CostFed is an index-assisted federation engine for federated SPARQL query processing over multiple SPARQL endpoints. CostFed makes use of statistical information collected from endpoints to perform efficient source selection and cost-based query planning. In contrast to the state of the art, it relies on a non-linear model for the estimation of the selectivity of joins. Therewith, it is able to generate better plans than the state-of-the-art federation engines. In an experimental evaluation based on FedBench benchmark, we show that CostFed is 3 to 121 times faster than the state of the art SPARQL endpoint federation engines.
The CostFed live demo comprise the following two main applications:
The query formulator/executer is availble here. This is the main interface which allows executing both federated and non-federated queries.
The start CostFed-web and create your own local demo, the Dockerfile can be downloaded from here
To help user, we provided some federated queries here from FedBench and LargeRDFBench which can be directly executed.
The queries used in the evaluation can be downloaded from FedBench and LargeRDFBech homepage.
All the datasets and corresponding virtuoso SPARQL endpoints can be downloaded from the links given below. You may start a SPARQL endpoint from bin/start.bat (for windows) and bin/start_virtuoso.sh (for linux).
We have compared 5 - FedX, SPLENDID, ANAPSID, SemaGrow, HiBISUCuS - state-of-the-art SPARQL endpoint federation systems with CostFed. Our complete evaluation results can be downloaded from here.
We are especially thankful to Andreas Schwarte (fluid Operations, Germany), Olaf Görlitz (University Koblenz, Germany), and Angelos Charalambidis (Institute of Informatics and Telecommunication, Paraskevi, Greece) for all their email conversations, feedbacks, and explanations.
