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Re: DB-5 response

From: Steve Harris <steve.harris@garlik.com>
Date: Tue, 20 Dec 2011 09:40:40 +0000
Cc: SPARQL Working Group <public-rdf-dawg@w3.org>
Message-Id: <6F58AE67-8F61-443F-9CBA-5B6D7069C012@garlik.com>
To: Paul Gearon <pgearon@revelytix.com>
Looks fine to me, with one minor note (probably not worth adding to the reply, but it struct me when reading it):

“While queries operate on a dataset that is defined as a merge of multiple graphs, any updates must necessarily modify a single graph at a time. So it is not possible to state that updates operate on RDF Datasets.

While a single INSERT or DELETE template may refer to multiple graphs, the triples being specified are always for individual graphs. So to remove the same triples from graphs <foo> and <bar> there is no way to do it with a single pattern in a template, but rather both graphs must be mentioned explicitly with that template. ie.:

DELETE { GRAPH <foo> { ... } GRAPH <bar> { ... }} …”

There is some possible overlap with "default graph" behaviour relating to this comment.

In 4store (and 5store I believe) operations on the "default graph" will affect all graphs, as the default graph is the RDF Union of the named graphs, so:

DELETE {
  ?s a <Class>
}
WHERE {
  ?s a <Class>
}

will affect all named graphs including a triple matching the pattern.

I don't know if this is compatible with what's written in the document, but it appears to be what users expect.

If other systems have this behaviour then it might be worth mentioning, but probably not.

- Steve

On 19 Dec 2011, at 22:56, Paul Gearon wrote:

> Hi,
> 
> In response to DB-5:
> http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2011Jul/0017
> 
> I've created:
> http://www.w3.org/2009/sparql/wiki/CommentResponse:DB-5
> 
> In point 8 there were some comments on the lack of definition of how
> to define the URI of a graph store. I seem to recall that when this
> was mentioned a few weeks ago that it had been intentionally specified
> at its current level. However, since the comments refer to the service
> description and protocol documents, I'd appreciate any input from Greg
> or Chimezie.
> 
> Also, David suggested that the text in section 3.1.3 may benefit from
> having a decision tree to describe the currently operating dataset
> (depending on the use of WITH, USING, and GRAPH). I have not done
> this, but would appreciate any feedback as to whether this ought to be
> included.
> 
> The changes mentioned in the response are all in the Overview.xml in CVS.
> 
> Regards,
> Paul Gearon
> 

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Received on Tuesday, 20 December 2011 09:41:12 GMT

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