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Title: 17.Data segment header block(with freelist groups)  •  Size: 235273  •  Last Modified: Thu, 04 Feb 2010 15:48:32 GMT
17 DATA SEGMENT HEADER WITH FREE LIST BLKS - UNLIMITED
 
  0 1 2 3 4 5 6 7 8 9 A B C D E F   Start dump data blocks tsn: 19 file#: 18 minblk 49 maxblk 49
00 111 022 003 004 31 00 80 045 11 8F 95 00 00 006 027 048   buffer tsn: 19 rdba: 0x04800031 (18/49)
10 61 299 00 0010 00 00 00 0011 00 00 00 0012 00 00 00 0013   HEADER scn: 0x0000.00958f11 seq: 0x02 flg: 0x04 tail: 0x8f111102
20 00 00 00 0014 02 00 00 0015 0C 00 00 0016 20 0417 00 00   frmt: 0x02 chkval: 0x2961 type: 0x11=DATA SEGMENT HEADER WITH
30 01 00 00 0018 05 00 00 0019 08 00 00 0020 3E 00 80 0421   HWM Extent Control Header FREE LIST BLKS - UNLIMITED
40 00 00 00 0022 01 00 00 0023 00 00 00 0024 09 00 00 0025   -----------------------------------------------------------------
50 00 00 00 00 00 00 00 00 00 00 00 00 02 00 00 0026   Map Header Extent Header:: spare1: 0 spare2: 0 #extents: 2 #blocks: 12
60 00 00 00 0027 C5 7A 00 0028 00 00 00 4029 35 00 80 0430   last map 0x00000000 #maps: 0 offset: 1056
70 04 00 00 0031 39 00 80 0432 08 00 00 0033 00 00 00 00   Extent Map Highwater:: 0x0480003e ext#: 1 blk#: 5 ext size: 8
80 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   #blocks in seg. hdr's freelists: 0
90 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   #blocks below: 9
A0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   mapblk 0x00000000 offset: 1
B0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   Unlocked
C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   Map Header:: next 0x00000000 #extents: 2 obj#: 31429 flag: 0x40000000
D0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   Extent Map
E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   -----------------------------------------------------------------
F0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   0x04800035 length: 4
100 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   0x04800039 length: 8
110 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  
120 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   nfl = 2, nfb = 4 typ = 1 nxf = 0 ccnt = 0
130 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   SEG LST:: flg: UNUSED lhd: 0x00000000 ltl: 0x00000000
140 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   End dump data blocks tsn: 19 file#: 18 minblk 49 maxblk 49
150 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
160 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
170 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
180 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
190 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
1A0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
1B0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
1C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
1D0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
1E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
1F0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
200 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
210 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
220 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
230 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
240 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
250 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
260 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
270 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
280 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
290 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
2A0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
2B0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
2C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
2D0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
2E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
2F0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
300 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
310 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
320 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
330 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
340 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
350 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
360 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
370 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
380 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
390 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
3A0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
3B0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
3C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
3D0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
3E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
3F0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
400 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
410 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
420 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
430 00 00 00 00 0034 0035 02 0036 04 0037 0138 00 0039 00 00 00    
440 00 00 00 00 00 00 00 0040 00 00 00 0041 00 00 00 0042   Freelists  
450 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
460 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
470 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
480 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
490 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
4A0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
4B0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
4C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
4D0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
4E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
4F0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
500 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
510 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
520 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
530 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
540 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
550 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
560 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
570 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
580 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
590 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
5A0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
5B0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
5C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
5D0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
5E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
5F0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
600 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
610 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
620 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
630 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
640 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
650 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
660 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
670 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
680 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
690 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
6A0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
6B0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
6C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
6D0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
6E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
6F0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
700 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
710 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
720 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
730 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
740 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
750 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
760 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
770 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
780 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
790 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
7A0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
7B0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
7C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
7D0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
7E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    
7F0 00 00 00 00 00 00 00 00 00 00 00 00 02 11 11 8F43    
 
