【摘要】 数据库管理系统中的查询优化处理一直回避处理查询定义中函数运算的优化问题，而在异构数据源集成系统、数据仓库系统和ＷＷＷ数据库中，大部分的用户查询都涉及到复杂的函数运算，因此，有必要研究带函数的关系操作的优化技术．本文定义了６种基本的带函数的关系操作，分析了这些操作的变换规则，并给出了一些查询优化策略．更多还原

【Abstract】 Query optimization implement of DBMS always avoids dealing with the user defined functions in query language. But in integrated heterogeneous data sources systems, data warehouse systems and WWW databases, most of queries involve complex user defined functions. So it is necessary to study the optimization of relational operations combined with user defined functions. This paper defines 6 basic operations combining user defined functions with relational operations, analyzes their transformation rule and gives some query optimization policies.更多还原