Andy Seaborne created JENA-692:
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Summary: Filter implicit join optimization incorrect
Key: JENA-692
URL: https://issues.apache.org/jira/browse/JENA-692
Project: Apache Jena
Issue Type: Bug
Components: ARQ
Affects Versions: Jena 2.11.1, Jena 2.11.0
Reporter: Andy Seaborne
Attachments: D.ttl, Q.rq
(Starts at 2.11.0; 2.10.* is OK)
The filter implicit join optimization misoptimizes the example - it pushes in
the equality but each arm is missing one of the variables.
{noformat}
PREFIX : <http://example.org/>
SELECT *
{
{ ?a :p :o1 }
UNION
{ ?b :p ?a }
FILTER ( ?a = ?b )
}
{noformat}
The first arm of the UNION does include ?b and so {{( ?a = ?b )}} is false by
being an error with unbound {{?b}}
the optimization creates:
{noformat}
(prefix ((: <http://example.org/>))
(assign ((?a ?b))
(union
(bgp (triple ?b :p :o1))
(bgp (triple ?b :p ?b)))))
{noformat}
which has replaces the {{?a}} with {{?b}} in the first arm.
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