well, ultimately I'd export all those triples, hence the construct.
hmm, maybe I'm confused, but a predicate can be the subject of a
triple, like
?predicate rdfs:domain ?domain
this query works:
CONSTRUCT{
?subj ?pred ?obj .
?pred rdfs:domain ?type
}WHERE{
?subj ?pred ?obj .
?pred rdfs:domain ?type .
FILTER(?pred = vocab:Objects_Type)
}
but takes forever to return.
Is there a reason these kinds of queries are so slow? it just seems to
perform significantly worse than similar queries that don't use
predicates as subjects.
thanks
don
On Oct 15, 2:48 pm, Scott Henninger <[EMAIL PROTECTED]>
wrote:
> Don; I am not clear on what you mean by "...whenever I try to use a
> predicate as the subject of a query". SPARQL uses triple patterns to
> match a graph, such as:
> ?subj ?pred ?obj
>
> If you then try in the same query to do
> ?pred ?x ?y
>
> ...you won't find a match because the first pattern bound ?pred to a
> predicate and the second is looking for ?pred as a subject of a
> triple.
>
> So for example, if you had the following:
> :xyz vocab:ObjTitles_Title :abc
> :xyz vocab:ObjTitles_Title :uvw
>
> then a query with the following:
> ?obj ?outPred ?outObj .
>
> The result would be bound in two result sets:
> ?obj=:xyz ?outPred=vocab:ObjTitles_Title ?outObj=:abc
> ?obj=:xyz ?outPred=vocab:ObjTitles_Title ?outObj=:uvw
>
> If you tried a query with the following:
> ?obj ?outPred ?outObj .
> ?outPred ?x ?outPredProps .
>
> It won't match anything because vocab:ObjTitles_Title is defined in
> the data as a predicate and cannot appear as a subject or an object.
>
> If that's not the issue you are getting at, then maybe some sample
> data would help. I'm also not clear what purpose the CONSTRUCT
> triples are serving, given that you seem to just want to get data, not
> map it to another structure.
>
> -- Scott
>
> On Oct 15, 12:27 pm, donundeen <[EMAIL PROTECTED]> wrote:
>
> > Hi,
> > I'm trying to do some queries, to gather all data "around" some
> > resource.
> > Basically, questions like "Get me all triples pointing in and out of
> > this resource, and all triples connected to THOSE resources."
>
> > So I put together a query like:
> > CONSTRUCT {
> > ?obj ?outPred ?outObj .
> > ?inObj ?inPred ?obj .} WHERE {
>
> > ?x vocab:ObjTitles_Title ?objTitle .
> > FILTER fn:matches(?objTitle, 'madame x' ,'i') .
> > ?x vocab:ObjTitles_ObjectID ?obj .
> > ?obj ?outPred ?outObj .
> > ?inObj ?inPred ?obj .
>
> > }
>
> > That query works fine.
> > However, Now I want to do two additional things:
> > 1. go an additional hop out, in either direction (ie, get all triples
> > connected to the ?outObj and ?inObj resources)
> > 2. Get all triples connected to the PREDICATES themselves. (this would
> > usually be ontological information, like domain, subproperty, etc)
>
> > Attempting to add either 1 or 2, leads to queries that don't seem to
> > ever complete.
> > Here's the query I have now:
>
> > CONSTRUCT {
> > ?obj ?outPred ?outObj .
> > ?inObj ?inPred ?obj .
> > ?inPred ?y ?inPredProps .
> > ?outPred ?x ?outPredProps .
> > ?outObj ?outOutPred ?outOutObj .
> > ?inObj ?inOutPred ?inOutObj .} WHERE {
>
> > ?x vocab:ObjTitles_Title ?objTitle .
> > FILTER fn:matches(?objTitle, 'madame x' ,'i') .
> > ?x vocab:ObjTitles_ObjectID ?obj .
> > ?obj ?outPred ?outObj .
> > ?inObj ?inPred ?obj .
> > OPTIONAL {?outPred ?x ?outPredProps}.
> > OPTIONAL {?inPred ?y ?inPredProps } .
> > OPTIONAL { ?outObj ?outOutPred ?outOutObj } .
> > OPTIONAL { ?inObj ?inOutPred ?inOutObj . }
>
> > }
>
> > I'm wondering if my querying is creating loops somehow, and that's why
> > trying to go extra hops on the graph is making the query fail to
> > complete?
> > Or is it just that there's too much data to sift through?
>
> > Also, I seem to notice a big reduction in performance whenever I try
> > to use a predicate as the subject in a query. Is there a difference
> > internally (Sesame/Mulgara) in how predicates are indexed, that would
> > be the cause of it?
>
> > perhaps there's a better approach to this problem, which is that I
> > want to extract a connected graph, centered around some node or group
> > of nodes.
>
> > thanks!
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"TopBraid Composer Users" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/topbraid-composer-users?hl=en
-~----------~----~----~----~------~----~------~--~---
