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https://issues.apache.org/jira/browse/JENA-1275?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Andy Seaborne resolved JENA-1275.
---------------------------------
Resolution: Fixed
Fix Version/s: Jena 3.2.0
> TransformScopeRename does the wrong thing with FILTER NOT EXISTS
> ----------------------------------------------------------------
>
> Key: JENA-1275
> URL: https://issues.apache.org/jira/browse/JENA-1275
> Project: Apache Jena
> Issue Type: Bug
> Components: ARQ
> Affects Versions: Jena 3.1.1
> Reporter: Rob Vesse
> Assignee: Andy Seaborne
> Fix For: Jena 3.2.0
>
>
> I have produced the following minimal query from an originally much larger
> query. When the optimise is applied to this it incorrectly double renames the
> variables inside of the {{FILTER NOT EXISTS}} clause leading to incorrect
> algebra.
> Query:
> {noformat}
> SELECT ?triangles ?openTriplets
> {
> {
> #subQ2: calculate #open-triplets
> SELECT (COUNT(?x) as ?openTriplets)
> WHERE {
> ?x ?a ?y .
> ?y ?b ?z .
> FILTER NOT EXISTS {?z ?c ?x}
> }
> }
> }
> {noformat}
> Output:
> {noformat}
> (project (?triangles ?openTriplets)
> (project (?openTriplets)
> (extend ((?openTriplets ?/.0))
> (group () ((?/.0 (count ?/x)))
> (filter (notexists
> (quadpattern (quad <urn:x-arq:DefaultGraphNode> ?//z ?//c
> ?//x)))
> (quadpattern
> (quad <urn:x-arq:DefaultGraphNode> ?/x ?/a ?/y)
> (quad <urn:x-arq:DefaultGraphNode> ?/y ?/b ?/z)
> ))))))
> {noformat}
> Note that we apply the quad transformation prior to applying the optimiser.
> Strangely enough I cannot reproduce the problem using pure Jena command line
> tools i.e. {{qparse}} although I note from the code that it applies quad
> transformation after applying optimisation. This suggests that it is a bug in
> how TransformScopeRename applies to quad form algebra.
> I can reproduce it with a unit test like so:
> {noformat}
> @Test
> public void filter_not_exists_scoping_03() {
> //@formatter:off
> Op orig = SSE.parseOp(StrUtils.strjoinNL("(project (?triangles
> ?openTriplets)",
> " (project (?openTriplets)",
> " (extend ((?openTriplets ?.0))",
> " (group () ((?.0 (count ?x)))",
> " (filter (notexists",
> " (quadpattern (quad
> <urn:x-arq:DefaultGraphNode> ?z ?c ?x)))",
> " (quadpattern",
> " (quad
> <urn:x-arq:DefaultGraphNode> ?x ?a ?y)",
> " (quad
> <urn:x-arq:DefaultGraphNode> ?y ?b ?z)",
> " ))))))"));
> Op expected = SSE.parseOp(StrUtils.strjoinNL("(project (?triangles
> ?openTriplets)",
> " (project (?openTriplets)",
> " (extend ((?openTriplets ?/.0))",
> " (group () ((?/.0 (count ?/x)))",
> " (filter (notexists",
> " (quadpattern (quad
> <urn:x-arq:DefaultGraphNode> ?/z ?/c ?/x)))",
> " (quadpattern",
> " (quad <urn:x-arq:DefaultGraphNode> ?/x ?/a ?/y)",
> " (quad <urn:x-arq:DefaultGraphNode> ?/y ?/b ?/z)",
> " ))))))"));
> //@formatter:on
>
> Op transformed = TransformScopeRename.transform(orig);
>
> Assert.assertEquals(transformed, expected);
> }
>
> @Test
> public void filter_not_exists_scoping_04() {
> //@formatter:off
> Op orig = SSE.parseOp(StrUtils.strjoinNL(
> " (project (?openTriplets)",
> " (extend ((?openTriplets ?.0))",
> " (group () ((?.0 (count ?x)))",
> " (filter (notexists",
> " (quadpattern (quad
> <urn:x-arq:DefaultGraphNode> ?z ?c ?x)))",
> " (quadpattern",
> " (quad
> <urn:x-arq:DefaultGraphNode> ?x ?a ?y)",
> " (quad
> <urn:x-arq:DefaultGraphNode> ?y ?b ?z)",
> " )))))"));
> Op expected = SSE.parseOp(StrUtils.strjoinNL(
> " (project (?openTriplets)",
> " (extend ((?openTriplets ?.0))",
> " (group () ((?.0 (count ?x)))",
> " (filter (notexists",
> " (quadpattern (quad
> <urn:x-arq:DefaultGraphNode> ?z ?c ?x)))",
> " (quadpattern",
> " (quad <urn:x-arq:DefaultGraphNode> ?x ?a ?y)",
> " (quad <urn:x-arq:DefaultGraphNode> ?y ?b ?z)",
> " )))))"));
> //@formatter:on
>
> Op transformed = TransformScopeRename.transform(orig);
>
> Assert.assertEquals(transformed, expected);
> }
> {noformat}
> The first test fails while the second passes. This implies that you need 2
> levels of projection to hit the bug.
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