Relational nested optional join for efficient semantic web query processing

  • Authors:

  • Artem Chebotko;Mustafa Atay;Shiyong Lu;Farshad Fotouhi

  • Affiliations:

  • Department of Computer Science, Wayne State University, Detroit, Michigan;Department of Computer Science, Wayne State University, Detroit, Michigan;Department of Computer Science, Wayne State University, Detroit, Michigan;Department of Computer Science, Wayne State University, Detroit, Michigan

  • Venue:
  • APWeb/WAIM'07 Proceedings of the joint 9th Asia-Pacific web and 8th international conference on web-age information management conference on Advances in data and web management
  • Year:
  • 2007

Quantified Score

Hi-index 0.00

Visualization

Abstract

Increasing amount of RDF data on the Web drives the need for its efficient and effective management. In this light, numerous researchers have proposed to use RDBMSs to store and query RDF annotations using the SQL and SPARQL query languages. The first few attempts at SPARQL-to-SQL translation revealed non-trivial challenges related to correctness and efficiency of such translation in the presence of nested optional graph patterns. In this paper, we propose to extend relational databases with a novel relational operator, nested optional join (NOJ), that is more efficient than left outer join in processing nested optional graph patterns. We design three efficient algorithms to implement the new operator in relational databases: (1) nested-loops NOJ algorithm, NL-NOJ, (2) sort-merge NOJ algorithm, SM-NOJ, and (3) simple hash NOJ algorithm, SH-NOJ. Based on a real life RDF dataset, we demonstrate the efficiency of our algorithms by comparing them with the corresponding left outer join implementations.