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https://issues.apache.org/jira/browse/JENA-1468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16343538#comment-16343538
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ASF GitHub Bot commented on JENA-1468:
--------------------------------------
Github user afs commented on the issue:
https://github.com/apache/jena/pull/345
@RickMoynihan : thanks for looking at it.
Merge : soon, because you provide independent checking. It will then be in
the daily development build but that is not a formal release.
Release : this depends on people-time, and realistically, we can't make
solid timelines. We do run "releasable master" means that the master branch is
releasable most of the time so the dev builds are realistic.
The general project hope is every 3-4 months, though we had an out-of-step
release at 3.6.0. That is not a commitment though!
> Empty VALUES clauses lose variable bindings when compiled to a SSE
> ------------------------------------------------------------------
>
> Key: JENA-1468
> URL: https://issues.apache.org/jira/browse/JENA-1468
> Project: Apache Jena
> Issue Type: Bug
> Components: ARQ
> Affects Versions: Jena 3.1.1, Jena 3.2.0, Jena 3.3.0, Jena 3.4.0, Jena
> 3.5.0, Jena 3.6.0
> Reporter: Rick
> Priority: Major
> Labels: SPARQL, sse
>
> Given a SPARQL query like this:
> SELECT ?foo WHERE {
> ?foo ?bar ?baz . # Not essential for problem just to show we can't
> optimise it away.
> VALUES ?foo { }
> }
> If you compile it into an SSE with something like this:
> {{Algebra.compile(QueryFactory.create("SELECT ?foo WHERE \{ ?foo ?bar ?baz .
> VALUES ?foo { }}"));}}
> You end up with a semantically different SSE:
> {{(project (?foo)}}
> {{ (join}}
> {{ (bgp (triple ?foo ?bar ?baz))}}
> {{ (table empty)))}}
> Note how "(table empty)" has lost the ?foo binding, which means that this
> query returns all results for ?foo, where it should return no results.
> I'm not sure how this query should be expressed in SSE form I'd suggest:
> {{(table (vars ?foo) empty)}}
> Though currently this will get simplified in [code like
> this|https://github.com/apache/jena/blob/94eb3fc99ba1ff3991a629fffa6e6cf8b52d6c53/jena-arq/src/main/java/org/apache/jena/sparql/sse/builders/BuilderTable.java#L55-L64]
> into an EmptyTable if you do something like:
> {{BuilderTable.build(Item.createList((SSE.parse("(table (vars ?foo)
> empty)")));}}
> Additionally it appears quite a bit of code carries through this assumption
> that an [empty table will never have a
> binding|https://github.com/apache/jena/blob/94eb3fc99ba1ff3991a629fffa6e6cf8b52d6c53/jena-arq/src/main/java/org/apache/jena/sparql/algebra/table/TableEmpty.java#L57].
> As far as I can tell this issue effects many prior versions of JENA including
> 3.6.0.
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