OntoQuad: Native High-Speed RDF DBMS for Semantic Web Alexander Potocki 1 , Anton Polukhin 1 , Grigory Drobyazko 2 , Daniel Hladky 2 , Victor Klintsov 2 , and J¨ org Unbehauen 3 1 Eventos, Moscow, Russia {alexander.potocki,anton.polukhin}@my-eventos.com 2 National Research University - Higher School of Economics (NRU HSE), Moscow, Russia {gdrobyazko,vklintsov,daniel.hladky}@hse.ru 3 Universit¨ at Leipzig, Institut f¨ ur Informatik, Leipzig, Germany unbehauen@informatik.uni-leipzig.de Abstract. In the last years native RDF stores made enormous progress in closing the performance gap compared to RDBMS. This albeit smaller gap, however, still prevents adoption of RDF stores in scenarios with high requirements on responsiveness. We try to bridge the gap and present a native RDF store “OntoQuad” and its fundamental design principles. Basing on previous researches, we develop a vector database schema for quadruples, its realization on index data structures, and ways to effi- ciently implement the joining of two and more data sets simultaneously. We also offer approaches to optimizing the SPARQL query execution plan which is based on its heuristic transformations. The query perfor- mance efficiency is checked and proved on BSBM tests. The study results can be taken into consideration during the development of RDF DBMS’s suitable for storing large volumes of Semantic Web data, as well as for the creation of large-scale repositories of semantic data. Keywords: RDF, SPARQL, index, multiple joins, query optimization 1 Introduction The research goals addressed in this article are: creation of a native RDF DBMS that is efficient in terms of its performance, does not require the use of a relational DB and translation of SPARQL into SQL, and supports such recommendations of the World Wide Web Consortium (W3C) as RDF, SPARQL 1.1 [1], SPARQL protocol 1 ; elaboration on existing approaches to the creation of a native RDF DBMS information architecture; development of new heuristic algorithms for optimizing query execution plans. An RDF data representation model is one of the foundations of the Semantic Web concept developed and being promoted by the W3C. Accordingly, an RDF DBMS is one of its fundamental underlying tools. The efficiency of any given RDF DBMS depends on its capabilities tailored 1 http://www.w3.org/standards/semanticweb/