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
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