368

struct kcvfhrfs, 8 bytes @372

ub4 kcvfhrft @380

struct kcvfhafs, 8 bytes @384

ub4 kcvfhbbc @392

ub4 kcvfhncb @396

ub4 kcvfhmcb @400

ub4 kcvfhlcb @404

ub4 kcvfhbcs @408

ub2 kcvfhofb @412

ub2 kcvfhnfb @414

ub4 kcvfhprc @416

struct kcvfhprs, 8 bytes @420

struct kcvfhprfs, 8 bytes @428

ub4 kcvfhtrt @444

ub4 tailchk @8188

也就是说----对于10g的datafile header，有676个bytes。

我们可以从结果里很清晰的看到在9i里结构kcvfhckp的offset是140，而在10g里kcvfhckp的offset是484，也就是说oracle在10g里把结构kcvfhckp挪到了datafile header block的最末端。

换句话说，9i和10g的datafile header在结构kcvfhckp之前的位置都是一样的，但从kcvfhckp开始之后的位置就全部不一样了，注意，这里只是位置不一样，各结构的长度还是一样的。

好了，我们现在来详细解释datafile header的各个byte的含义，上文中我已经提到，9i和10g的datafile header中的各个结构只是位置发生了变化，并没有长度和结构本身的变化，所以这里我只需以10g的datafile header为例来详细解释各个byte的含义：

BBED> set offset 0

OFFSET 0

BBED> dump

File: /iprat02/ipratest/system01.dbf (1)

Block: 1 Offsets: 0 to 511 Dba:0x00400001

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

0ba20000 00400001 00000000 00000104 0bb20000 00000000 0a200100 5091aeb3

49505241 54455354 0000329d 0000f000 00002000 00010003 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

00400179 00000008 00000000 21a23e84 28144e35 00086983 0000000a 00000000

00000000 00000000 00002004 00000156 28144e27 00000155 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00065359 5354454d 00000000 00000000

00000000 00000000 00000000 00000000 00000001 00000000 00000000 00000000

00000000 00005480 00000000 00000000 00000000 00000000 00000000 000a000a

21a23e71 00000001 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 d0d59fee 000bd5c4 29797a28 00019268 000000c4 00000002 00100001

<32 bytes per line>

BBED> set offset 512

OFFSET 512

BBED> dump

File: /iprat02/ipratest/system01.dbf (1)

Block: 1 Offsets: 512 to 1023 Dba:0x00400001

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

02000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00060006 00060100 00000000 00000000 00000000 00400002 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

<32 bytes per line>

BBED> set offset 8000

OFFSET 8000

BBED> dump

File: /iprat02/ipratest/system01.dbf (1)

Block: 1 Offsets: 8000 to 8191 Dba:0x00400001

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

00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000b01

<32 bytes per line>

这里我们来以kcvfh的详细结构来解释上述dump结果中各个byte的详细含义，我这里只解释我知道的各个byte的含义：

BBED> p kcvfh

struct kcvfh, 676 bytes @0

struct kcvfhbfh, 20 bytes @0

ub1 type_kcbh @0 0x0b

ub1 frmt_kcbh @1 0xa2

ub1 spare1_kcbh @2 0x00

ub1 spare2_kcbh @3 0x00

ub4 rdba_kcbh @4 0x00400001

ub4 bas_kcbh @8 0x00000000

ub2 wrp_kcbh @12 0x0000

ub1 seq_kcbh @14 0x01

ub1 flg_kcbh @15 0x04 (KCBHFCKV)

