Abdoul Macina - Optimising SPARQL query processing in distributed knowledge graphs
Channel: ISAE-ENSMA officiel
Date: 30/01/2017

An increasing number of linked knowledge bases are openly accessible over the Internet. Distributed Query Processing (DQP) techniques are developed to query multiple knowledge bases coherently. However, a precise semantics has to be defined to specify the precise expected results, and query performance issues arise. In this paper, we define SPARQL DQP over distributed RDF graphs. We propose a SPARQL and RDF-compliant DQP semantics. We improve performance through query planning heuristics that generate Basic Graph Pattern-based sub-queries designed to maximise the parts of the query processed by the remote endpoints. We evaluate our DQP engine considering a query set representative of most common SPARQL clauses and different data distribution schemes. Results show a significant reduction of the number of remote queries executed and the query execution time while preserving completeness.