BASE的计算方法为：
对于ASSM：76+（itc-1) * 24= 52 + itc * 24
对于MSSM：68+（itc-1) * 24= 44 + itc * 24

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1. gyj@ZMDB> select * from v$type_size where component in ('KCB','KTB');

3. COMPONEN TYPE DESCRIPTION TYPE_SIZE

4. -------- -------- -------------------------------- ----------

5. KCB KCBH BLOCK COMMON HEADER 20

6. KTB KTBIT TRANSACTION VARIABLE HEADER 24

7. KTB KTBBH TRANSACTION FIXED HEADER 48

8. KTB KTBBH_BS TRANSACTION BLOCK BITMAP SEGMENT 8

1、我们先对ASSM做测试

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1. gyj@ZMDB> select * from v$version;

3. BANNER

4. --------------------------------------------------------------------------------

5. Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production

7. gyj@ZMDB> create tablespace assm datafile '/u01/app/oracle/oradata/zmdb/assm01.dbf' size 50M;

9. Tablespace created.

11. gyj@ZMDB> create table gyj_t5(id int,name varchar2(100)) tablespace assm;

13. Table created.

15. gyj@ZMDB> insert into gyj_t5 values(1,'AAAAA');

17. 1 row created.

19. gyj@ZMDB> insert into gyj_t5 values(2,'BBBBB');

21. 1 row created.

23. gyj@ZMDB> insert into gyj_t5 values(3,'CCCCC');

25. 1 row created.

27. gyj@ZMDB> COMMIT;

29. Commit complete.

31. gyj@ZMDB> alter system flush buffer_cache;

33. System altered.

35. gyj@ZMDB> select dbms_rowid.rowid_relative_fno(rowid) file#,dbms_rowid.rowid_block_number(rowid) block#,id,name from gyj_t5;

37.      FILE# BLOCK# ID NAME

38. ---------- ---------- ---------- ----------

39.         10 135 1 AAAAA

40.         10 135 2 BBBBB

41.         10 135 3 CCCCC

44. BBED> set file 10 block 135

45.         FILE# 10

46.         BLOCK# 135

48. BBED> p kdbr[0]

49. sb2 kdbr[0] @118 8076

51. BBED> p *kdbr[0]

52. rowdata[24]

53. -----------

54. ub1 rowdata[24] @8176 0x2c

56. BBED> x /rnc

57. rowdata[24] @8176 

58. -----------

59. flag@8176: 0x2c (KDRHFL, KDRHFF, KDRHFH)

60. lock@8177: 0x01

61. cols@8178: 2

63. col 0[2] @8179: 1 

64. col 1[5] @8182: AAAAA

66. BBED> p ktbbhict

67. sb2 ktbbhict @36 2

69. 8176-8076=76+（itc-1) * 24= 76+（2-1）* 24=100

2、我们对MSSM做测试

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1. gyj@ZMDB> create tablespace mssm datafile '/u01/app/oracle/oradata/zmdb/mssm01.dbf' size 50M segment space management manual;

3. Tablespace created.

6. gyj@ZMDB> create table gyj_mssm(id int,name varchar2(100)) tablespace mssm;

8. Table created.

10. gyj@ZMDB> insert into gyj_mssm values(4,'DDDDD');

12. 1 row created.

14. gyj@ZMDB> insert into gyj_mssm values(5,'EEEEE');

16. 1 row created.

18. gyj@ZMDB> insert into gyj_mssm values(6,'FFFFF');

20. 1 row created.

22. gyj@ZMDB> commit;

24. Commit complete.

27. gyj@ZMDB> col name for a20

28. gyj@ZMDB> select dbms_rowid.rowid_relative_fno(rowid) file#,dbms_rowid.rowid_block_number(rowid) block#,id,name from gyj_mssm;

30.      FILE# BLOCK# ID NAME

31. ---------- ---------- ---------- --------------------

32.         11 129 4 DDDDD

33.         11 129 5 EEEEE

34.         11 129 6 FFFFF

36. BBED> set file 11 block 129

37.         FILE# 11

38.         BLOCK# 129

40. BBED> p kdbr[0]

41. sb2 kdbr[0] @110 8084

43. BBED> p *kdbr[0]

44. rowdata[24]

45. -----------

46. ub1 rowdata[24] @8176 0x2c

48. BBED> x /rnc

49. rowdata[24] @8176 

50. -----------

51. flag@8176: 0x2c (KDRHFL, KDRHFF, KDRHFH)

