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https://issues.apache.org/jira/browse/JENA-2332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17548265#comment-17548265
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Claus Stadler commented on JENA-2332:
-------------------------------------
It's good that the proper standard behavior is now clarified and adhered to.
But this change breaks existing queries for me and probably others as well.
Currently with this fix I see no way to migrate those queries; so right now for
me it feels like that with this report I shot myself in the foot or locked
myself out with the keys still inside :)
What would be needed is some controlled way to get the "wrong" behavior.
Without any syntax extensions I was thinking about using SERVICE <correlate:>
(or SERVICE <linear:>) as a syntactic marker to force a linear join such that
e.g. JoinClassifier.isLinear returns true.
Or maybe you have a better idea?
> Bad optimization transform when modifers used in SERVICE
> --------------------------------------------------------
>
> Key: JENA-2332
> URL: https://issues.apache.org/jira/browse/JENA-2332
> Project: Apache Jena
> Issue Type: Bug
> Components: ARQ
> Affects Versions: Jena 4.5.0
> Reporter: Andy Seaborne
> Assignee: Andy Seaborne
> Priority: Major
> Fix For: Jena 4.6.0
>
>
> Report: https://lists.apache.org/thread/87wgds6c43j88829bscx4xkwsgcgq58p
> {noformat}
> SELECT * {
> SERVICE <https://dbpedia.org/sparql> { SELECT * { ?s a
> <http://dbpedia.org/ontology/MusicalArtist> } LIMIT 5 }
> SERVICE <https://dbpedia.org/sparql> { SELECT * { ?s
> <http://www.w3.org/2000/01/rdf-schema#label> ?x } LIMIT 1 }
> }
> {noformat}
> produces
> {noformat}
> (sequence
> (service <https://dbpedia.org/sparql>
> (slice _ 5
> (bgp (triple ?s <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
> <http://dbpedia.org/ontology/MusicalArtist>))))
> (service <https://dbpedia.org/sparql>
> (slice _ 1
> (bgp (triple ?s <http://www.w3.org/2000/01/rdf-schema#label> ?x)))))
> {noformat}
> but this query can't be transformed because of {{?s}}.
> It needs to remain as a join.
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