Kamus

>But, can anyone prove if that block is dirty, will
>DUMP action cause the DBWn to write this block
>into disk or not?

"prove" is big word... I'll limit myself to show you that in my case the dirty block is not written to disk.

SQL> CREATE TABLE t (n NUMBER) TABLESPACE test_8k;

SQL> INSERT INTO t VALUES (42);

SQL> COMMIT;

SQL> ALTER SYSTEM CHECKPOINT;

SQL> INSERT INTO t VALUES (666);

SQL> SELECT n,
  2         dump(n,16) n_hex,
  3         dbms_rowid.rowid_relative_fno(rowid) rfile_nr,
  4         dbms_rowid.rowid_block_number(rowid) block_nr,
  5         dbms_rowid.rowid_row_number(rowid) row_nr
  6  FROM t;

         N N_HEX                  RFILE_NR   BLOCK_NR     ROW_NR
---------- -------------------- ---------- ---------- ----------
        42 Typ=2 Len=2: c1,2b            9         10          0
       666 Typ=2 Len=3: c2,7,43          9         10          1

SQL> SELECT name FROM v$datafile WHERE rfile# = 9;

NAME
--------------------------------------------------------------------------
/u00/oradata/A1020/test_8k.dbf

SQL> ALTER SYSTEM DUMP DATAFILE '/u00/oradata/A1020/test_8k.dbf' BLOCK 10;


Now, to check the data in the file, you can either use a dump at OS level or BBED. Since BBED knows the format of the blocks, I'll use it... As you can see only a single row, the first one, is shown.

BBED> info
File#  Name                                                        Size(blks)
-----  ----                                                        ----------
     9  /u00/oradata/A1020/test_8k.dbf                                    1280
    11  /u00/oradata/A1020/test_8k_assm.dbf                               1280
    15  /u00/oradata/A1020/undotbs2.dbf                                  12800

BBED> set dba 9,10
        DBA             0x0240000a (37748746 9,10)

BBED> x /*r rowdata
rowdata[0]                                  @8182
----------
flag@8182: 0x2c (KDRHFL, KDRHFF, KDRHFH)
lock@8183: 0x01
cols@8184:    1

col    0[2] @8185:  0xc1  0x2b

tailchk                                     @8188
-------
BBED-00210: no row at this offset


In the trace file I have the following data (notice that only one row, the first one, is available).

block_row_dump:
tab 0, row 0, @0x1f9a
tl: 6 fb: --H-FL-- lb: 0x1  cc: 1
col  0: [ 2]  c1 2b
end_of_block_dump


Of course if I execute another "ALTER SYSTEM CHECKPOINT" I see the following output.

BBED> x /*r rowdata
rowdata[0]                                  @8175
----------
flag@8175: 0x2c (KDRHFL, KDRHFF, KDRHFH)
lock@8176: 0x02
cols@8177:    1

col    0[3] @8178:  0xc2  0x07  0x43

rowdata[7]                                  @8182
----------
flag@8182: 0x2c (KDRHFL, KDRHFF, KDRHFH)
lock@8183: 0x01
cols@8184:    1

col    0[2] @8185:  0xc1  0x2b

tailchk                                     @8188
-------
BBED-00210: no row at this offset



HTH
Chris