对象代理数据库的虚属性查询优化方法

Query Optimization for Virtual Attributes in Object Deputy Database

为对象代理数据库的虚属性查询提出两种优化方法——表达式提升和虚属性合并。表达式提升将虚属性查询转换为对源类中实属性的查询;虚属性合并是对查询涉及的属于相同源对象的多个虚属性,一次性获取相应源对象的属性值用于虚属性值的计算,避免多次访问同一源对象。通过实验分析了这两种方案对虚属性查询的性能影响,实验结果表明,对于虚属性和代理层数较多的查询,表达式提升和虚属性合并的方法极大提升了查询效率。

Two methods ,expression promotion and virtual attributes merger are proposed .Expression promotion will rewrite the query on virtual attributes to their inherited attributes .Virtual attributes merger will access all attributes value belonging to the same source object for virtual attribute computation .The experimental results demonstrate that the query with our methods can achieve a great improvement .