On 16/02/15 16:59, Stian Soiland-Reyes wrote:
Can you not select that graph ?gCount ?topic programmatically so each
row is another graph URI and its count?
yes - that is what the UNION form does.
There should be no need for
subqueries, and that could in theory stream back - presumably you
probably don't really care about the order here?
UNION streams.
You can use VALUES for matching the ?topic to your fixed list of 1200 URIs.
http://www.w3.org/TR/sparql11-query/#inline-data
Different query - there is a different variable for each count in
Michael's example.
It also needs GROUP BY ...
I've not tested if this would be faster or slower..
Something like:
SELECT ?topic (count(*) as ?count) WHERE {
VALUES ?topic { <http://dbpedia.org/resource/Thomas_Mills_Wood>
<http://sws.geonames.org/2633653/> }
GRAPH ?g { ?s ?p ?topic . }
}
GROUP BY ?topic
That is like the UNION example - one row per topic.
(this seems slower at the virtuoso at http://dbpedia.org/sparql but I
have found Virtuoso doesn't do the streaming back as nicely as Fuseki)
Not surprising - it now can't stream at all without some smarts about
result ordering and GROUP BY or some fairly weird stats (= expensive to
maintain and unlikely to be that useful in many cases) on ?topic / ?g
correlations + execution reordering.
Imagine what if the first and last VALUES hit the same ?g.
Andy
BTW -- do you want out a count of total number of triples across all
graphs that have the ?topic as an object - or a count pr graph that
has ?topic as an object? The query above is the first, but you can
SELECT and GROUP BY ?g as well if you want the second.
