W3C home > Mailing lists > Public > semantic-web@w3.org > January 2010

Re: Requirements for a possible "RDF 2.0"

From: Toby Inkster <tai@g5n.co.uk>
Date: Wed, 20 Jan 2010 06:37:22 +0000
To: Steve Harris <steve.harris@garlik.com>
Cc: Danny Ayers <danny.ayers@gmail.com>, jeremy@topquadrant.com, "semantic-web@w3.org" <semantic-web@w3.org>
Message-ID: <1263969442.18556.1304.camel@ophelia2.g5n.co.uk>
On Fri, 2010-01-15 at 22:06 +0000, Steve Harris wrote:
> There is a cost to opening up what can go where in triples. My SPARQL
> engines (and I expect those of others) use this as a source of  
> optimisations. E.g. if some variable appears in the predicate slot,  
> then you know it can only bind to a URI, and you can limit your search
> space. 

I seem to remember that in Virtuoso TP1, the following query:

	SELECT *
	WHERE { 
		?s ?p ?o .
		OPTIONAL { ?o ?q ?v . }
	}

"optimised" things by making the assumption that ?o was not a literal.

:-(

-- 
Toby A Inkster
<mailto:mail@tobyinkster.co.uk>
<http://tobyinkster.co.uk>
Received on Wednesday, 20 January 2010 06:38:13 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 19:48:05 UTC