- From: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
- Date: Wed, 14 Sep 2005 11:32:34 +0100
- To: RDF Data Access Working Group <public-rdf-dawg@w3.org>
On Wed, Sep 14, 2005 at 10:54:51 +0100, Andy Seaborne wrote: > == Data 1: > :x <p> "z" . > _:a <p> "z" . > > == Query: > SELECT * { ?s <p> ?o } > > == Results > s/:x p/<p> o/"z" > s/_:a p/<p> o/"z" > > And the application wishes to add: > _:a <q> "y" . > > that is, a tripe with the bNode in the abstract syntax form of the grap as > subject. > > This requires both solutions to be returned in the example query. I feel like being pedantic today, so I'l note that the query engine could also, perfectly legally return s/_:zzz p/<p> o/"z" to that query, as bNodes aren't round tripped in SPARQL, c.f. last paragraph of "Templates with Blank Nodes": "The use of variable ?x in the template, which in this example will be bound to blank nodes (which have labels _:a and _:b in the data) causes different blank node labels (_:v1 and _:v2) as shown by the results." so at the very least this usecase requires knowledge of how bnodes are handled in results in the implementation. - Steve
Received on Wednesday, 14 September 2005 10:33:09 UTC