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RE: [limit per resource] implementation experience and/or concerns?

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Fri, 17 Apr 2009 10:25:33 +0000
To: Simon Schenk <sschenk@uni-koblenz.de>, Lee Feigenbaum <lee@thefigtrees.net>
CC: SPARQL Working Group <public-rdf-dawg@w3.org>
Message-ID: <B6CF1054FDC8B845BF93A6645D19BEA362D0572D9F@GVW1118EXC.americas.hpqcorp.net>


> -----Original Message-----
> From: public-rdf-dawg-request@w3.org [mailto:public-rdf-dawg-
> request@w3.org] On Behalf Of Simon Schenk
> Sent: 17 April 2009 09:01
> To: Lee Feigenbaum
> Cc: SPARQL Working Group
> Subject: Re: [limit per resource] implementation experience and/or
> concerns?
> 
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> Lee Feigenbaum schrieb:
> >
> > http://www.w3.org/2009/sparql/wiki/Feature:LimitPerResource

> 
> > 1/ does anyone implement this in SPARQL?
> 
> Perhaps Virtuoso and ARQ via subselects?

Yes, it can be done with subselects.  Not as easy as just adding a "limit by resource" to an existing query because it needs the query structured in the right way, but the condition for limiting can be more complex than a simple number.

For ARQ, it can also be done via the client API.  Queries can be aborted when enough resources have been seen, and the conditions can be data-dependent.  Not nice this way but it can be done.

	Andy

> 
> > 2/ does anyone implement this elsewhere (e.g. in SQL)?
> 
> In SQL, this should be possible using subselects, but there is no
> special syntax AFAIC.
> 
> > 3/ on the surface, are there any implementation, specification, or
> other
> > concerns about this feature?
> 
> I think this is a good example for a feature, which might be complicated
> when addressed on its own, but which basically comes for free, when
> combined with another one (subselects).
> 
> Best regards,
> Simon
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Received on Friday, 17 April 2009 10:27:08 GMT

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