Hello Sebastian,
That's a bit weird, but with unspecified graph I should ask first what
indexes are in use?
1073 properties is not so much, so you have less than 1000 graphs of
ontologies and maybe much more graphs other than ontologies. If it's a
case then I'd recommend to experiment with an additional graph that will
contain list of loaded ontologies. So the query may be something like
select distinct ?p where {
graph <ontology-list> { ?g a <loaded-ontology> }
{
graph ?g { ?p a
<http://www.w3.org/1999/02/22-rdf-syntax-ns#Property> .
?p <http://www.w3.org/2000/01/rdf-schema#label> ?l .
?l bif:contains \"'hastag*'\" .
}
UNION
graph ?g { ?p a <http://www.w3.org/1999/02/22-rdf-syntax-ns#Property> .
FILTER(REGEX(STR(?p),'hastag*','i')) .
}
}
}
And even before this experiment I'd measure the speed of
select distinct ?p where {
graph ?g {
?p a <http://www.w3.org/1999/02/22-rdf-syntax-ns#Property> .
?p <http://www.w3.org/2000/01/rdf-schema#label> ?l .
?l bif:contains \"'hastag*'\" .
}
UNION
{ ?p a <http://www.w3.org/1999/02/22-rdf-syntax-ns#Property> .
FILTER(REGEX(STR(?p),'hastag*','i')) .
}
}
in hope that the declaration of a property type and property label are always
in same graph.
Best Regards,
Ivan Mikhailov
OpenLink Software
http://virtuoso.openlinksw.com
On Wed, 2010-03-24 at 18:16 +0100, Sebastian Trüg wrote:
> In my rather simply query parser which allows users to write stuff like
> "hastag:foobar" I am currently using the following query to match
> "hastag" to an actual property (the db contains a bunch of ontologies,
> each loaded in their own graph with a total of 1073 properties in a
> database of about 1099726 triples.)
>
> select distinct ?p where {
> { ?p a <http://www.w3.org/1999/02/22-rdf-syntax-ns#Property> .
> ?p <http://www.w3.org/2000/01/rdf-schema#label> ?l .
> ?l bif:contains \"'hastag*'\" .
> }
> UNION
> { ?p a <http://www.w3.org/1999/02/22-rdf-syntax-ns#Property> .
> FILTER(REGEX(STR(?p),'hastag*','i')) .
> }
> }
>
> It gets me the 2 relevant results:
> p -> <http://www.semanticdesktop.org/ontologies/2007/08/15/nao#hasTag>
> p -> <http://www.semanticdesktop.org/ontologies/2007/11/01/pimo#hasTag>
>
> But the query time is rather long (this is not pure Virtuoso, there is
> some roundtrips from Nepomuk in there): 00:00:02.951
>
> Then I tried to only use regex filters:
>
> select distinct ?p where {
> { ?p a <http://www.w3.org/1999/02/22-rdf-syntax-ns#Property> .
> ?p <http://www.w3.org/2000/01/rdf-schema#label> ?l .
> FILTER(REGEX(STR(?l),'hastag*','i')) .
> }
> UNION
> { ?p a <http://www.w3.org/1999/02/22-rdf-syntax-ns#Property> .
> FILTER(REGEX(STR(?p),'hastag*','i')) .
> }
> }
>
> And suddenly the query time is close to zero: 00:00:00.201
>
> While I am of course happy with a lower query time I am a bit confused
> since I thought the full text query should be much faster than the regex
> filter. My only idea is that filtering over 1023 properties is faster
> than any fulltext query could be. Is that the case?
>
> Cheers,
> Sebastian
>
>
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