Subject:  QREF: Blockdump - 8.x Data Segment Header in Oracle 
Creation Date:  25-APR-2000 


CACHE BLOCK:
See Note: 47132.1
     type: 0x10=DATA SEGMENT HEADER - UNLIMITED

EXTENT CONTROL:
  Extent Header:: spare1: 0      space2: 0      #extents: 13     #blocks: 1429  
                  last map  0x00000000  #maps: 0      offset: 4128  
      Highwater::  0x020004d0  ext#: 12     blk#: 275    ext size: 475   
  #blocks in seg. hdr's freelists: 5     
  #blocks below: 1229  
  mapblk  0x00000000  offset: 12    
                   Unlocked
==> spare1:   this field is no longer used (old inc#, now always 0)
==> space2:   this field is no longer used (old ts#, now always 0)
==> #extents: number of extents allocated to segment
==> #blocks:  number of blocks allocated to segment

==> last map: address of last extent map block
              0 if extent map is entirely in the segment header
==> #maps:    number of extent map block
==> offset:   offset to end of extent map

==> HWM dba:  address of block at highwater mark
==> ext#:     HWM extent number relative to segment
==> blk#:     HWM block number within extent
==> ext size: HWM extent size (in blocks)
==> #blocks in seg. hdr's freelists: number of blocks in seg. hdr's free list 
==> #blocks below: number of blocks below HWM
==> mapblk dba: dba of extent map block containing HWM extent
                is 0 if HWM is in the segment header
==> offset:   offset within extent map block
              is the ext# if HWM is in segment header

==> Locked by: if locked by a transaction, the xid is displayed


EXTENT MAP:
Map Header:: next  0x00000000  #extents: 13   obj#: 12141  flag: 0x40000000
   0x02000003  length: 4     
   0x02000007  length: 5     
   0x0200000c  length: 10    
   0x02000016  length: 15    
   0x02000025  length: 20    
   0x02000039  length: 30    
   0x02000057  length: 45    
   0x02000084  length: 65    
   0x020000c5  length: 95    
   0x02000124  length: 140   
   0x020001b0  length: 210   
   0x02000282  length: 315   
   0x020003bd  length: 475   
Map Header:
==> next dba: address of next extent map block
==> #extents: number of extents in this extent map block
==> obj#:     object id for this segment
==> flag:     Flag to mark the version of segment header
              is 2 if the segment header is V8
Map Extent:
==> dba:      dba of extent
==> length:   number of blocks in extent


FREE LIST:
  nfl = 1, nfb = 1 typ = 1 nxf = 0
  SEG LST:: flg: USED   lhd: 0x020004cb ltl: 0x020004cf 
Segment Header:
==> nfl: number of free lists/block
==> nfb: number of free list blocks + segment header
==> typ: block type 
==> nxf: number of transaction free lists
Segment List:
==> flg: flag USED or UNUSED the free list
==> lhd: head of free list
==> ltl: tail of free list