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https://issues.apache.org/jira/browse/JENA-875?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14299798#comment-14299798
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ASF subversion and git services commented on JENA-875:
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Commit e2ec1f745fcc83fcfb832315b7cf6fc1309ee084 in jena's branch
refs/heads/master from [~andy.seaborne]
[ https://git-wip-us.apache.org/repos/asf?p=jena.git;h=e2ec1f7 ]
Place filters around extend/assign when introduced variables allow it.
JENA-875
> Additional optimization for BIND :
> -----------------------------------
>
> Key: JENA-875
> URL: https://issues.apache.org/jira/browse/JENA-875
> Project: Apache Jena
> Issue Type: Bug
> Components: ARQ
> Affects Versions: Jena 2.12.1
> Reporter: Andy Seaborne
> Assignee: Andy Seaborne
> Priority: Minor
> Fix For: Jena 2.12.2
>
>
> This is split out from investigation of JENA-874. It is not the cause but was
> noticed writing the simplified test case.
> With {{(extend))}, the filter-placement optimization can apply filter
> expressions directly when the {{(extend)}} introduces variables.
> Currently, the filter-placement optimization only covers expressions pushed
> inside the {{(extend)}}.
> Example:
> Input:
> {noformat}
> (filter (= ?x 123)
> (distinct
> (extend ((?x 123))
> (bgp (triple ?s ?p ?o)))))
> {noformat}
> The {{distinct}} is just some operation that is betwen the {{(extend)}} nad
> the outer most level.
> Otherwise, the difference does not show up.
> Current optimization:
> {noformat}
> (filter (= ?x 123)
> (distinct
> (extend ((?x 123))
> (bgp (triple ?s ?p ?o)))))
> {noformat}
> The filter is not placed around the {{(extend)}} but bubbles further up.
> With the improved optimization:
> {noformat}
> (distinct
> (filter (= ?x 123)
> (extend ((?x 123))
> (bgp (triple ?s ?p ?o)))))
> {noformat}
> The filter is placed around the {{(extend)}} at the lowest point possible
> point.
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