#blocks in seg. hdr's freelists: 0
#blocks below: 245
mapblk 0x00000000 offset: 16
Unlocked
--------------------------------------------------------
Low HighWater Mark :
Highwater:: 0x010011f5 ext#: 16 blk#: 117 ext size: 128
#blocks in seg. hdr's freelists: 0
#blocks below: 245
mapblk 0x00000000 offset: 16
Level 1 BMB for High HWM block: 0x01001181
Level 1 BMB for Low HWM block: 0x01001181
--------------------------------------------------------
Segment Type: 1 nl2: 1 blksz: 8192 fbsz: 0
L2 Array start offset: 0x00001434
First Level 3 BMB: 0x00000000
L2 Hint for inserts: 0x010001d1
Last Level 1 BMB: 0x01001181
Last Level II BMB: 0x010001d1
Last Level III BMB: 0x00000000
Map Header:: next 0x00000000 #extents: 17 obj#: 23300 flag: 0x10000000
Inc # 0
Extent Map
################
做TRUNCATE操作然后DUMP段头
BYS@ bys3>truncate table test13;Table truncated.
BYS@ bys3>alter system checkpoint;
System altered.
BYS@ bys3>alter system dump datafile 4 block 466;
System altered.
#########################
Extent Header:: spare1: 0 spare2: 0 #extents: 1 #blocks: 8
last map 0x00000000 #maps: 0 offset: 2716
Highwater:: 0x010001d3 ext#: 0 blk#: 3 ext size: 8
#blocks below: 0
mapblk 0x00000000 offset: 0
Disk Lock:: Locked by xid: 0x0002.019.00001354
--------------------------------------------------------
Low HighWater Mark :
Highwater:: 0x010001d3 ext#: 0 blk#: 3 ext size: 8
#blocks in seg. hdr's freelists: 0
#blocks below: 0
mapblk 0x00000000 offset: 0
Level 1 BMB for High HWM block: 0x010001d0
Level 1 BMB for Low HWM block: 0x010001d0
--------------------------------------------------------
Segment Type: 1 nl2: 1 blksz: 8192 fbsz: 0
L2 Array start offset: 0x00001434
First Level 3 BMB: 0x00000000
L2 Hint for inserts: 0x010001d1
Last Level 1 BMB: 0x010001d0
Last Level II BMB: 0x010001d1
Last Level III BMB: 0x00000000
Map Header:: next 0x00000000 #extents: 1 obj#: 23304 flag: 0x10000000
Inc # 0
Extent Map
-----------------------------------------------------------------
0x010001d0 length: 8
Auxillary Map
--------------------------------------------------------
Extent 0 : L1 dba: 0x010001d0 Data dba: 0x010001d3
--------------------------------------------------------
Second Level Bitmap block DBAs
--------------------------------------------------------
DBA 1: 0x010001d1