[20180604]在記憶體修改資料(bbed).txt

[20180604]在記憶體修改資料(bbed).txt

--//以前曾經做過在記憶體修改資料,透過oradebug poke命令修改記憶體資訊,相關連結：
--//http://blog.itpub.net/267265/viewspace-2124466/=>[20160904]在記憶體修改資料.txt

--//今天測試看看是否透過bbed修改資料資訊的情況.使用asmm,這樣/dev/shm可以看到一個一個檔案。

1.環境:
SCOTT@book> @ ver1
PORT_STRING                    VERSION        BANNER
------------------------------ -------------- --------------------------------------------------------------------------------
x86_64/Linux 2.4.xx            11.2.0.4.0     Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

2.建立測試:

create table t1 (id number,name varchar2(20));
insert into t1 values (1,'AAAAAAAAAAB');
commit ;

SCOTT@book> select rowid,t1.* from t1;
ROWID                      ID NAME
------------------ ---------- --------------------
AAAWQKAAEAAAAJcAAA          1 AAAAAAAAAAB

SCOTT@book> @ &r/rowid AAAWQKAAEAAAAJcAAA
    OBJECT       FILE      BLOCK        ROW ROWID_DBA            DBA                  TEXT
---------- ---------- ---------- ---------- -------------------- -------------------- ----------------------------------------
     91146          4        604          0  0x100025C           4,604                alter system dump datafile 4 block 604 ;

SYS@book> create pfile='/tmp/@.ora' from spfile;
File created.

--//修改/tmp/book.ora引數,加入
*.memory_target=5120M
*.memory_max_target=5120M
--//注:注意檢查use_large_pages引數,我的設定*.use_large_pages='ONLY',無法啟動,報
SYS@book> startup pfile=/tmp/book.ora
ORA-27125: unable to create shared memory segment

--//使用引數/tmp/book.ora引數啟動資料庫,這樣採用asmm方式.
SYS@book> startup pfile=/tmp/book.ora
ORACLE instance started.
Total System Global Area 1068994560 bytes
Fixed Size                  2259960 bytes
Variable Size             423625736 bytes
Database Buffers          637534208 bytes
Redo Buffers                5574656 bytes
Database mounted.
Database opened.

# ls -l /dev/shm/ora_book_*|wc

--//載入對應資料塊到記憶體:
SCOTT@book> select rowid,t1.* from t1;
ROWID                      ID NAME
------------------ ---------- --------------------
AAAWQKAAEAAAAJcAAA          1 AAAAAAAAAAB

SYS@book> @ &r/bh 4 604
HLADDR              DBARFIL     DBABLK      CLASS CLASS_TYPE         STATE             TCH CR_SCN_BAS CR_SCN_WRP CR_UBA_FIL CR_UBA_BLK CR_UBA_SEQ BA               OBJECT_NAME
---------------- ---------- ---------- ---------- ------------------ ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------------- --------------------
000000009DFCB238          4        604          1 data block         xcur                1          0          0          0          0          0 0000000081C14000 T1

3.在記憶體修改資料:
# strings -f -t d /dev/shm/ora_book_* | grep AAAAAAAAAAB
/dev/shm/ora_book_265158658_132:   90097 AAAAAAAAAAB
/dev/shm/ora_book_265158658_132: 3055545        3*AC60AAABAAAAAAAAAAAAAAAAAAAAAAB6UEsFBgAAAAABAAEALwAAABEXAAAAAA==

--//90097/8192 = 10.99816894531250000000
--//確定字串AAAAAAAAAAB在那個檔案.可以確定/dev/shm/ora_book_265158658_132.因為僅僅插入1條,應該在塊的底部.

4.使用bbed修改:
BBED> set filename '/dev/shm/ora_book_265158658_132'
        FILENAME        /dev/shm/ora_book_265158658_132

BBED> set blocksize 8192
        BLOCKSIZE       8192

--//注意一定要設定這個引數.不然看到的塊大小是512
BBED> show
        FILE#           0
        BLOCK#          1
        OFFSET          0
        DBA             0x00000000 (0 0,1)
        FILENAME        /dev/shm/ora_book_265158658_132
        BIFILE          bifile.bbd
        LISTFILE        /home/oracle/bbed/filelist.txt
        BLOCKSIZE       512
        MODE            Edit
        EDIT            Unrecoverable
        IBASE           Dec
        OBASE           Dec
        WIDTH           160
        COUNT           64
        LOGFILE         log.bbd
        SPOOL           Yes

BBED> set block 11
        BLOCK#          11
--//因為這個記憶體檔案的第一塊非檔案頭.所以block=11.

BBED> x /rnc *kdbr[0]
rowdata[0]                                  @8170
----------
flag@8170: 0x2c (KDRHFL, KDRHFF, KDRHFH)
lock@8171: 0x01
cols@8172:    2

col    0[2] @8173: 1
col   1[11] @8176: AAAAAAAAAAB

--//確定偏移量:
BBED> dump offset 8176
File: /dev/shm/ora_book_265158658_132 (0)
Block: 11                                                   Offsets: 8176 to 8191 Dba:0x00000000
--------------------------------------------------------------------------------------------------
0b414141 41414141 41414142 0106a09c
<64 bytes per line>

BBED> modify /c 'ABCD' offset 8177
Warning: contents of previous BIFILE will be lost. Proceed? (Y/N) y
File: /dev/shm/ora_book_265158658_132 (0)
Block: 11                                                   Offsets: 8177 to 8191 Dba:0x00000000
--------------------------------------------------------------------------------------------------
41424344 41414141 41414201 06a09c

--//再次查詢看看.
SYS@book> select rowid,t1.* from scott.t1;
ROWID                      ID NAME
------------------ ---------- --------------------
AAAWQKAAEAAAAJcAAA          1 ABCDAAAAAAB

--//注:我並沒有做檢查和,sum apply.
--//我已經透過記憶體篡改了資訊.

SYS@book> alter system flush BUFFER_CACHE;
System altered.

SYS@book> select rowid,t1.* from scott.t1;
ROWID                      ID NAME
------------------ ---------- --------------------
AAAWQKAAEAAAAJcAAA          1 AAAAAAAAAAB

--//現在有正常顯示回來.