Ivan,
I can confirm this - this behavior popped up with 5.0.3: I have no
default graph specified; and SPARQL SELECT * WHERE {?s ?p ?o} yields
no results.
I thought of it was a feature so that users HAVE to specify graphs ;)
With DBpedia, many queries initially didn't specify them, so we were
not aware of the performance issues.
Cheers,
Christian
On Jan 27, 2008, at 12:16 PM, Ivan Mikhailov wrote:
Hello Mikael,
Virtuoso can query unspecified graphs so the issue is probably misused
interface. Can you reproduce this problem by querying via ISQL? If yes
then that is a real (and surprising) problem. If you're using /sparql/
or /isparql/ web service endpoint then please check whether 'default
graph' field contains graph name or empty. When empty then by triple
patterns outside graph ... { ... } will be matched against at all
graphs, when non-empty then they will be restricted to the specified
graph. So if graph is specified but empty then you get nuthing without
graph ?g { ... } and get everything with it.
Best Regards,
Ivan Mikhailov,
OpenLink Software.
On Sun, 2008-01-27 at 11:04 +0100, Mikael Högqvist wrote:
Hi,
I'm using virtuoso 5.0.3 and have run into a problem with queries. I
expect that a query like
select ?s ?p ?o where { ?s ?p ?o }
would return all triples in the store. But it returns nothing,
while this query:
select ?s ?p ?o where { graph ?g {?s ?p ?o }}
returns all the triples. I did not run into this with earlier
versions
of virtuoso and could not find any related configuration setting. All
graphs are indexed by uploading via WebDAV to an rdf_sink-directory.
Is it possible to avoid "graph ?g { ... }"?.
Thanks,
Mikael
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