The motivation of my question was to confirm that occurrences of ?x must
be replaced by bindings in each of the solutions before sending the
query to another service. But I do not found a simpler way to write that
question. That's all.
Thanks!
Daniel
On Tue, 2014-12-23 at 18:49 +0000, Andy Seaborne wrote:
> >> What will be the result of this query?
>
> Empty.
>
> Firstly - the <a> in the query is highly unlikely to be the same <a> as
> the data because the query and data have different base URIs. thsi
> appies to the SERVICE and non-SERVICE cases.
>
> The URI resolution of the query is at parse time so <p> inside the
> SERVICE is the same <p> in the triple pattern
>
> Adding a stable BASE, I get no results with Fuseki2 because the EXISTS
> ?x is substituted from the pattern.
>
> The Fuseki2 log shows a call back of:
>
> Query = SELECT * WHERE { <http://example/b> <http://example/p>
> <http://example/c>}
>
> which I guess is the core of your question?
>
> Andy
>
> ----------------------------
> BASE <http://example/>
> <a> <p> <b> .
> <a> <q> <c> .
> ----------------------------
> BASE <http://example/>
>
> SELECT *
> WHERE {
> { <a> <p> ?x }
> FILTER (
> EXISTS { SERVICE <http://localhost:3030/ds/query> { ?x <p> <c> } }
> )
> }
> ----------------------------
>
>
>
>
> On 23/12/14 15:04, Miguel Bento Alves wrote:
> > Daniel,
> >
> > what is the point?
> >
> > You didn’t clear if you have also a local dataset, but I think that the
> > answer is the same, the result is empty. Why should be different?
> >
> > (in this situations, normally, I test. Seeing is believing :) ).
> >
> > In your dataset, instead of <a> <q> <c> you mean <a> <p> <c>?
> >
> > Miguel
> >
> >
> >
> >> On 23 Dec 2014, at 14:34, Daniel Hernández <[email protected]> wrote:
> >>
> >> Hello,
> >>
> >> Let us consider a service <s> which default dataset contains the default
> >> graph:
> >>
> >> <a> <p> <b> .
> >> <a> <q> <c> .
> >>
> >> Let us consider the following query to be evaluated with the service <s>
> >> described above:
> >>
> >> SELECT *
> >> WHERE { { <a> <p> ?x } FILTER ( EXISTS ( ?x <p> <c> ) ) }
> >>
> >> I suppose that in this case the filter clause is evaluated for each
> >> solution of the graph pattern on the left. Thus, it is evaluated for
> >> {?x:<b>} and {?x:<c>}. Then the clauses will be:
> >>
> >> {?x:<b>} --> EXISTS ( <b> <p> <c> ) (FALSE)
> >> {?x:<c>} --> EXISTS ( <c> <p> <c> ) (FALSE)
> >>
> >> Then, the result of this query will be empty.
> >>
> >> Let us to consider the following query:
> >>
> >> SELECT *
> >> WHERE { { <a> <p> ?x }
> >> FILTER ( EXISTS ( SERVICE <s> { ?x <p> <c> } ) ) }
> >>
> >> What will be the result of this query?
> >>
> >> Regards,
> >> Daniel
> >>
> >
>
