一种自底向上的静态语义查询优化算法

演绎数据库语义查询优化是运用数据库中的语义知识，即完整性约束条件，将用户提交的一种查询转换为能有效执行，并与原查询等价的查询的一种优化方法．至今在这一领域已有了许多的算法，但大多是基于自顶向下的查询计算模式．而本文提出的静态语义查询优化算法及其改进算法是在优化“并”和“连接”操作的过程中进行自底向上的查询计算，因此相对自顶向下的计算方式更有效地提高了查询执行效率．

Algorithm of Bottom-up Static Semantic Query Optimization

Semantic query optimization of deductive database is an optimization method, through semantic knowledge, namely integrity constraints in deductive databases, which turns queries that user casts into efficient and equivalent ones. Up to now, there are many algorithms in this field, but most of them are based on top-down evaluation strategy. In this paper, we present the algorithm of static semantic query optimization, which is based on bottom-up strategy in the process of optimization of union and join operations. Therefore, it makes query more efficiently comparing with top-down evaluation algorithms.