关于DBA(BLOCK ADDRESS)换算方法-白红宇

关于DBA的换算问题，我们知道了

10bit的file number，每个对象最多有1022个文件（2个文件预留）

22bit的block number，每个文件最多有4M个BLOCK

及DBA中高10位是文件号，第22位是块号，一般我们使用dbms_utility进行转换，但是

有了算法就可以模拟一个换算的C语言小程序，利用C语言位域结构体

其实我们只要加权相加即可：

#include

#define dn data->d

struct db_addr

{

unsigned d1:1;

unsigned d2:1;

unsigned d3:1;

unsigned d4:1;

unsigned d5:1;

unsigned d6:1;

unsigned d7:1;

unsigned d8:1;

unsigned d9:1;

unsigned d10:1;

unsigned d11:1;

unsigned d12:1;

unsigned d13:1;

unsigned d14:1;

unsigned d15:1;

unsigned d16:1;

unsigned d17:1;

unsigned d18:1;

unsigned d19:1;

unsigned d20:1;

unsigned d21:1;

unsigned d22:1;

unsigned d23:1;

unsigned d24:1;

unsigned d25:1;

unsigned d26:1;

unsigned d27:1;

unsigned d28:1;

unsigned d29:1;

unsigned d30:1;

unsigned d31:1;

unsigned d32:1;

};

void main ()

{

long dba,block1,block2,block3,block4,block5,file1,file2;

long blocksum,filesum;

struct db_addr *data;

printf("please input X dba!\n");

scanf("%x",&dba);

data=&dba;

block1=data->d1+data->d2*2+data->d3*pow(2,2)+data->d4*pow(2,3)+data->d5*pow(2,4);

// printf("%d",data->d1);

block2=data->d6*pow(2,5)+data->d7*pow(2,6)+data->d8*pow(2,7)+data->d9*pow(2,8)+data->d10*pow(2,9);

block3=data->d11*pow(2,10)+data->d12*pow(2,11)+data->d13*pow(2,12)+data->d14*pow(2,13)+data->d15*pow(2,14);

block4=data->d16*pow(2,15)+data->d17*pow(2,17)+data->d18*pow(2,17)+data->d19*pow(2,18)+data->d20*pow(2,19);

block5=data->d21*pow(2,20)+data->d22*pow(2,21);

blocksum=block1+block2+block3+block4+block5;

file1=data->d23*pow(2,0)+data->d24*pow(2,1)+data->d25*pow(2,2)+data->d26*pow(2,3)+data->d27*pow(2,4);

file2=data->d28*pow(2,5)+data->d29*pow(2,6)+data->d30*pow(2,7)+data->d31*pow(2,8)+data->d32*pow(2,9);

filesum=file1+file2;

printf("file id is:%ld\nblocks id is :%ld\n",filesum,blocksum);

}

如果我们使用程序换算

2c000d3

如下：

please input X dba!

2c000d3

file id is:11

blocks id is :211

实际和dbms_utility得到的是相同的。

SQL> select to_number('2c000d3','xxxxxxxxxxxxxx') from dual;

TO_NUMBER('2C000D3','XXXXXXXXX

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

46137555

SQL> select dbms_utility.data_block_address_file(46137555),

2 dbms_utility.data_block_address_block(46137555) from dual;

DBMS_UTILITY.DATA_BLOCK_ADDRES DBMS_UTILITY.DATA_BLOCK_ADDRES

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

11 211