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https://issues.apache.org/jira/browse/JENA-2107?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17346772#comment-17346772
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Lorenz Bühmann commented on JENA-2107:
--------------------------------------
Some numbers:
#Triples = {{50,367}}
the shape of the data is:
* 100 nodes with a directed connection to each other, i.e. 9900 triples of
<v1,e,v2>
* for each connection we have 4 triples making statements about the connection
* plus some other data about the nodes themselves
a simplified query on the data executed is
{code:sql}
SELECT (count(*) as ?cnt) {
?src <p> ?target .
<<?src <p> ?target>> <p1> ?val1 ;
<p2> ?val2
}{code}
h4. Runtimes:
{code:java}
sparql --time --repeat 2,5 --data ... --query ...{code}
h5. Jena 4.0.0
Time: 81.749 sec
Total time: 403.872 sec for repeat count of 5 : average: 80.774
h5. Jena 4.1.0-SNAPSHOT with fix
Time: 0.039 sec
Total time: 0.422 sec for repeat count of 5 : average: 0.084
> RDF Star performance issue with non-concrete node triples
> ---------------------------------------------------------
>
> Key: JENA-2107
> URL: https://issues.apache.org/jira/browse/JENA-2107
> Project: Apache Jena
> Issue Type: Improvement
> Components: ARQ
> Affects Versions: Jena 3.17.0, Jena 4.0.0
> Reporter: Lorenz Bühmann
> Priority: Critical
> Fix For: Jena 4.1.0
>
>
> the following graph pattern is not evaluated efficiently (results in
> full-scan per binding) because the second triple pattern doesn't take
> advantage of the bindings generated by evaluation of the first one:
> {code:java}
> ?s <p> ?o .
> << ?s <p> ?o >> <p2> ?v .
> {code}
> A possible fix would be to adapt the method {{rdfStarTripleSub()}} in class
>
> [SolverRX3.java|https://github.com/apache/jena/blob/2efff8a00b4ffa82751cf46c8a3fed84b6ff3090/jena-arq/src/main/java/org/apache/jena/sparql/engine/main/solver/SolverRX3.java#L63-L71]
> by changing the beginning to
> {code:java}
> private static Iterator<Binding> rdfStarTripleSub(Binding input, Triple
> xPattern, ExecutionContext execCxt) {
> Triple tPattern = Substitute.substitute(xPattern, input);
> {code}
> We went from 75s for a very small dataset (50k triples) to near instant
> response times.
> If this fix is correct and doesn't break anything, it might be the same way
> to fix for its quads counterpart in {{SolverRX4}} class.
>
> Note, for tdbquery, this seems to be evaluated at a different place? At
> least, we couldn't find any performance improvement, it's still horribly slow.
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