数据块转储及RDBA的转换

原文链接:

http://www.eygle.com/internal/How_to_dump_datablock.htm

Tuesday, 2004-08-31 17:51 Eygle

很多时候我们在进行进一步研究时需要转储(dump)Oracle的数据块,以研究其内容,Oracle提供了很好的方式,我们通过以下例子简单说明一下:

> >
> > > [oracle@jumper udump]$ sqlplus "/ as sysdba" >
> SQL*Plus: Release 9.2.0.3.0 - Production on Tue Aug 31 17:01:27 2004 >
> Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved. >
>
> Connected to: > Oracle9i Enterprise Edition Release 9.2.0.3.0 - Production > With the Partitioning, OLAP and Oracle Data Mining options > JServer Release 9.2.0.3.0 - Production >
> SQL> select rowid,deptno,dname,loc from scott.dept; >
> ROWID DEPTNO DNAME LOC > ------------------ ---------- -------------- ------------- > AAADZ7AABAAAGK6AAA 10 ACCOUNTING NEW YORK > AAADZ7AABAAAGK6AAB 20 RESEARCH DALLAS > AAADZ7AABAAAGK6AAC 30 SALES CHICAGO > AAADZ7AABAAAGK6AAD 40 OPERATIONS BOSTON >
> SQL> select file_id,block_id,blocks from dba_extents where segment_name='DEPT'; >
> FILE_ID BLOCK_ID BLOCKS > ---------- ---------- ---------- > 1 25273 8 >
>
> SQL> alter system dump datafile 1 block min 25273 block max 25274; >
> System altered. >
> SQL> ! > [oracle@jumper udump]$ ls -l > total 4 > -rw-r----- 1 oracle dba 3142 Aug 31 17:04 hsjf_ora_13674.trc > [oracle@jumper udump]$ more hsjf_ora_13674.trc > /opt/oracle/admin/hsjf/udump/hsjf_ora_13674.trc > Oracle9i Enterprise Edition Release 9.2.0.3.0 - Production > With the Partitioning, OLAP and Oracle Data Mining options > JServer Release 9.2.0.3.0 - Production > ORACLE_HOME = /opt/oracle/product/9.2.0 > System name: Linux > Node name: jumper.hurray.com.cn > Release: 2.4.18-14 > Version: #1 Wed Sep 4 13:35:50 EDT 2002 > Machine: i686 > Instance name: hsjf > Redo thread mounted by this instance: 1 > Oracle process number: 9 > Unix process pid: 13674, image: [email protected] (TNS V1-V3) >
> *** 2004-08-31 17:04:27.820 > *** SESSION ID:(8.3523) 2004-08-31 17:04:27.819 > Start dump data blocks tsn: 0 file#: 1 minblk 25273 maxblk 25274 > buffer tsn: 0 rdba: 0x004062b9 (1/25273) > scn: 0x0000.0057c70d seq: 0x01 flg: 0x04 tail: 0xc70d1001 > frmt: 0x02 chkval: 0x12e3 type: 0x10=DATA SEGMENT HEADER - UNLIMITED > Extent Control Header > ----------------------------------------------------------------- > Extent Header:: spare1: 0 spare2: 0 #extents: 1 #blocks: 7
> last map 0x00000000 #maps: 0 offset: 4128
> Highwater:: 0x004062bb ext#: 0 blk#: 1 ext size: 7
> #blocks in seg. hdr's freelists: 1
> #blocks below: 1
> mapblk 0x00000000 offset: 0
> Unlocked > Map Header:: next 0x00000000 #extents: 1 obj#: 13947 flag: 0x40000000 > Extent Map > ----------------------------------------------------------------- > 0x004062ba length: 7
>
> nfl = 1, nfb = 1 typ = 1 nxf = 0 ccnt = 1 > SEG LST:: flg: USED lhd: 0x004062ba ltl: 0x004062ba > buffer tsn: 0 rdba: 0x004062ba (1/25274) > scn: 0x0000.0131909b seq: 0x07 flg: 0x04 tail: 0x909b0607 > frmt: 0x02 chkval: 0xa8e7 type: 0x06=trans data > Block header dump: 0x004062ba > Object id on Block? Y > seg/obj: 0x367b csc: 0x00.131909a itc: 2 flg: O typ: 1 - DATA > fsl: 0 fnx: 0x0 ver: 0x01 >
> Itl Xid Uba Flag Lck Scn/Fsc > 0x01 0x0001.02a.000003f3 0x0080000b.0188.08 C--- 0 scn 0x0000.0057c70e > 0x02 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 >
> data_block_dump,data header at 0xadb505c > =============== > tsiz: 0x1fa0 > hsiz: 0x1a > pbl: 0x0adb505c > bdba: 0x004062ba > 76543210 > flag=-------- > ntab=1 > nrow=4 > frre=-1 > fsbo=0x1a > fseo=0x1f44 > avsp=0x1f2a > tosp=0x1f2a > 0xe:pti[0] nrow=4 offs=0 > 0x12:pri[0] offs=0x1f86 > 0x14:pri[1] offs=0x1f70 > 0x16:pri[2] offs=0x1f5c > 0x18:pri[3] offs=0x1f44 > block_row_dump: > tab 0, row 0, @0x1f86 > tl: 26 fb: --H-FL-- lb: 0x0 cc: 3 > col 0: [ 2] c1 0b > col 1: [10] 41 43 43 4f 55 4e 54 49 4e 47 > col 2: [ 8] 4e 45 57 20 59 4f 52 4b > tab 0, row 1, @0x1f70 > tl: 22 fb: --H-FL-- lb: 0x0 cc: 3 > col 0: [ 2] c1 15 > col 1: [ 8] 52 45 53 45 41 52 43 48 > col 2: [ 6] 44 41 4c 4c 41 53 > tab 0, row 2, @0x1f5c > tl: 20 fb: --H-FL-- lb: 0x0 cc: 3 > col 0: [ 2] c1 1f > col 1: [ 5] 53 41 4c 45 53 > col 2: [ 7] 43 48 49 43 41 47 4f > tab 0, row 3, @0x1f44 > tl: 24 fb: --H-FL-- lb: 0x0 cc: 3 > col 0: [ 2] c1 29 > col 1: [10] 4f 50 45 52 41 54 49 4f 4e 53 > col 2: [ 6] 42 4f 53 54 4f 4e > end_of_block_dump > End dump data blocks tsn: 0 file#: 1 minblk 25273 maxblk 25274 > >
> > >

