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Re: issue round-up, part 1

From: Andy Seaborne <andy.seaborne@talis.com>
Date: Mon, 17 May 2010 23:05:28 +0100
Message-ID: <4BF1BDA8.50206@talis.com>
To: Lee Feigenbaum <lee@thefigtrees.net>
CC: Olivier Corby <Olivier.Corby@sophia.inria.fr>, SPARQL Working Group <public-rdf-dawg@w3.org>


On 17/05/2010 7:14 PM, Lee Feigenbaum wrote:
> On 5/17/2010 8:03 AM, Olivier Corby wrote:
>> > PROPOSED: Close ISSUE-8 with the consensus that subqueries share the
>> same RDF
>> > dataset as their parent query, and that FROM and FROM NAMED clauses
>> are not
>> > permitted in subqueries.
>>
>> As I said in a previous post, I think there is an interaction between
>> graph and subquery patterns. Does the graph pattern apply to subquery:
>>
>>
>> graph ?g {
>> {select * where { ... }}
>> }
>>
>>
>> I think this is not obvious because we can consider that the subquery
>> creates a fresh new evaluation environment without graph ?g as current
>> graph.
>>
>> This interpretation is based on this case:
>>
>> graph ?g1 {
>> graph ?g2 { }
>> }
>>
>> In this example, graph ?g2 creates a new evaluation environment in which
>> graph ?g2 overloads/hides graph ?g1. We could have the same behavior
>> with subquery.
>>
>> I think that the recommendation should explicit the behavior of graph
>> pattern vs subquery.
>
> I agree. Do you have a preference for the behavior of this construct?

I suggest that the active graph is carried into a subquery.

This makes:

WHERE {
    { something }
    { SELECT * { ... }  }
}

==>

WHERE {
    GRAPH <g> {
      { something }
      { SELECT * { ... }  }
    }
}

retarget the whole of the pattern to match against <g>


    { SELECT * { ... } }
is then a no-op (adds no project or other solution modifier) in terms of 
algebra.

	Andy

>
> Lee
>
>>
>
>
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Received on Monday, 17 May 2010 22:11:08 GMT

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