SQL>create table TEST.table1  
(OWNER VARCHAR2(30) not null,  
OBJECT_NAME VARCHAR2(30) not null,  
SUBOBJECT_NAME VARCHAR2(30),  
OBJECT_ID NUMBER not null,  
DATA_OBJECT_ID NUMBER,  
OBJECT_TYPE VARCHAR2(18),  
CREATED DATE not null,  
LAST_DDL_TIME DATE not null,  
TIMESTAMP VARCHAR2(19),  
STATUS VARCHAR2(7),  
TEMPORARY VARCHAR2(1),  
GENERATED VARCHAR2(1),  
SECONDARY VARCHAR2(1)  
)  
storage  
(  
freelists 2  
freelist groups 3  
);  
SQL>insert into table1 select * from all_objects where rownum<100;  
SQL>commit;  
SQL>select header_file, header_block from dba_segments  
where owner='TEST' and segment_name='TABLE1';  
 
HEADER_FILE   HEADER_BLOCK        
18 49  
 
SQL> alter system dump datafile 18 block 49;  
SQL> alter system checkpoint;  

1
Block types. type:0x11
2
The format of the cache header was changed for Oracle8. Under Oracle8 and 9, the value is always 2. Previously, it was 1.
frmt:0x02
3
spare1
4
spare2
5
The tablespace relative database block address (RDBA). This is constructed from the tablespace relative file
number (10 bits), and the block number of the data block within that file (22 bits).
RDBA:0x04800031
6
The SCN at which the block was last changed. The low-order 4 bytes are called the SCN base, and the high-order 2 bytes are called the SCN wrap.
scn: 0x0000.00958F11
7
A sequence number incremented for each change to a block at the same SCN. If the sequence number wraps, a new SCN must be allocated. The value 0xff is reserved. When present it indicates that the block has been marked as corrupt by Oracle.
seq:0x02

8
Flag.
1 - virgin block
2 - last change to the block was for a cleanout operation
4 - checksum value is set
8 - temporary data
flg:0x04
9
An optional checksum of the block contents. When a block is written, the checksum is either cleared or set depending on the setting of the
db_block_checksum parameter. When a block is read, the checksum is verified if present and if the parameter is set to TRUE. Checksums are
always calculated and checked for blocks in the SYSTEM tablespace. The checksum is the XOR of all the other 2-byte pairs in the block. Thus
when a block with a checksum is checked, the XOR of all the 2-byte words in the block should be 0.
chkval:0x2961
10
spare3
11
spare1
12
spare2
13
RDBA of the last block of the extent map: 0x00000000
14
Number of maps.
#maps: 0

15
Number of extents.
#extents:2
16
Number of blocks.
#blocks:12

17
Freelists start offset.
offset: 1056

18
High water mark (HWM).
Highwater: extent no.
ext#: 1
19
High water mark (HWM).
Highwater: block no.
blk#: 5

20
High water mark (HWM).
Highwater: extent size.
size:8
21
High water mark (HWM) is the pointer to the DBA of the last block to receive inserts. Blocks below this mark are maintained on free lists.
Blocks in extents above this mark have been allocated to the segment but haven't been used yet. Blocks above the HWM are available for
SQL*Loader direct-load operations, parallel DML, and for inserts after the free list has been exhausted and the HWM has been moved.
Highwater: RDBA: 0x0480003E => file- 18 block- 62
22
Map block RDBA. mapblk: 0x0
23
Offset:1
24
#blocks in seg. hdr's freelists:0
25
#blocks below:9
26
Map Header.The map header simply contains DBA information of the next block containing extent map information.
Number of extents in extent map.
#extents:2
27
Contains DBA information of the next block containing extent map information.
Map Header: next 0x:00000000
28
Map Header: obj#:31429
29
Map Header: flag: 0x:40000000
30
Beginning RDBA :
RDBA (extent#): 0x04800035
31
Number of blocks associated with the extent.
len : 4
32
RDBA (extent#): 0x04800039
33
len : 8
34
Freelists.
35
Number of transaction frelists.
nxf:0
36
Number of segment freelists.
nfl: 2
37
Number of freelist blocks.
nfb:1
38
typ = 1
39
flg: UNUSED
40
ccnt = 0
41
Segment freelist: first block.
lhd: 0x00000000

42
Segment freelist: last block.
ltl: 0x00000000
43
Tail is comprised of the low-order two bytes of the SCN base followed by the block type and the sequence number. The consistency of the
header and tail is checked whenever a block is read. This detects most block corruptions, in particular split blocks from hot backups.
tail:0x8F111102