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From Reto Bachmann-Gmür <r...@apache.org>
Subject Re: [jira] [Commented] (CLEREZZA-761) Implement SPARQL PreParser to support fastlane
Date Wed, 03 Apr 2013 09:45:47 GMT
On Tue, Apr 2, 2013 at 10:45 PM, Hasan Hasan <hasan@trialox.org> wrote:

> Hi Reto,
>
> after studying carefully the description and examples in
> http://www.w3.org/TR/sparql11-query/#rdfDataset
> I think the PreParser should - as you suggested - have a TcProvider to
> return all TripleCollections, in case no FROM NAMED clause is specified in
> the query.
>
> How should we pass the TcProvider to the PreParser? In a separate method,
> e.g.,
>
> public void setTcProvider(TcProvider tcProvider);
>

I think we could have a constructor that takes a TcProvider while the
service would always use TcManager.

Cheers,
Reto

>
> Default TcProvider would be TcManager.
>
> Cheers
> Hasan
>
>
>
> On Tue, Apr 2, 2013 at 12:34 PM, Reto Bachmann-Gmür <reto@apache.org>
> wrote:
>
> > 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 <hasan@trialox.org> 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)
> > > <jira@apache.org>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/%3C51498242.4020809@apache.org%3Ethisshouldreturnall
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.
> > > > If you think it was sent incorrectly, please contact your JIRA
> > > > administrators
> > > > For more information on JIRA, see:
> > > http://www.atlassian.com/software/jira
> > > >
> > >
> >
>

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