Hi Nicola,
A slightly faster form is to make one OPTIONAL with an UNION instead of
two OPTIONALs.
e.g.
CONSTRUCT {<http://dbpedia.org/resource/Coen_brothers> ?p ?o.
?sub ?p_sub ?o_sub.
?type ?p_type ?o_type.
}
where {
<http://dbpedia.org/resource/Coen_brothers> ?p ?o
OPTIONAL {
{
<http://dbpedia.org/resource/Coen_brothers>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type> ?type.
?type ?p_type ?o_type.
} UNION {
<http://dbpedia.org/resource/Coen_brothers>
<http://purl.org/dc/terms/subject> ?sub.
?sub ?p_sub ?o_sub.
}
}
}
However they do run very fast on http://lod.openlinksw.com/sparql.
So your settings or hardware might not be balanced for your performance
needs.
Regards,
Jerven
PS.
The query can be further simplified by using the PATH query syntax
CONSTRUCT {<http://dbpedia.org/resource/Coen_brothers> ?p ?o.
?type ?p_type ?o_type.
}
where {
<http://dbpedia.org/resource/Coen_brothers> ?p ?o
OPTIONAL {
<http://dbpedia.org/resource/Coen_brothers>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>|<http://purl.org/dc/terms/subject>
?type.
?type ?p_type ?o_type.
}
}
On 21/03/14 16:54, ghirardi nicola wrote:
> I have this kind of queries that do not perform as expected (transaction
> timeout usually).
> Here an example on dbpedia:
>
> CONSTRUCT { <http://dbpedia.org/resource/Coen_brothers> ?p ?o.
> ?sub ?p_sub ?o_sub.
> ?type ?p_type ?o_type.
> }
> where {
> <http://dbpedia.org/resource/Coen_brothers> ?p ?o
> OPTIONAL {
> <http://dbpedia.org/resource/Coen_brothers>
> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> ?type.
> ?type ?p_type ?o_type.
> }
> OPTIONAL {
> <http://dbpedia.org/resource/Coen_brothers>
> <http://purl.org/dc/terms/subject> ?sub.
> ?sub ?p_sub ?o_sub.
> }
> }
>
> The query answer very fast if I remove one of the optional or the "?p
> ?o" part.
> Is it something expected?
> Can you suggest me another query to get the same response?
> Would use all the properties in separated optional works faster?
>
> Thanks
> Nicola
>
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