[jira] [Reopened] (JENA-692) Filter implicit join optimization incorrect

["Rob Vesse (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/JENA-692?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Rob Vesse reopened JENA-692:
----------------------------


Reopening to add missing fix versions

> 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 2.11.0, Jena 2.11.1
>            Reporter: Andy Seaborne
>            Assignee: Rob Vesse
>             Fix For: Jena 2.11.2
>
>         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}}
> Algebra translation:
> {noformat}
> (prefix ((: <http://example.org/>))
>   (filter (= ?a ?b)
>     (union
>       (bgp (triple ?a :p :o1))
>       (bgp (triple ?b :p ?a)))))
> {noformat}
> 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.
> {noformat}
> sparql --set arq:optImplicitJoin=false --file Q.rq --data D.ttl
> {noformat}
> yields the correct answers.



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