ub2 chkval_kcbh @16 0x0bb2

ub2 spare3_kcbh @18 0x0000

struct kcvfhhdr, 76 bytes @20

ub4 kccfhswv @20 0x00000000

ub4 kccfhcvn @24 0x0a200100

ub4 kccfhdbi @28 0x5091aeb3

text kccfhdbn[0] @32 I

text kccfhdbn[1] @33 P

text kccfhdbn[2] @34 R

text kccfhdbn[3] @35 A

text kccfhdbn[4] @36 T

text kccfhdbn[5] @37 E

text kccfhdbn[6] @38 S

text kccfhdbn[7] @39 T

ub4 kccfhcsq @40 0x0000329d

ub4 kccfhfsz @44 0x0000f000

s_blkz kccfhbsz @48 0x00

ub2 kccfhfno @52 0x0001

ub2 kccfhtyp @54 0x0003

ub4 kccfhacid @56 0x00000000

ub4 kccfhcks @60 0x00000000

text kccfhtag[0] @64

text kccfhtag[1] @65

text kccfhtag[2] @66

text kccfhtag[3] @67

text kccfhtag[4] @68

text kccfhtag[5] @69

text kccfhtag[6] @70

text kccfhtag[7] @71

text kccfhtag[8] @72

text kccfhtag[9] @73

text kccfhtag[10] @74

text kccfhtag[11] @75

text kccfhtag[12] @76

text kccfhtag[13] @77

text kccfhtag[14] @78

text kccfhtag[15] @79

text kccfhtag[16] @80

text kccfhtag[17] @81

text kccfhtag[18] @82

text kccfhtag[19] @83

text kccfhtag[20] @84

text kccfhtag[21] @85

text kccfhtag[22] @86

text kccfhtag[23] @87

text kccfhtag[24] @88

text kccfhtag[25] @89

text kccfhtag[26] @90

text kccfhtag[27] @91

text kccfhtag[28] @92

text kccfhtag[29] @93

text kccfhtag[30] @94

text kccfhtag[31] @95

ub4 kcvfhrdb @96 0x00400179

struct kcvfhcrs, 8 bytes @100

ub4 kscnbas @100 0x00000008

ub2 kscnwrp @104 0x0000

ub4 kcvfhcrt @108 0x21a23e84

ub4 kcvfhrlc @112 0x28144e35

struct kcvfhrls, 8 bytes @116

ub4 kscnbas @116 0x00086983

ub2 kscnwrp @120 0x0000

ub4 kcvfhbti @124 0x00000000

struct kcvfhbsc, 8 bytes @128

ub4 kscnbas @128 0x00000000

ub2 kscnwrp @132 0x0000

ub2 kcvfhbth @136 0x0000

ub2 kcvfhsta @138 0x2004 (KCVFHOFZ)

struct kcvfhckp, 160 bytes @484

struct kcvcpscn, 8 bytes @484

ub4 kscnbas @484 0xd0d59fee

ub2 kscnwrp @488 0x000b

ub4 kcvcptim @492 0x29797a28

ub2 kcvcpthr @496 0x0001

union u, 12 bytes @500

struct kcvcprba, 12 bytes @500

ub4 kcrbaseq @500 0x000000c4

ub4 kcrbabno @504 0x00000002

ub2 kcrbabof @508 0x0010

ub1 kcvcpetb[0] @512 0x02

ub1 kcvcpetb[1] @513 0x00

......省略显示部分内容

ub1 kcvcpetb[127] @639 0x00

ub1 kcvcpetb[128] @640 0x00

ub4 kcvfhcpc @140 0x00000156

ub4 kcvfhrts @144 0x28144e27

ub4 kcvfhccc @148 0x00000155

struct kcvfhbcp, 160 bytes @152

struct kcvcpscn, 8 bytes @152

ub4 kscnbas @152 0x00000000

ub2 kscnwrp @156 0x0000

ub4 kcvcptim @160 0x00000000

ub2 kcvcpthr @164 0x0000

union u, 12 bytes @168

struct kcvcprba, 12 bytes @168

ub4 kcrbaseq @168 0x00000000

ub4 kcrbabno @172 0x00000000

ub2 kcrbabof @176 0x0000

ub1 kcvcpetb[0] @180 0x00

ub1 kcvcpetb[1] @181 0x00

......省略显示部分内容

ub1 kcvcpetb[127] @307 0x00

ub1 kcvcpetb[128] @308 0x00

ub4 kcvfhbhz @312 0x00000000

struct kcvfhxcd, 16 bytes @316

ub4 space_kcvmxcd[0] @316 0x00000000

ub4 space_kcvmxcd[1] @320 0x00000000

ub4 space_kcvmxcd[2] @324 0x00000000

ub4 space_kcvmxcd[3] @328 0x00000000

word kcvfhtsn @332 0

ub2 kcvfhtln @336 0x0006

text kcvfhtnm[0] @338 S

text kcvfhtnm[1] @339 Y

text kcvfhtnm[2] @340 S

text kcvfhtnm[3] @341 T

text kcvfhtnm[4] @342 E

text kcvfhtnm[5] @343 M

text kcvfhtnm[6] @344

text kcvfhtnm[7] @345

text kcvfhtnm[8] @346

text kcvfhtnm[9] @347

text kcvfhtnm[10] @348

text kcvfhtnm[11] @349

text kcvfhtnm[12] @350

text kcvfhtnm[13] @351

text kcvfhtnm[14] @352

text kcvfhtnm[15] @353

text kcvfhtnm[16] @354

text kcvfhtnm[17] @355

text kcvfhtnm[18] @356

text kcvfhtnm[19] @357

text kcvfhtnm[20] @358

text kcvfhtnm[21] @359

text kcvfhtnm[22] @360

text kcvfhtnm[23] @361

text kcvfhtnm[24] @362

text kcvfhtnm[25] @363

text kcvfhtnm[26] @364

text kcvfhtnm[27] @365

text kcvfhtnm[28] @366

text kcvfhtnm[29] @367

ub4 kcvfhrfn @368 0x00000001

struct kcvfhrfs, 8 bytes @372

ub4 kscnbas @372 0x00000000

ub2 kscnwrp @376 0x0000

ub4 kcvfhrft @380 0x00000000

struct kcvfhafs, 8 bytes @384

ub4 kscnbas @384 0x00000000

ub2 kscnwrp @388 0x0000

ub4 kcvfhbbc @392 0x00000000

ub4 kcvfhncb @396 0x00000000

ub4 kcvfhmcb @400 0x00000000

ub4 kcvfhlcb @404 0x00000000

ub4 kcvfhbcs @408 0x00000000

ub2 kcvfhofb @412 0x000a

ub2 kcvfhnfb @414 0x000a

ub4 kcvfhprc @416 0x21a23e71

struct kcvfhprs, 8 bytes @420

ub4 kscnbas @420 0x00000001

ub2 kscnwrp @424 0x0000

struct kcvfhprfs, 8 bytes @428

ub4 kscnbas @428 0x00000000

ub2 kscnwrp @432 0x0000

ub4 kcvfhtrt @444 0x00000000

第0个byte，如下图所示：