Reifying RDF: What Works Well With Wikidata


Daniel Hernández, Aidan Hogan, Markus Krötzsch

Reifying RDF: What Works Well With Wikidata?

Abstract. In this paper, we compare various options for reifying RDF triples. We are motivated by the goal of representing Wikidata as RDF, which would allow legacy Semantic Web languages, techniques and tools – for example, SPARQL engines – to be used for Wikidata. However, Wikidata annotates statements with qualifiers and references, which require some notion of reification to model in RDF. We thus investigate four such options: (1) standard reification, (2) n-ary relations, (3) singleton properties, and (4) named graphs. Taking a recent dump of Wikidata, we generate the four RDF datasets pertaining to each model and discuss high-level aspects relating to data sizes, etc. To empirically compare the effect of the different models on query times, we collect a set of benchmark queries with four model-specific versions of each query. We present the results of running these queries against five popular SPARQL implementations: 4store, BlazeGraph, GraphDB, Jena TDB and Virtuoso.

Published at SSWS 2015 (Workshop paper)

Download PDF (last update: July 1 2016)

Citation details

  • Daniel Hernández, Aidan Hogan, Markus Krötzsch. Reifying RDF: What Works Well With Wikidata?. In Proceedings of the 11th International Workshop on Scalable Semantic Web Knowledge Base Systems (SSWS 2015), pp. 32–47. CEUR Workshop ProceedingsProperty "Publisher" has a restricted application area and cannot be used as annotation property by a user. 2015.


The published version contains an error in Table 5 and Figure 3: columns for standard reification and n-ary relations were switched there. Moreover, the minimum y-value (100 ms) used for Figure 3 was higher than the runtime of two query executions for Virtuoso (Q7: NR & SP), which thus did not show despite having been run successfully. These errors have been corrected in the PDF published here.


Semantic Web, Query languages, Wikidata