On 19/06/12 14:32, Simon Helsen wrote:
Hi guys,
I recently ran into a query which produced a surprising result and it is
not clear to me if I don't understand the spec correctly or whether it is
an ARQ bug. The scenario is that you have a quad store with e.g. 2
identical triples, except that they live in 2 separate graphs. So
if your store contains the following 2 quads
<s1> <p1> <o1> <g1>
<s1> <p1> <o1> <g2>
and you execute the following query with unionDefaultGraph=true
SELECT ?s
WHERE {
?s<p1> <o1>
}
would you not expect two results? It seems that the current ARQ returns
only one result, i.e. by crossing the graphs during unionDefault, it seems
to eliminate duplicates. That is unexpected to me, but perhaps there is
something in the spec I am not aware of
Any thoughts?
Simon
An RDF graph is a set of triples. A set does not have duplicates. How
the graph is formed does not matter; it must behave like a set. So Jena
removes duplicates for a union default graph.
Andy
