sparql query performance

[Paton, Diego]

Hi,

I am working with the Freebase ontology stored in Apache JENA TDB and executing 
queries using Fuseki.

What I want to retrieve is the mID, entity name, description and optionally the 
wikipedia url if present ( I expect to obtain more than 6M of results ). The 
problem is the query takes more than 24h to run.


prefix fb: <http://rdf.freebase.com/ns/>
prefix fn: <http://www.w3.org/2005/xpath-functions#>
select ?mID ?e ?nf ?desc  ?wikipedia_url
where
{
    {
       ?mID fb:type.object.type fb:people.person .
       ?mID fb:type.object.name ?e .
       ?mID fb:common.topic.notable_for ?notab_for .
       ?notab_for fb:common.notable_for.display_name ?nf .
       ?mID fb:common.topic.description ?desc .

       OPTIONAL
       {
          ?mID fb:common.topic.topic_equivalent_webpage ?wikipedia_url .
          FILTER (regex (str(?wikipedia_url), "en.wikipedia", "i") && !regex 
(str(?wikipedia_url), "curid=", "i")) .
       }

       FILTER (langMatches(lang(?e), "en") && langMatches(lang(?nf), "en") && 
langMatches(lang(?desc), "en"))
    }

}

ORDER BY ?mID


This modified query below with optional attribute removed takes 3h.

prefix fb: <http://rdf.freebase.com/ns/>
prefix fn: <http://www.w3.org/2005/xpath-functions#>
select ?mID ?e ?nf ?desc
where
{
    {
       ?mID fb:type.object.type fb:people.person .
       ?mID fb:type.object.name ?e .
       ?mID fb:common.topic.notable_for ?notab_for .
       ?notab_for fb:common.notable_for.display_name ?nf .
       ?mID_raw fb:common.topic.description ?desc .

       FILTER (langMatches(lang(?e), "en") && langMatches(lang(?nf), "en") && 
langMatches(lang(?desc), "en"))
    }
    BIND(REPLACE(str(?mID_raw), "http://rdf.freebase.com/ns/";, "") as ?mID)
}

ORDER BY ?mID

And the modified query below with filter removed in the optional clause takes 
more than 20h ( still running )


prefix fb: <http://rdf.freebase.com/ns/>
prefix fn: <http://www.w3.org/2005/xpath-functions#>
select ?mID ?e ?nf ?desc  ?wikipedia_url
where
{
    {
       ?mID fb:type.object.type fb:people.person .
       ?mID fb:type.object.name ?e .
       ?mID fb:common.topic.notable_for ?notab_for .
       ?notab_for fb:common.notable_for.display_name ?nf .
       ?mID fb:common.topic.description ?desc .

       OPTIONAL
       {
          ?mID fb:common.topic.topic_equivalent_webpage ?wikipedia_url .
       }

       FILTER (langMatches(lang(?e), "en") && langMatches(lang(?nf), "en") && 
langMatches(lang(?desc), "en"))
    }

}

ORDER BY ?mID

Do you have some ideas about how to improve the performance of the first query 
that is the one meets my requirements?

Regards,

Diego.