【作者】 冯玉才； 黄琳倩；

【Author】 Feng Yucai,Huang Linqian (School of Computer Science,HUST Wuhan,430074,China)

【机构】 华中理工大学计算机科学与工程学院；

【摘要】 在关系数据库管理系统DM3中,我们实现了外联接及其优化.本文介绍了DM3中的外联接查询的优化策略和实现方法.更多还原

【Abstract】 In this paper,we present the implement method of outer join optimization of DM3 database management system(DBMS).Utilizing the principle mentioned by Galindo-Learia et.and the present strategy of query optimization of DM3,we rewrite the formation of the join expression firstly and then construct the operator tree bottom-up.We also discuss how to construct the operator tree giving attention to both the space of searching and the cost of join.更多还原