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 FreeElists: 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 Withnin Extent
==> Ext size: HWM EXTENT SIZE (IN Blocks)
==> #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 With 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: 0x400000000x02000003 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 buy or unused the free list
==> lhd: Head of free list
==> LTL: TAIL OF Free List
