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 – UNLIMITEDEXTENT 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 displayedEXTENT 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 V8Map Extent:==> dba: dba of extent==> length: number of blocks in extentFREE 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 listsSegment List:==> flg: flag USED or UNUSED the free list==> lhd: head of free list==> ltl: tail of free list
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