Re: Efficient SPARQL query for RDF collections

[Steve Vestal]

I'm going to generalize this request a bit.  I earlier reported restructuring a query to get from 25 minutes to 90 ms, where I found the "Learning SPARQL" book to be helpful.  Do you know of any more detailed tutorial or guidelines focusing on performance issues, something that goes into a bit more detail about ordering, indexing, interactions between different SPARQL features, and such?

On 1/13/2021 8:28 AM, Mikael Pesonen wrote:

Related to this. This query returns in 70ms

SELECT ?class ?classLabel
WHERE
{
  ?scIntsec rdf:rest*/rdf:first id:308925008 .
  ?scTmp owl:intersectionOf ?scIntsec .
  ?class rdfs:subClassOf ?scTmp.
  ?class skos:prefLabel ?classLabel .
}

but this doesn't finish in 15 minutes (aborted then)

SELECT ?class ?classLabel
WHERE
{
  VALUES ?superClass  {id:308925008 }
  ?scIntsec rdf:rest*/rdf:first ?superClass .
  ?scTmp owl:intersectionOf ?scIntsec .
  ?class rdfs:subClassOf ?scTmp.
  ?class skos:prefLabel ?classLabel .
}

How come they are so different since they do the same thing?


On 15/12/2020 20.30, Andy Seaborne wrote:

On 15/12/2020 14:33, Mikael Pesonen wrote:

Hi,



id:1 rdf:type owl:Class ;

         skos:prefLabel "something"@en .
id:2 rdf:type owl:Class ;

         skos:prefLabel "something else"@en .


... denotes random number of other elements in the list.

SPARQL:

select * where
{

     ?subclass skos:prefLabel ?label .

I am querying subclasses of class (here id:365852007) which belongs to RDF collection like this          rdfs:subClassOf [ owl:intersectionOf ( ... id:365852007 ... ) ]  ;          rdfs:subClassOf [ owl:intersectionOf ( ... id:365852007 ... ) ]  ;      ?subclass rdfs:subClassOf [ owl:intersectionOf /rdf:rest*/rdf:first id:365852007  ] .

Try breaking the pattern up:

    ?Z rdf:rest*/rdf:first id:365852007   .
    ?X owl:intersectionOf ?Z .
    ?subclass rdfs:subClassOf ?X .
    ?subclass rdfs:label ?label .

and use 3.17.0

}




Is there any faster way to get this done?

Thanks!

This is slow (~10 secs) and we need to extend the query to subclasses of the subclasses and so on.

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