CostFed: Cost-Based Query Optimization for SPARQL Endpoint Federation

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.

Live Demo

The CostFed live demo comprise the following two main applications:

Used Benchmarks

The queries used in the evaluation can be downloaded from FedBench and LargeRDFBech homepage.

Datasets Availability

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/ (for linux).

Dataset Data-dump Windows Endpoint Linux Endpoint Local Endpoint Url Live Endpoint Url
ChEBI Download Download Download your.system.ip.address:8890/sparql -
DBPedia-Subset Download Download Download your.system.ip.address:8891/sparql
DrugBank Download Download Download your.system.ip.address:8892/sparql
Geo Names Download Download Download your.system.ip.address:8893/sparql
Jamendo Download Download Download your.system.ip.address:8894/sparql
KEGG Download Download Download your.system.ip.address:8895/sparql
Linked MDB Download Download Download your.system.ip.address:8896/sparql
New York Times Download Download Download your.system.ip.address:8897/sparql -
Semantic Web Dog Food Download Download Download your.system.ip.address:8898/sparql
Affymetrix Download Download Download your.system.ip.address:8899/sparql

Evaluation Results and Runtime Errors

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.