QLever (pronounced /ˈklɛvər/ KLEH-ver, as in "clever") is an open-source triplestore and graph database developed by a team at the University of Freiburg led by Hannah Bast. QLever performs high-performance queries of semantic Web knowledge bases, including full-text search within text corpuses.[1] A specialized user interface for QLever predictively autocompletes SPARQL queries.[2]
| Original author(s) | Hannah Bast, Björn Buchhold, et al.[1] |
|---|---|
| Initial release | 2017 |
| Repository | github |
| Written in | C++ |
| Standard(s) | SPARQL |
| Available in | English |
| Type | Graph database |
| License | Apache License |
| Website | qlever |
QLever is one of the candidates to replace Blazegraph as the triplestore for the Wikidata Query Service. A 2023 study found that, compared to other triplestores, QLever achieved fast execution of successful queries but offered limited support for complex SPARQL constructs.[3]
Contents
editThe official QLever server provides access to the following datasets:[4]
- Wikidata
- Wikimedia Commons
- Freebase
- OpenStreetMap
- OpenHistoricalMap
- UniProt
- PubChem
- DBLP
- OpenCitations
- IMDb
- Integrated Authority File
- YAGO
- DBpedia
- Wallscope Olympics database
Although the QLever engine lacks support for GeoSPARQL functions per se, the official server precomputes a subset of GeoSPARQL relationships into dedicated triples for OpenStreetMap and OpenHistoricalMap data.[5]
See also
editReferences
edit- ^ a b Bast & Buchhold 2017.
- ^ Bast et al. 2021.
- ^ Lam, An Ngoc; Elvesæter, Brian; Martin-Recuerda, Francisco (2023). Evaluation of a Representative Selection of SPARQL Query Engines Using Wikidata. Extended Semantic Web Conference. Lecture Notes in Computer Science. Vol. 13870. Springer, Cham – via SpringerLink.
- ^ "QLever". Freiburg im Breisgau: University of Freiburg Chair for Algorithms and Data Structures. Retrieved 13 July 2024.
- ^ Bast et al. 2021.
Further reading
edit- Bast, Hannah; Brosi, Patrick; Kalmbach, Johannes; Lehmann, Axel (November 2–5, 2021). An Efficient RDF Converter and SPARQL Endpoint for the Complete OpenStreetMap Data (PDF). SIGSPATIAL. Beijing: Association for Computing Machinery. doi:10.1145/3474717.3484256. ISBN 978-1-4503-8664-7.
- Bast, Hannah; Buchhold, Björn (November 6–10, 2017). QLever: A Query Engine for Efficient SPARQL+Text Search (PDF). Conference on Information and Knowledge Management. Singapore: Association for Computing Machinery. doi:10.1145/3132847.3132921. ISBN 978-1-4503-4918-5.
- Bast, Hannah; Kalmbach, Johannes; Klumpp, Theresa; Kramer, Florian; Schnelle, Niklas (29 April 2021). "Efficient SPARQL Autocompletion via SPARQL". arXiv:2104.14595v1 [cs.DB].