Hi Alina,
On 07/17/2012 06:48 PM, Alina Balusescu wrote:
> Hi all,
>
> I need to query DBpedia to get the genre and release date of all the
> songs that got picked in the BBC Radio 4 Desert Island Discs show. I'm
> using the Jena API, in Java, to send all the SPARQL queries to the
> http://dbpedia.org/sparql endpoint. Because I only have the title of
> the songs and the name of the artist, I need to query by these
> strings. To restrict the search, I've added the constraints on the
> resource type. If I don't put a type constraint, the query times out.
> Here is one of the queries I use for getting the song URI, genre and
> release date:
>
> SELECT DISTINCT *
> WHERE {
> {
> ?song rdf:type <http://dbpedia.org/ontology/Single> .
> ?song rdfs:label ?songTitle .
> OPTIONAL {?song dbpedia-owl:genre ?genre} .
> OPTIONAL {?song dbpedia2:genre ?genre} .
> OPTIONAL {?song dbpedia-owl:releaseDate ?releaseDate} .
> FILTER ( regex(?songTitle, "Fallen Soldier", "i") ) .
> FILTER (LANG(?songTitle) = 'en') .
> }
> UNION {
> ?song rdf:type <http://dbpedia.org/ontology/MusicalWork> .
> ?song rdfs:label ?songTitle .
> OPTIONAL {?song dbpedia-owl:genre ?genre} .
> OPTIONAL {?song dbpedia2:genre ?genre} .
> OPTIONAL {?song dbpedia-owl:releaseDate ?releaseDate} .
> FILTER ( regex(?songTitle, "Fallen Soldier", "i") ) .
> FILTER (LANG(?songTitle) = 'en') .
> }
> UNION {
> ?song rdf:type <http://dbpedia.org/ontology/Work> .
> ?song rdfs:label ?songTitle .
> OPTIONAL {?song dbpedia-owl:genre ?genre} .
> OPTIONAL {?song dbpedia2:genre ?genre} .
> OPTIONAL {?song dbpedia-owl:releaseDate ?releaseDate} .
> FILTER ( regex(?songTitle, "Fallen Soldier", "i") ) .
> FILTER (LANG(?songTitle) = 'en') .
> }
> UNION {
> ?song rdf:type <http://umbel.org/umbel/rc/MusicalComposition> .
> ?song rdfs:label ?songTitle .
> OPTIONAL {?song dbpedia-owl:genre ?genre} .
> OPTIONAL {?song dbpedia2:genre ?genre} .
> OPTIONAL {?song dbpedia-owl:releaseDate ?releaseDate} .
> FILTER ( regex(?songTitle, "Fallen Soldier", "i") ) .
> FILTER (LANG(?songTitle) = 'en') .
> }
> } LIMIT 1
Actually, regex is an extremely expensive operation, try to use
bif:contains instead.
So your query should like the following:
SELECT DISTINCT *
WHERE {
{
?song rdf:type <http://dbpedia.org/ontology/Single> .
?song rdfs:label ?songTitle .
OPTIONAL {?song dbpedia-owl:genre ?genre} .
OPTIONAL {?song dbpprop:genre ?genre} .
OPTIONAL {?song dbpedia-owl:releaseDate ?releaseDate} .
FILTER ( bif:contains( ?songTitle, 'Fallen and Soldier')) .
FILTER (LANG(?songTitle) = 'en') .
}
UNION {
?song rdf:type <http://dbpedia.org/ontology/MusicalWork> .
?song rdfs:label ?songTitle .
OPTIONAL {?song dbpedia-owl:genre ?genre} .
OPTIONAL {?song dbpprop:genre ?genre} .
OPTIONAL {?song dbpedia-owl:releaseDate ?releaseDate} .
FILTER ( bif:contains( ?songTitle, 'Fallen and Soldier')).
FILTER (LANG(?songTitle) = 'en') .
}
UNION {
?song rdf:type <http://dbpedia.org/ontology/Work> .
?song rdfs:label ?songTitle .
OPTIONAL {?song dbpedia-owl:genre ?genre} .
OPTIONAL {?song dbpprop:genre ?genre} .
OPTIONAL {?song dbpedia-owl:releaseDate ?releaseDate} .
FILTER ( bif:contains( ?songTitle, 'Fallen and Soldier')) .
FILTER (LANG(?songTitle) = 'en') .
}
UNION {
?song rdf:type <http://umbel.org/umbel/rc/MusicalComposition> .
?song rdfs:label ?songTitle .
OPTIONAL {?song dbpedia-owl:genre ?genre} .
OPTIONAL {?song dbpprop:genre ?genre} .
OPTIONAL {?song dbpedia-owl:releaseDate ?releaseDate} .
FILTER ( bif:contains( ?songTitle, 'Fallen and Soldier')) .
FILTER (LANG(?songTitle) = 'en') .
}
} LIMIT 1
>
> I've also tried to split the query into two: first to get the song URI
> by title, and then get the genre and release date (which is a bit
> faster than this one, but still very slow; sometimes it times out as
> it is.. ).
> My question is, is there any way to optimize this search by literals ?
> It takes up to 5 minutes per song to return results and I need to
> handle about 14,000 of them.
>
> Thanks in advance!
>
> Regards,
> Alina Elena Băluşescu
>
> MSc student in Advanced Computer Science department
> The University of Manchester
Hope it works for you now.
--
Kind Regards
Mohamed Morsey
Department of Computer Science
University of Leipzig
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