Data Block Address

Source: Internet
Author: User
Tags dba
This is not a database administrator DBA, but rather a data block address, Dba:data. A Data Block Address (DBA) is the ' address ' of
Oracle Data block for access purposes
. ----from the discovery of Oracle Kernel technology Discover the
structure of the DBA: After 8, the first 10 bits in the DBA are the file numbers, followed by the block number.
DBA Transformation: After the dump file, some DBAs have the following conversion results, such as:
Rdba:0x010001c8 (4/456), and some DBAs do not have the converted results, such as logging high water dba:
 HWM Flag: HWM Set
      highwater::  0x010001d0  ext#: 0      blk#: 8      ext Size:8 in     
The example of the DBA, for example, convert:

Example of a DBA conversion: Http:// find the DBA for a given rowstart by getting the file and bloc K number of the row. Example:sql> SELECT 2 dbms_rowid.rowid_relative_fno (ROWID) rel_fno, 3 Dbms_rowid.rowid_block_number (ROWID) B
   Lockno, 4 empno, ename 5 from emp WHERE empno = 7369; Rel_fno blockno EMPNO ename----------------------------------------4 7369 SMITH No W, convert the file and block numbers to a DBA address:sql> variable dba varchar2 sql> exec:d ba: = dbms_utilit
Y.make_data_block_address (4, 20);
Pl/sql procedure successfully completed. sql> Print dba dba--------------------------------16777236 Convert A DBA back to file and block numbersexample:sql& Gt  Select Dbms_utility.data_block_address_block (16777236) "Block", 2 dbms_utility.data_block_address_file (16777236)
     "FILE" 3 from dual; Block FILE--------------------20 4 However, using the Dbms_Utility The DBA is not the same as the dump DBA, and the dump DBA can be computed using the square <span><span> of the conversion binary (given an example above), but Dbms_ Utility the computed DBA, using the conversion binary method, is clearly incorrect.

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