52. lock@8177: 0x01

53. cols@8178: 2

55. col 0[2] @8179: 4 

56. col 1[5] @8182: DDDDD

58. BBED> p ktbbhict

59. sb2 ktbbhict @36 2

61. 8176-8084=68+（itc-1) * 24=68+（2-1）*24=92

3、为什么ASSM要比MSSM多了8个字节

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1. ************MSSM

2. BBED> set file 11 block 129

3.         FILE# 11

4.         BLOCK# 129

6. BBED> map /v

7.  File: /u01/app/oracle/oradata/zmdb/mssm01.dbf (11)

8.  Block: 129 Dba:0x02c00081

9. ------------------------------------------------------------

10.  KTB Data Block (Table/Cluster)

12.  struct kcbh, 20 bytes @0 

13.     ub1 type_kcbh @0 

14.     ub1 frmt_kcbh @1 

15.     ub1 spare1_kcbh @2 

16.     ub1 spare2_kcbh @3 

17.     ub4 rdba_kcbh @4 

18.     ub4 bas_kcbh @8 

19.     ub2 wrp_kcbh @12 

20.     ub1 seq_kcbh @14 

21.     ub1 flg_kcbh @15 

22.     ub2 chkval_kcbh @16 

23.     ub2 spare3_kcbh @18 

25.  struct ktbbh, 72 bytes @20 

26.     ub1 ktbbhtyp @20 

27.     union ktbbhsid, 4 bytes @24 

28.     struct ktbbhcsc, 8 bytes @28 

29.     sb2 ktbbhict @36 

30.     ub1 ktbbhflg @38 

31.     ub1 ktbbhfsl @39 

32.     ub4 ktbbhfnx @40 

33.     struct ktbbhitl[2], 48 bytes @44 

35.  struct kdbh, 14 bytes @92 

36.     ub1 kdbhflag @92 

37.     sb1 kdbhntab @93 

38.     sb2 kdbhnrow @94 

39.     sb2 kdbhfrre @96 

40.     sb2 kdbhfsbo @98 

41.     sb2 kdbhfseo @100 

42.     sb2 kdbhavsp @102 

43.     sb2 kdbhtosp @104 

45.  struct kdbt[1], 4 bytes @106 

46.     sb2 kdbtoffs @106 

47.     sb2 kdbtnrow @108 

49.  sb2 kdbr[3] @110 

51.  ub1 freespace[8036] @116 

53.  ub1 rowdata[36] @8152 

55.  ub4 tailchk @8188

57. *****************ASSM

58. BBED> set file 10 block 135

59.         FILE# 10

60.         BLOCK# 135

62. File: /u01/app/oracle/oradata/zmdb/assm01.dbf (10)

63.  Block: 141 Dba:0x0280008d

64. ------------------------------------------------------------

65.  KTB Data Block (Table/Cluster)

67.  struct kcbh, 20 bytes @0 

68.     ub1 type_kcbh @0 

69.     ub1 frmt_kcbh @1 

70.     ub1 spare1_kcbh @2 

71.     ub1 spare2_kcbh @3 

72.     ub4 rdba_kcbh @4 

73.     ub4 bas_kcbh @8 

74.     ub2 wrp_kcbh @12 

75.     ub1 seq_kcbh @14 

76.     ub1 flg_kcbh @15 

77.     ub2 chkval_kcbh @16 

78.     ub2 spare3_kcbh @18 

80.  struct ktbbh, 72 bytes @20 

81.     ub1 ktbbhtyp @20 

82.     union ktbbhsid, 4 bytes @24 

83.     struct ktbbhcsc, 8 bytes @28 

84.     sb2 ktbbhict @36 

85.     ub1 ktbbhflg @38 

86.     ub1 ktbbhfsl @39 

87.     ub4 ktbbhfnx @40 

88.     struct ktbbhitl[2], 48 bytes @44 

90.  struct kdbh, 14 bytes @100 

91.     ub1 kdbhflag @100 

92.     sb1 kdbhntab @101 

93.     sb2 kdbhnrow @102 

94.     sb2 kdbhfrre @104 

95.     sb2 kdbhfsbo @106 

96.     sb2 kdbhfseo @108 

97.     sb2 kdbhavsp @110 

98.     sb2 kdbhtosp @112 

100.  struct kdbt[1], 4 bytes @114 

101.     sb2 kdbtoffs @114 

102.     sb2 kdbtnrow @116 

104.  sb2 kdbr[3] @118 

106.  ub1 freespace[8028] @124 

108.  ub1 rowdata[36] @8152 

110.  ub4 tailchk @8188

对比
-----MSSM
   struct ktbbhitl[2], 48 bytes            @44     

 struct kdbh, 14 bytes                     @92 

---ASSM   
   struct ktbbhitl[2], 48 bytes            @44     

 struct kdbh, 14 bytes                      @100 
 
@92---->@100  kdbh偏移量发生了变化，增加了8个byte。