Federated SPARQL queries processing with replicated fragments

Gabriela Montoya*, Hala Skaf-Molli, Pascal Molli, Maria Esther Vidal

*Corresponding author for this work

Research output: Contribution to book/anthology/report/conference proceedingArticle in proceedingResearchpeer-review

14 Citations (Scopus)


Federated query engines provide a unified query interface to federations of SPARQL endpoints. Replicating data fragments from different Linked Data sources facilitates data re-organization to better fit federated query processing needs of data consumers. However, existing federated query engines are not designed to support replication and replicated data can negatively impact their performance. In this paper, we formulate the source selection problem with fragment replication (SSP-FR). For a given set of endpoints with replicated fragments and a SPARQL query, the problem is to select the endpoints that minimize the number of tuples to be transferred. We devise the Fedra source selection algorithm that approximates SSP-FR. We implement Fedra in the state-of-the-art federated query engines FedX and ANAPSID, and empirically evaluate their performance. Experimental results suggest that Fedra efficiently solves SSP-FR, reducing the number of selected SPARQL endpoints as well as the size of query intermediate results.

Original languageEnglish
Title of host publicationThe Semantic Web – ISWC 2015 - 14th International Semantic Web Conference, Proceedings
EditorsMathieu d’Aquin, Krishnaprasad Thirunarayan, Kavitha Srinivas, Paul Groth, Marcelo Arenas, Oscar Corcho, Markus Strohmaier, Jeff Heflin, Elena Simperl, Steffen Staab, Michel Dumontier
Number of pages16
Publication date1 Jan 2015
ISBN (Print)9783319250069
Publication statusPublished - 1 Jan 2015
Event14th International Semantic Web Conference, ISWC 2015 - Bethlehem, United States
Duration: 11 Oct 201515 Oct 2015


Conference14th International Semantic Web Conference, ISWC 2015
Country/TerritoryUnited States
SponsorCarlos Pedrinaci
SeriesLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)


  • Federated query processing
  • Fragment replication
  • Linked data
  • Source selection


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