一种基于维层次编码的OLAP聚集查询算法  

A Novel Aggregation Algorithm for Online Analytical Processing Queries Evaluation Based on Dimension Hierarchical Encoding

作　　者：胡孔法[1] 董逸生[1] 徐立臻[1] 杨科华[1] 

机构地区：[1]东南大学计算机科学与工程系,南京210096

出　　处：《计算机研究与发展》2004年第4期608-614,共7页Journal of Computer Research and Development

基　　金：国家自然科学基金项目 (5 98895 0 4);国家"八六三"高技术研究发展计划基金项目(2 0 0 2AA2 3 10 71);江苏省"九五"重点攻关基金项目(BG980 17 1);江苏省"十五"高科技基金项目(BG2 0 0 10 13 )

摘　　要：联机分析处理 (OLAP)查询往往需在海量数据上进行即席的复杂分组聚集查询 ,在其SQL语句中通常包含多表连接和分组聚集操作 ,因而减少多表连接和压缩关键字 ,以及对查询数据进行有效地分组聚集操作 ,成为ROLAP查询处理的关键问题 提出了一种基于维层次编码的新型预分组聚集算法DHEPGA DHEPGA算法充分利用了编码长度较小的维层次编码及其前缀 ,来快速检索出与查询关键字相匹配的维层次编码 ,求得维层次属性的查询范围 ,减少了I/O开销 ,提高了OLAP查询效率 理论分析和实验结果表明 。The OLAP (online analytical processing) queries are ad hoc complex aggregation queries on the massive data set These queries include multi table join and aggregation operation in their SQL clauses As a result, how to reduce multi table join, compress the key word and effectively aggregate the query data becomes the key issue for ROLAP(relational OLAP)query evaluation To solve this problem, a novel pre grouping aggregation algorithm DHEPGA(pre grouping aggregation based on the dimension hierarchical encoding) is proposed in this paper By using the small dimension hierarchical encoding and its hierarchical prefix path, DHEPGA can rapidly retrieve the matching dimension hierarchical encoding and evaluate the set of query ranges for each dimension As a result, this algorithm can greatly reduce the disk I/Os and highly improve the efficiency of OLAP queries The analytical and experimental results show that the DHEPGA algorithm proposed is more efficient than other existing ones

关 键 词：OLAP(联机分析处理) 聚集查询 维层次编码 层次前缀 

分 类 号：TP311[自动化与计算机技术—计算机软件与理论]