RE: Will dump block make dirty block written to disk?
- From: "Christian Antognini" <Christian.Antognini@xxxxxxxxxxxx>
- To: <kamusis@xxxxxxxxx>
- Date: Sun, 12 Mar 2006 23:14:48 +0100
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
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