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关于Oracle调优中“建立索引”的补充

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Release： 2016-06-07 17:07:38
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关于Oracle调优中ldquo;建立索引rdquo;的补充

建立索引是很好地调优方法，可以大幅提高查询速度。

但是除了在每个字段上建立索引之外，还可以有如下的建立方法：

1. 建立查询条件的联合索引：

把查询条件中 某个表用到的全部字段 合在一起，建立一个索引，，可以提高查询效率

2. 建立查询结果的联合索引

把查询结果中 某个表被查出来的全部字段 合在一起，建立一个索引，可以提高查询效率

3.  建立基于多个字段上的unique索引

unique索引不一定仅仅由主键决定，如果多个字段联合起来能唯一确定一条数据，那么可以把它们联合起来建立一条索引

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