DM4中的多查询优化器  

Multi-query optimizer in DM4

作　　者：许向阳[1] 郭亚[1] 

机构地区：[1]华中科技大学计算机科学与技术学院,湖北武汉430074

出　　处：《华中科技大学学报（自然科学版）》2005年第3期49-52,共4页Journal of Huazhong University of Science and Technology(Natural Science Edition)

基　　金：国家高技术研究发展计划资助项目 (2 0 0 2AA4Z3110 ) .

摘　　要：在国产数据库管理系统DM4已有的查询优化器基础上 ,设计了一组公共操作识别和重组规则 ,分析了公共操作的代价 ,采用启发式公共操作搜索和计划树重组算法 ,实现了两阶段体系结构的多查询优化器 ,有效地利用了多查询间的公共操作 ,同时对算法复杂度分析证明了公共操作搜索策略对优化器性能的低影响性 .Based on existing query optimizer in a native database management system DM4, a set of rules for identifying common operators and rewriting plans were designed, and the cost of common operators analyzed. The heuristic common operators′ search and plan trees rewriting algorithm were exploited to fulfill the multi query optimizer of two phase system architecture. It utilized common operators among queries. Algorithmic complexity analysis proves that the searching strategy for common operators has little effect on the performance of the optimizer.

关 键 词：多查询优化器 公共操作 两阶段体系结构 

分 类 号：TP311[自动化与计算机技术—计算机软件与理论]