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sparqldbpedia

DBPedia's SPARQL and SNORQL returning different results

In the DBpedia SPARQL endpoint, running

PREFIX dc: <http://purl.org/dc/elements/1.1/>
PREFIX : <http://dbpedia.org/resource/>
PREFIX dbpedia2: <http://dbpedia.org/property/>

SELECT ?a (3+3 AS ?y)
WHERE 
{ 
   ?a dc:description "English footballer" .
   ?a dbpedia2:placeOfBirth :Merseyside .
}

Shows all English Footballers who were born in Merseyside, with column y just displaying the value 6 on every row [result link]; however, the same query on the SNORQL endpoint displays an error:

Virtuoso 37000 Error SP030: SPARQL compiler, line 16: syntax error at '3'
before 'AS' SPARQL query: define sql:big-data-const 0 #output-
format:application/sparql-results+json define input:default-graph-uri PREFIX 
owl: PREFIX xsd: PREFIX rdfs: PREFIX rdf: PREFIX foaf: PREFIX dc: PREFIX : 
PREFIX dbpedia2: PREFIX dbpedia: PREFIX skos: PREFIX pos: PREFIX dbo: SELECT 
?a (3 3 AS ?y) WHERE { ?a dc:description "English footballer" . ?a 
dbpedia2:placeOfBirth :Merseyside . }

Even more strangely, using any of the other 3 arithmetic operators does work in the SNORQL endpoint (e.g. with division)

A previous question has implied that the SPARQL and SNORQL endpoints should return the same result, so what's going on here?!

Solution

  • The snorql code used the 'escape' javascript function which is not the correct function to encode a piece of text that needs to be embedded as an parameter argument to the official /sparql endpoint.

    This caused the + character to be transferred as literal, and decoded by the /sparql endpoint as a space character, altering the syntax of your query.

    We fixed the snorql code on dbpedia.org to use the encodeURIComponent as in:

    url = url + '&query=' + encodeURIComponent(query_text);