Abstract. Federated query engines allow to consume linked data from SPARQL endpoints. Replicating data fragments from different sources allows to re-organize data to better fit federated query processing of data consumers. However, existing federated query engines poorly support replication. In this paper, we propose a replication-aware federated query engine that extends state-of-art federated query engine ANAPSID and FedX with Fedra, a source selection strategy that approximates the source selection problem with fragments replication (SSP-FR). For a given set of endpoints with replicated fragments and a SPARQL query, the problem is to find the endpoints to contact in order to minimize the number of tuples to transfer from endpoints to the federated query engines. 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.
Fedra REF is a replication-aware source selection that uses data locality produced by replicated fragments to enhance federated query engines performances.
Federated SPARQL Queries Processing with Replicated Fragments
International Semantic Web Conference
Computer Science