层次聚集数据仓库中基于代价的聚集星查询优化技术
摘要
最近方法学提出的在数据仓库中改进星查询处理的方法是使用多维层次结构建立事实表上的聚集和索引 [ DRSN98, MRB99, KS01 ] 。 由于这个改善的组织模式,处理聚集星查询更改显著创建新建优化机会。一种重要优化技术就是所谓的预分组变换。 虽然在许多情况下这种变换技术能够希望用来改进查询处理计划, 但是仍可能出现一些反面情况。
在本文里，我们尝试运用一种基于代价的方法为预分组变换的优选申请。对我们的域的特殊特性采取入对价，我们确定最适当的算法为对预分组和派生详细的代价配方的关系运算。当适当的统计信息是可利用的方法时能决定(1)是否使用预分组变换和(2)各种各样的加法运算。 [资料来源：http://www.doc163.com]
原文
Abstract
A methodology recently proposed to improve processing of star queries on data warehouses is the clustering and indexing of
fact tables using their multidimensional hierarchies [DRSN98, MRB99, KS01]. Due to this improved organization schema,
processing of aggregation star queries changes dramatically creating new optimization opportunities. An important
optimization technique is the so-called pre-grouping transformation. Although this transformation is expected to improve the
query-processing plan in most cases, there are several cases where it is not beneficial.
In this paper we attempt to apply a cost-based method for the optimal application of the pre-grouping transformation. Taking [资料来源：http://Doc163.com]
into consideration the special characteristics of our domain we identify the most suitable algorithms for the operations related
to pre-grouping and derive detailed cost formulas for them. When proper statistical information is available the method can
decide (1) whether or not to use the pre-grouping transformation and (2) which combination of algorithms to use for the
various operations involved. [版权所有：http://DOC163.com]