SPARQL query returns incomplete results

[José Alejandro Pérez Pirela]

I'm graduate student from Simón Bolívar University. Currently I'm taking a course of semantic web in which we are making use of some endpoints. One of these is LinkedGeoData. In particular, I'm working with this endpoint. I was trying to run the following query on Virtuoso:

Select ?thing ?long ?lat
where{
   ?thing rdfs:label ?label;
   geo:lat ?lat;
   geo:long ?long.

   filter (
       (?long > -73.48374) && (?long < -59.38864) && (?lat > 0.76885) && (?lat < 14.82637)
   ) .

}

This query means: give me all the things locate inside this square. The problem is that the results appear to be truncate, that is, only retrieve me 1000 results. With other queries I notice that there are several results that are not included in the dataset that the last query returns. What is the problem?

[Claus Stadler]

Hi Jose,

Result set limits are capped at 1000 result rows.

If you are using Java, you could e.g. use our "jena-sparql-api" project (https://github.com/AKSW/jena-sparql-api), which provides classes that enable you to work around the result set size limit pretty easily (this library also supports caching each of the individual retrieved result sets, such that if you have to restart your process, it will run on cache up to the point where it was cancelled).

>> With other queries I notice that there are several results that are not included in the dataset that the last query returns. What is the problem?

Can you please give a concrete example of where you think something goes wrong? The easiest would be to post the full HTTP urls you use to retrieve the SPARQL result sets.

Cheers,
Claus

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Dipl. Inf. Claus Stadler
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[José Alejandro Pérez Pirela]

Hi Claus,

>> Result set limits are capped at 1000 result rows.

Now It all makes sense!

I was trying to enrich the data I have in a graph database. My idea was to extract some information from LinkedGeoData and them upload it into the graph. If  the jena-sparql-api project allow me to set the result size limit then I will try it, however, does exists an easy way to retrieve unlimited data from LinkedGeoData instead of using jena?

Thanks!