webtet 发表于 2018-9-26 07:30:17

Oracle索引分析与比较

SQL> select 'number',dump(1,16) from dual  2 union all select 'number',dump(2,16) from dual
  3 union all select 'number',dump(3,16) from dual;
  'NUMBE DUMP(1,16)
  ------ -----------------
  number Typ=2 Len=2: c1,2 (1)
  number Typ=2 Len=2: c1,3 (2)
  number Typ=2 Len=2: c1,4 (3)
  再对比一下反向以后的情况:
  SQL> select 'number',dump(reverse(1),16) from dual
  2 union all select 'number',dump(reverse(2),16) from dual
  3 union all select 'number',dump(reverse(3),16) from dual;
  'NUMBE DUMP(REVERSE(1),1
  ------ -----------------
  number Typ=2 Len=2: 2,c1 (1)
  number Typ=2 Len=2: 3,c1 (2)
  number Typ=2 Len=2: 4,c1 (3)

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