Hi,
The query SELECT DISTINCT ?g { GRAPH ?g { ?s ?p ?o } } can obviously only
be answered correctly by a sparql engine that knows about all the available
graphs. As typically not all graphs are provided by the same provider this
means the query has to be slow laned.
If the pre parser returns only the default graph as this is currently the
case:
zz>spp.getReferredGraphs("SELECT DISTINCT ?g { GRAPH ?g { ?s ?p ?o } }",new
UriRef("urn:x-localinstance:/content.graph"))
res0: java.util.Set[org.apache.clerezza.rdf.core.UriRef] =
[<urn:x-localinstance:/content.graph>]
The query would be fastlaned to the TcProvider providing the Graph
<urn:x-localinstance:/content.graph> which potentially knows about none of
the other graphs.
So I think either the preparser has the TcManager and returns all the
TripleCollections or it returns a special value to tell the caller that the
set of affected graphs cannot be limited (return null).
Currently clerezza correctly returns all triple collections:
zz>val q = qp.parse("SELECT DISTINCT ?g { GRAPH ?g { ?s ?p ?o } }")
q: org.apache.clerezza.rdf.core.sparql.query.Query =
SELECT DISTINCT
?g
WHERE
{ GRAPH ?g { ?s ?p ?o .
} }
zz>val r = tcm.executeSparqlQuery(q.asInstanceOf[SelectQuery], new
SimpleMGraph)
r: org.apache.clerezza.rdf.core.sparql.ResultSet =
org.apache.clerezza.rdf.jena.sparql.ResultSetWrapper@b0d2ffd
zz>r.next
res5: org.apache.clerezza.rdf.core.sparql.SolutionMapping =
{org.apache.clerezza.rdf.core.sparql.query.Variable@67
=<urn:x-localinstance:/tbox.graph>}
zz>r.next
res6: org.apache.clerezza.rdf.core.sparql.SolutionMapping =
{org.apache.clerezza.rdf.core.sparql.query.Variable@67
=<urn:x-localinstance:/config.graph>}
zz>r.next
res7: org.apache.clerezza.rdf.core.sparql.SolutionMapping =
{org.apache.clerezza.rdf.core.sparql.query.Variable@67
=<urn:x-localinstance:/content.graph>}
zz>r.next
res8: org.apache.clerezza.rdf.core.sparql.SolutionMapping =
{org.apache.clerezza.rdf.core.sparql.query.Variable@67
=<urn:x-localinstance:/documentation.graph>}
zz>r.next
res9: org.apache.clerezza.rdf.core.sparql.SolutionMapping =
{org.apache.clerezza.rdf.core.sparql.query.Variable@67
=<urn:x-localinstance:/web-resources-cache.graph1364897492157>}
zz>r.next
res10: org.apache.clerezza.rdf.core.sparql.SolutionMapping =
{org.apache.clerezza.rdf.core.sparql.query.Variable@67
=<urn:x-localinstance:/graph-access.graph>}
zz>r.next
res11: org.apache.clerezza.rdf.core.sparql.SolutionMapping =
{org.apache.clerezza.rdf.core.sparql.query.Variable@67
=<urn:x-localinstance:/web-resources.graph>}
zz>r.next
res12: org.apache.clerezza.rdf.core.sparql.SolutionMapping =
{org.apache.clerezza.rdf.core.sparql.query.Variable@67
=<urn:x-localinstance:/system.grap
Cheers,
Reto
On Tue, Apr 2, 2013 at 8:10 AM, Hasan Hasan <[email protected]> wrote:
> Hi Reto, all
>
> Two issues here:
>
> First the query: SELECT DISTINCT ?g { GRAPH ?g { ?s ?p ?o } }
> does not specify NAMED graphs.
> If the query is as follows
> SELECT DISTINCT ?g FROM NAMED http://example.org/g1 { GRAPH ?g { ?s ?p ?o
> }
> }
> then the engine will return http://example.org/g1
> because the clause GRAPH refers only NAMED graphs as mentioned by Andy
>
> Second the parser: I think the parser needs not know about TcManager or
> other providers in this case, because
> the named graphs are all specified in the query.
>
> Cheers
> Hasan
>
>
>
> On Fri, Mar 29, 2013 at 1:47 PM, Reto Bachmann-Gmür (JIRA)
> <[email protected]>wrote:
>
> >
> > [
> >
> https://issues.apache.org/jira/browse/CLEREZZA-761?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13617295#comment-13617295
> ]
> >
> > Reto Bachmann-Gmür commented on CLEREZZA-761:
> > ---------------------------------------------
> >
> > zz>import org.apache.clerezza.rdf.core.sparql._
> > import org.apache.clerezza.rdf.core.sparql._
> > zz>val spp = $[SparqlPreParser]
> > spp: org.apache.clerezza.rdf.core.sparql.SparqlPreParser =
> > org.apache.clerezza.rdf.core.sparql.SparqlPreParser@3aa78e7a
> > zz>spp.getReferredGraphs("SELECT DISTINCT ?g { GRAPH ?g { ?s ?p ?o } }",
> > new UriRef("urn:x-localinstance:/content.graph"))
> > res0: java.util.Set[org.apache.clerezza.rdf.core.UriRef] =
> > [<urn:x-localinstance:/content.graph>]
> > zz>
> >
> > As discussed in
> >
> http://mail-archives.apache.org/mod_mbox/clerezza-dev/201303.mbox/%[email protected]%3Ethisshould
> return all the graphs in the dataset. I think that
> > SParqlPreParser being a service it could consider by default TcManager
> > being the dataset, but it probably should also have a method that takes
> any
> > TcProvider as dataset and return it's triple collections.
> >
> > > Implement SPARQL PreParser to support fastlane
> > > ----------------------------------------------
> > >
> > > Key: CLEREZZA-761
> > > URL:
> https://issues.apache.org/jira/browse/CLEREZZA-761
> > > Project: Clerezza
> > > Issue Type: New Feature
> > > Reporter: Hasan
> > > Assignee: Hasan
> > >
> > > The purpose is to have a class with a method to obtain referred graphs
> > in a SPARQL Query or SPARQL Update
> >
> > --
> > This message is automatically generated by JIRA.
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> > administrators
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> >
>
