Exploiting Path Indexes to Answer Complex Queries in Ontology Repository

The ontology repository has widely been used for storing and querying over ontology data. Recently the ontology repository gets more attentions as a component of ubiquitous systems. This paper describes use of the path index to answer complex queries in ontology repository. Studies show that two types of queries namely chain queries and star queries frequently occur in SPARQL queries. Instead of using join operations over several triple indexes, we proposed to use path indexes for such queries, which in turn improve the query performance reducing the number of multiple join operations. Our experiments show that the proposed method enhances the query performance than using only indexes based on single triple pattern.