精确控制执行计划的多表Hint研究与实现  

Research and implementation of table-join Hint for precision control on execution plan

作　　者：饶路[1] 顾云苏 何清法[2] 

机构地区：[1]北京信息控制研究所,北京100048 [2]北京神舟航天软件技术有限公司,北京100094

出　　处：《计算机工程与设计》2010年第18期3993-3997,4027,共6页Computer Engineering and Design

基　　金：国家863高技术研究发展计划基金项目(2005AA4Z3020)

摘　　要：针对多表查询中庞大执行计划空间导致的多表Hint控制不精确问题,提出了一种基于关系代数连接运算的多表Hint控制模型。建立了多表Hint与优化器表连接执行计划之间的一一映射关系,在不改变优化器现有理论架构的基础上实现了多表Hint对执行计划各个部分的精确控制。提出了一种冲突判断规则,不仅能够快速准确地判断出各种多表Hint在最大表参数集合不相同情况下的语义冲突,而且确保了控制模型具备良好的扩展性。通过在神舟OSCAR数据库上的应用,表明该模型的有效性和高效性。To resolve the problem of precision control on execution plan with table-join Hint, which is caused by the enormous execution plan space when several tables are joined for a query request, a table-join Hint control model based on the join operator of relational algebra is proposed. In this model, a bijection between table-join Hint and optimizer execution plan is defined to provide maintenance of accuracy for every part of the plan, without any modification of the existing theory of optimizer construction. Furthermore, a conflict- estimation rule is presented, which can not only be used to figure out the result of semantic conflict among all sorts of table-join Hints quickly and exactly when the Hints have the different set of table parameters, but also provide the excellent extensibility for the control model. Finally, both effectivity and efficiency of this model are testified in Shenzhou OSCAR database.

关 键 词：执行计划空间 多表Hint 优化器 冲突判断规则 数据库 

分 类 号：TP311.131[自动化与计算机技术—计算机软件与理论]