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Re: Comments on SPARQL 1.1 WD 20091022

From: Leigh Dodds <leigh.dodds@talis.com>
Date: Wed, 27 Jan 2010 13:09:03 +0000
Message-ID: <f323a4471001270509i4af3640ek2673f13f979c951a@mail.gmail.com>
To: Andy Seaborne <andy.seaborne@talis.com>
Cc: public-rdf-dawg-comments <public-rdf-dawg-comments@w3.org>
Hi Andy,

Thanks for the response, it addresses my comments and questions.

Cheers,

L.

2009/11/19 Andy Seaborne <andy.seaborne@talis.com>:
>
> On 24/10/2009 14:09, Leigh Dodds wrote:
> Leigh,
>
> Thank you for your comments.
>
> This first published working draft contains the new areas for query that the
> working group is progressing.  The material will be integrated with the the
> previous version of the query language to produce a single, new document for
> SPARQL 1.1 Query.
>
> Things may be a little rough in this first draft ...
>
> Leigh Dodds wrote:
>  > Hi,
>  >
>  > Here are some personal comments/questions on the 22/10/2009 WD of SPARQL
> 1.1.
>  >
>  > * Example in Section 2. I don't think the project expression conforms
>  > with grammar shown latter in the doc; missing brackets? I know this is
>  > still up for discussion, but thought I'd point it out
>
> Yes - it's not consistent.  The WG had not reached a conclusion on the
> exact syntax at the time of publication.
>
>  > * Section 2, Syntax. re: the note about using FILTER instead of
>  > HAVING. Assuming I'm reading the comment correctly, I think for
>  > readability purposes its better to have a separate keyword (HAVING)
>  > rather than re-use the FILTER keyword. I think its clearer that there
>  > are different constraints (i.e. aggregates allowed or not) on the
>  > expression, and retains similarity with SQL.
>  >
>  > * Section 3. Text above example query is wrong, I think it should
>  > ready "from all the people that Alice knows", not "that know Alice".
>
> Agreed.
>
>  >
>  > * Section 4. What is the rationale for including both a FILTER and a
>  > graph pattern operator for EXISTS/NOT EXISTS? If there are benefits in
>  > terms of expressivity or ease of implementation it would be good to be
>  > able to call these out in the specification.
>
> If the working group decides to allow EXISTS/NOT EXISTS in FILTERs, then
> there will be a example to illustrate the point.
>
>  > * Section 4. The NOT EXISTS and EXISTS graph pattern operators are
>  > described as "applying only to variables defined earlier in the
>  > pattern". What does "earlier" mean if a SPARQL processor can re-order
>  > the statements for optimization purposes? Does use of those operators
>  > have some impact on an implementations ability to do that?
>
> It's loose wording to discuss the scoping of variables.  "earlier" means the
> pattern to the left or above of the NOT EXISTS.
>
>  >
>  > Cheers,
>  >
>  > L.
>
>   Andy
>   on behalf of the SPARQL Working Group
>



-- 
Leigh Dodds
Programme Manager, Talis Platform
Talis
leigh.dodds@talis.com
http://www.talis.com
Received on Wednesday, 27 January 2010 13:09:32 GMT

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