演绎数据库中语义查询的动态优化算法

A Dynamic Optimization Algorithm of Semantic Query in Deductive Database

演绎数据库的语义查询优化是利用数据库中的完整性约束,将用户提交的查询转换为与原查询等价且执行效率更高的查询规则。该文提出的动态语义优化算法在查询计算过程中动态约去存在的空展开式,使得查询时间开销的节省可用所除去的空展开式规模大小衡量,较适用于含有大量空展开式的演绎数据库。

Semantic query optimization in deductive database is based on integrity constraints to convert user＇s query to another one that is the equivalence to the former and more efficient. This paper proposes the dynamic query optimization, which deletes the null expansions in the process of the query so that the cost can be simply measured by the scale of deleted these null expansions. In the field such as deductive database that has more null expansions, the dynamic query optimization algorithm shows more applicability.