作者：晶晶小妹
我的实验目的是证明：不同的会话做插入操作会选择不同的L1块，即使一个L1块内只使用了一个块。
实验环境：
块大小：8K； 区大小1M； 实验表只包含一个区，为插入行；
步一：先通过查看dba_segments视图找到段头，通过段头找到L2块，转储L2块，查看一共有
几个L1，并记录其状态（L系列块的查找详见晶晶实验一，此处不再详述）
*** 2008-02-15 21:57:39.593
Start dump data blocks tsn: 12 file#: 10 minblk 139 maxblk 139
buffer tsn: 12 rdba: 0x0280008b (10/139)
scn: 0x0000.001e692e seq: 0x01 flg: 0x00 tail: 0x692e2101
frmt: 0x02 chkval: 0x0000 type: 0x21=SECOND LEVEL BITMAP BLOCK
Dump of Second Level Bitmap Block
number: 2 nfree: 2 ffree: 0 pdba: 0x0280008c
Inc #: 0 Objd: 52188
opcode:0
xid:
L1 Ranges :
--------------------------------------------------------
0x02800089 Free: 5 Inst: 1
0x0280008a Free: 5 Inst: 1
--------------------------------------------------------
End dump data blocks tsn: 12 file#: 10 minblk 139 maxblk 139
发现此L2块中，有两个L1。
转储其中一个L1块结果如下： DBA Ranges :
--------------------------------------------------------
0x02800089 Length: 64 Offset: 0
0:Metadata 1:Metadata 2:Metadata 3:Metadata
4:unformatted 5:unformatted 6:unformatted 7:unformatted
8:unformatted 9:unformatted 10:unformatted 11:unformatted
12:unformatted 13:unformatted 14:unformatted 15:unformatted
16:unformatted 17:unformatted 18:unformatted 19:unformatted
20:unformatted 21:unformatted 22:unformatted 23:unformatted
24:unformatted 25:unformatted 26:unformatted 27:unformatted
28:unformatted 29:unformatted 30:unformatted 31:unformatted
32:unformatted 33:unformatted 34:unformatted 35:unformatted
36:unformatted 37:unformatted 38:unformatted 39:unformatted
40:unformatted 41:unformatted 42:unformatted 43:unformatted
44:unformatted 45:unformatted 46:unformatted 47:unformatted
48:unformatted 49:unformatted 50:unformatted 51:unformatted
52:unformatted 53:unformatted 54:unformatted 55:unformatted
56:unformatted 57:unformatted 58:unformatted 59:unformatted
60:unformatted 61:unformatted 62:unformatted 63:unformatted
--------------------------------------------------------
End dump data blocks tsn: 12 file#: 10 minblk 137 maxblk 137
因目前表为空，L1的64个数据块都是未格式化的，参考段头的转储信息，得知高高水点和低
高水点都是141。
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