Hm, I tried flipping the triples around in the query, to:
CONSTRUCT{
?subj ?pred ?obj .
?pred rdfs:domain ?type
}WHERE{
?pred rdfs:domain ?type .
FILTER(?pred = vocab:Objects_Type) .
?subj ?pred ?obj .
}
and I'm not percieving much of a difference in execution time.
I'd love to find some more detailed documentation on how to write
optimal SPARQL queries.
Anyone have any links?
On Oct 16, 9:29 am, donundeen <[EMAIL PROTECTED]> wrote:
> Good Idea, Ill try that for sure.
> But I was never clear on how the order of triples in my where clause
> affect performance. I guess I assumed that the query would be
> optimized for me.
>
> any resources out there that give more details on how to optimize my
> SPARQL queries? I'm running sesame/mulgara.
>
> On Oct 15, 5:01 pm, "Schmitz, Jeffrey A"
>
> <[EMAIL PROTECTED]> wrote:
> > Not to make this a SPARQL message board, but have you tried re-ordering
> > your query? That first line:
>
> > ?subj ?pred ?obj
>
> > is I think going to build your entire model before moving on to the next
> > line. Try something like:
>
> > CONSTRUCT{
> > ?subj ?pred ?obj .
> > ?pred rdfs:domain ?type}WHERE{
>
> > ?pred rdfs:domain ?type .
> > FILTER(?pred = vocab:Objects_Type) .
> > ?subj ?pred ?obj .
>
> > }
> > -----Original Message-----
> > From: donundeen [mailto:[EMAIL PROTECTED]
> > Sent: Wednesday, October 15, 2008 2:52 PM
> > To: TopBraid Composer Users
> > Subject: [tbc-users] Re: Properties as subjects in SPARQL Queries
>
> > 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!
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