基于双时态RDF模型的索引方法  

Indexing Bi-temporal RDF Model

作　　者：王引娣 章哲庆 严丽 WANG Yin-di;ZHANG Zhe-qing;YAN Li(College of Computer Science and Technology,Nanjing University of Aeronautics and Astronautics,Nanjing 210000,China)

机构地区：[1]南京航空航天大学计算机科学与技术学院,南京210000

出　　处：《计算机科学》2021年第4期63-69,共7页Computer Science

基　　金：江苏省自然科学基金(BK20191274);国家自然科学基金(61772269)。

摘　　要：RDF(Resource Description Framework)已被广泛用于大数据的语义表示与处理。传统的RDF只能表示静态语义,无法满足时间敏感场景下随时间动态处理语义的需求。为此,几种时态RDF模型已被提出,包括支持事务时间或有效时间的时态RDF模型,以及同时支持事务时间和有效时间的双时态RDF模型。为有效支持大规模时态RDF的高效处理,文中提出了一种基于双时态模型的时态RDF三层索引结构。第一层根据最大更新次数将双时态RDF数据划分为不同的数据子集;第二层在每一个数据子集上分别建立一棵四叉树来索引时间信息;第三层构建了包含3种组合键的复合位图来索引RDF三元组的主体、谓词和客体信息。实验从索引构建时间、索引占用空间,以及查询所需时间3个方面对所提时态RDF索引结构进行验证,结果表明,所提索引方案能有效缩短查询时间并提高查询效率。RDF(Resource Description Framework)has been widely used for semantic representation and processing of big data.Traditional RDF can only represent static semantics and can not meet the needs of processing semantics dynamically over time in time-sensitive scenarios.Therefore,many temporal RDF models are proposed,including RDF model for transaction time,RDF model for valid time,and bi-temporal RDF model that supports both transaction time and valid time.To support efficient proces-sing of large-scale temporal RDF data,this paper proposes a three-level index structure based on bi-temporal RDF model.Specifi-cally,in the first level of this index structure,the dataset is divided into different subsets according to the update times of the temporal RDF data.In the second level,a quadtree is built for indexing time information in each subset,and in the third level,the bitmap with three composite keys is used to index the subject,predicate,object of RDF triples.Experiments are conducted from three aspects:the time of building index,the index size,and the required query time.Experimental results show that the proposed indexing scheme can reduce the query time effectively and improve the query performance.

关 键 词：RDF 时态信息 三层索引 四叉树 位图索引 

分 类 号：TP399[自动化与计算机技术—计算机应用技术]