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Re: Queries over multiple graphs

From: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
Date: Tue, 28 Sep 2004 17:28:17 +0100
To: RDF Data Access Working Group <public-rdf-dawg@w3.org>
Message-ID: <20040928162817.GB14835@login.ecs.soton.ac.uk>

On Tue, Sep 28, 2004 at 09:40:35AM -0500, Pat Hayes wrote:
> >On Tue, Sep 28, 2004 at 11:47:05AM +0100, Steve Harris wrote:
> >>
> >> In recent discussions over email and on IRC this morning we hit a
> >> difference of implementation in some RDF storage systems.
> >>
> >> In my system if you load multiple graphs with distinct source information
> >> and the same statement appears in 2 graphs there are two distinct
> >> statements. The same goes for statements that may be inferred by multiple
> >> routes.
> >
> >Discussing this further it appears to be a philosophical difference: does
> >an RDF store hold a single (merged) RDF graph with statements from
> >different sources, or does it hold a set of RDF graphs.
> Surely the right answer is, yes. That is, it could be either. Its up 
> to the owner responsible for maintaining the store to decide. So the 
> QL ought to be able to handle both cases, which I think is the case 
> right now.

I agree, if so we have to agree on wether results are implicitly DISTINT
or if (A, A) == (A) in query results.

- Steve
Received on Tuesday, 28 September 2004 16:28:22 UTC

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