An empirical analysis of semantic web mechanisms for storage and query of ontologies in relational databases

Different platforms and mechanisms have been developed to store and query ontologies in relational databases (RDB). However, very little have been done to identify and discuss the mechanisms used. In this paper, two of the most popular open-source ontology storage platforms namely Sesame and Jena are used to identify the mechanisms used to store ontologies in RDB. Two ontologies are loaded in the repositories and the data within the repositories are analyzed to identify the mechanism(s). The experiments shows that (1) Sesame uses two mechanisms namely vertical partitioning and normalized triple store mechanisms, (2) Jena uses one specific mechanism namely normalized triple store to store ontologies, (3) in Sesame, every ontology has its own database schema, and (4) in Jena, all ontologies have the same database schema.