- From: Steve Harris <swh@ecs.soton.ac.uk>
- Date: Mon, 17 Dec 2012 08:36:13 +0000
- To: Bob DuCharme <bob@snee.com>
- Cc: public-sparql-dev@w3.org
Bob, I don't think that a URI is any more or less a key than a Literal. They have very similar properties in RDF, the only significant difference is that a Literal can only appear in the object slot, and may have a datatype or language tag. Regards, Steve On 17 Dec 2012, at 03:30, Bob DuCharme wrote: > OK, that makes sense--a URI is inherently a key, so when indexed is easier to look up, while a given literal value is not necessarily, right? > > And congrats on the WG finishing up! > > Bob > > > On 12/16/2012 4:41 PM, Andy Seaborne wrote: >> >> >> On 16/12/12 21:24, Bob DuCharme wrote: >>> Imagine that I have ten million triples, and these are two of them: >>> >>> <http://w> rdfs:label "my literal" . >>> <http://x> <http://y> <http://z> . >>> >>> I got the impression somewhere that this query >>> >>> SELECT ?s WHERE { ?s <http://y> <http://z> } >>> >>> would run faster than this one: >>> >>> SELECT ?s WHERE { ?s rdfs:label "my literal" } >>> >>> Is this true, and if so is it because URIs will always be indexed and >>> literals won't necessarily be? >> >> As far as I know, systems generally index literals - quite important for keys. >> >> Maybe there are many, many 'rdfs:label "my literal"' if it's not a key, which might make a difference, as much because there are more results. >> >>> Or is it all dependent on the >>> implementation? >> >> Yes. >> >> Andy > >
Received on Monday, 17 December 2012 08:36:59 UTC