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ad-freiburg / qlever

Very fast SPARQL Engine, which can handle very large knowledge graphs like the complete Wikidata, offers context-sensitive autocompletion for SPARQL queries, and allows combination with text search. It's faster than engines like Blazegraph or Virtuoso, especially for queries involving large result sets.
Apache License 2.0
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QLever API documentation #1483

Closed pfps closed 3 weeks ago

pfps commented 3 weeks ago

Is there a complete description of the API documentation? I'm in particular looking for a way to get execution statistics on queries such as time taken and space used.

It would be great if there was a way of getting a compact result (e.g., CSV) plus the execution statistics. It would be even better if there was a way of just getting the number of results plus execution statistics (without having to use COUNT).

hannahbast commented 3 weeks ago

@pfps The API for standard media types like application/csv, application/tab-separated-values, and application/sparql-results+json is dictated by the SPARQL standard, see https://www.w3.org/TR/sparql11-results-csv-tsv . In particular, we can't just add timing information to the TSV or CSV because that would violate the standard.

Instead, QLever additionally supports an own media type application/qlever-results+json, which, in particular, is used by the QLever UI. When you ask for that media type, you get the result as a JSON (in a more compact form then with application/sparql-results+json) and also information about the running time of the query, the query execution plan, etc. The JSON is self-explanatory, just issue the corresponding curl command for a simple query, for example:

curl -s https://qlever.cs.uni-freiburg.de/api/wikidata -H "Accept: application/qlever-results+json" -H "Content-type: application/sparql-query" --data "SELECT * WHERE { ?s ?p ?o } LIMIT 1" | jq
pfps commented 3 weeks ago

Thanks

hannahbast commented 3 weeks ago

@pfps I have now also created a page on the QLever Wiki providing that information: https://github.com/ad-freiburg/qlever/wiki/QLever-API-documentation

pfps commented 3 weeks ago

Excellent.

pfps commented 3 weeks ago

I'm using that interface and it works well, except that it seems to limit the number of results to 1000000. I don't mind having only (!) 1000000 results in the response but the resultsize value is also 1000000 when it would be useful to have it be the real value.

pfps commented 3 weeks ago

Also, is there a way to clear the cache like you can do in the GUI?