很多人经常提出的一个问题是,rdba是如何转换的?

rdba: 0x004062ba (1/25274)

我们通过这个例子介绍一下.

rdba从Oracle6->Oracle7->Oracle8发生了三次改变:

在Oracle6中,rdba由6位2进制数表示,也就是说数据块最多只能有2^6=64个数据文件(去掉全0和全1, 实际上最多只能代表62个文件)

在Oracle7中,rdba中的文件号增加为10位,为了向后兼容,从Block号的高位拿出4位作为文件号的高位.这样从6->7的Rowid无需发生变化.

在Oracle8中,文件号仍然用10位表示,只是不再需要置换,为了向后兼容,同时引入了相对文件号(rfile#),所以从Oracle7到Oracle8,Rowid仍然无需发生变化.

举例说明如下:

在Oracle6中:
比如: file 8, block 56892
		26位block号==56892
      vv  vvvvvvvv  vvvvvvvv  vvvvvvvv
00100000  00000000  11011110  00111100 
^^^^^^
6位文件号==8


在Oracle7中:
比如:File 255, block 56892 

11111100 11000000  11011110  00111100
 F   C    C   0     D   E     3  C 
\_____/\___/\_______________________/ 
   |     |	     | 		
   |     |	Block = 0xDE3C = 56892    	
   \_____________	    		
         |  \ 		
         V   V    		      
        0011   111111 = 0xFF = 255 --注意这里高位和低位要置换才能得出正确的file#

在Oracle8中:
比如:File 255, block 56892 

11111100 11000000  11011110  00111100
 F   C    C   0     D   E     3  C 
\_____/\___/\_______________________/ 
   |     |	     | 		
   |     |	Block = 0xDE3C = 56892    	
   \_____________	    		
         |  \ 		
         V   V    		      
      0011 1111 0011 = 03F3 = 1011 --这就是相对文件号

对于我们测试中的例子:

rdba: 0x004062ba (1/25274)

也就是:0000 0000 0100 0000 0110 0010 1011 1010

前10位为rfile#: 0000 0000 01 = 1

后22位为Block#:00 0000 0110 0010 1011 1010 = 25274