---
_id: '25212'
abstract:
- lang: eng
  text: "Finding a good query plan is key to the optimization of query runtime. This
    holds in particular for cost-based federation\r\nengines, which make use of cardinality
    estimations to achieve this goal. A number of studies compare SPARQL federation
    engines across different performance metrics, including query runtime, result
    set completeness and correctness, number of sources selected and number of requests
    sent. Albeit informative, these metrics are generic and unable to quantify and
    evaluate the accuracy of the cardinality estimators of cost-based federation engines.
    To thoroughly evaluate cost-based federation engines, the effect of estimated
    cardinality errors on the overall query runtime performance must be measured.
    In this paper, we address this challenge by presenting novel evaluation metrics
    targeted at a fine-grained benchmarking of cost-based federated SPARQL query engines.
    We evaluate five cost-based federated SPARQL query engines using existing as well
    as novel evaluation metrics by using LargeRDFBench queries. Our results provide
    a detailed analysis of the experimental outcomes that reveal novel insights, useful
    for the development of future cost-based federated SPARQL query processing engines."
article_type: original
author:
- first_name: Umair
  full_name: Qudus, Umair
  id: '83392'
  last_name: Qudus
  orcid: 0000-0001-6714-8729
- first_name: Muhammad
  full_name: Saleem, Muhammad
  last_name: Saleem
- first_name: Axel-Cyrille
  full_name: Ngonga Ngomo, Axel-Cyrille
  id: '65716'
  last_name: Ngonga Ngomo
- first_name: Young-Koo
  full_name: Lee, Young-Koo
  last_name: Lee
citation:
  ama: Qudus U, Saleem M, Ngonga Ngomo A-C, Lee Y-K. An Empirical Evaluation of Cost-based
    Federated SPARQL Query Processing Engines. <i>Semantic Web</i>. 12(6):843-868.
    doi:<a href="https://doi.org/10.3233/SW-200420">10.3233/SW-200420</a>
  apa: Qudus, U., Saleem, M., Ngonga Ngomo, A.-C., &#38; Lee, Y.-K. (n.d.). An Empirical
    Evaluation of Cost-based Federated SPARQL Query Processing Engines. <i>Semantic
    Web</i>, <i>12</i>(6), 843–868. <a href="https://doi.org/10.3233/SW-200420">https://doi.org/10.3233/SW-200420</a>
  bibtex: '@article{Qudus_Saleem_Ngonga Ngomo_Lee, title={An Empirical Evaluation
    of Cost-based Federated SPARQL Query Processing Engines}, volume={12}, DOI={<a
    href="https://doi.org/10.3233/SW-200420">10.3233/SW-200420</a>}, number={6}, journal={Semantic
    Web}, publisher={ISO Press}, author={Qudus, Umair and Saleem, Muhammad and Ngonga
    Ngomo, Axel-Cyrille and Lee, Young-Koo}, pages={843–868} }'
  chicago: 'Qudus, Umair, Muhammad Saleem, Axel-Cyrille Ngonga Ngomo, and Young-Koo
    Lee. “An Empirical Evaluation of Cost-Based Federated SPARQL Query Processing
    Engines.” <i>Semantic Web</i> 12, no. 6 (n.d.): 843–68. <a href="https://doi.org/10.3233/SW-200420">https://doi.org/10.3233/SW-200420</a>.'
  ieee: 'U. Qudus, M. Saleem, A.-C. Ngonga Ngomo, and Y.-K. Lee, “An Empirical Evaluation
    of Cost-based Federated SPARQL Query Processing Engines,” <i>Semantic Web</i>,
    vol. 12, no. 6, pp. 843–868, doi: <a href="https://doi.org/10.3233/SW-200420">10.3233/SW-200420</a>.'
  mla: Qudus, Umair, et al. “An Empirical Evaluation of Cost-Based Federated SPARQL
    Query Processing Engines.” <i>Semantic Web</i>, vol. 12, no. 6, ISO Press, pp.
    843–68, doi:<a href="https://doi.org/10.3233/SW-200420">10.3233/SW-200420</a>.
  short: U. Qudus, M. Saleem, A.-C. Ngonga Ngomo, Y.-K. Lee, Semantic Web 12 (n.d.)
    843–868.
date_created: 2021-10-01T06:52:52Z
date_updated: 2025-09-11T09:50:14Z
ddc:
- '000'
department:
- _id: '574'
doi: 10.3233/SW-200420
file:
- access_level: closed
  content_type: application/pdf
  creator: uqudus
  date_created: 2024-01-13T11:35:53Z
  date_updated: 2024-01-13T11:35:53Z
  file_id: '50483'
  file_name: swj2604.pdf
  file_size: 978478
  relation: main_file
  success: 1
file_date_updated: 2024-01-13T11:35:53Z
has_accepted_license: '1'
intvolume: '        12'
issue: '6'
keyword:
- SPARQL
- benchmarking
- cost-based
- cost-free
- federated
- querying
language:
- iso: eng
page: 843-868
project:
- _id: '410'
  name: 'KnowGraphs: KnowGraphs: Knowledge Graphs at Scale'
publication: Semantic Web
publication_identifier:
  issn:
  - 2210-4968
publication_status: accepted
publisher: ISO Press
status: public
title: An Empirical Evaluation of Cost-based Federated SPARQL Query Processing Engines
type: journal_article
user_id: '83392'
volume: 12
year: '2021'
...