The SQL compiler USES query optimization to select the best performing access path for any given SQL statement (within a reasonable amount of time, of course).
SQL编译器使用查询优化来为任何给定的sql语句选择表现最好的访问路径(当然，这要在合理的时间内)。
In this paper, first the query technology on database is analysed, then two optimization methods are offered: the disintegration query and the best access path selection.
本文对数据库的查询技术进行分析，给出两种优化方法：分解查询和选择最优存取路径。
Path expression is one of the core components of most XML query languages. However, there are few researches on the issue of path expression optimization.
路径表达式是XML数据查询语言的核心部分，但是目前针对路径表达式本身进行优化的研究却相对较少。
In this paper, we make some researches on the XML query structure and analyze the optimization policy in logical optimization. How to optimize the path expression is discussed primarily in this paper.
本文介绍了XML查询的查询处理结构，分析了逻辑优化的常规策略，重点研究了如何针对路径表达式进行优化。
In this paper, we make some researches on the XML query structure and analyze the optimization policy in logical optimization. How to optimize the path expression is discussed primarily in this paper.
本文介绍了XML查询的查询处理结构，分析了逻辑优化的常规策略，重点研究了如何针对路径表达式进行优化。
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