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Posted to dev@jena.apache.org by "Andy Seaborne (JIRA)" <ji...@apache.org> on 2013/12/24 17:41:51 UTC
[jira] [Commented] (JENA-432) Filter optimization messes up when a
nested select is present in the same block
[ https://issues.apache.org/jira/browse/JENA-432?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13856385#comment-13856385 ]
Andy Seaborne commented on JENA-432:
------------------------------------
(reopened to format discussion)
JENA-595 improves the planning for this style of query.
> Filter optimization messes up when a nested select is present in the same block
> -------------------------------------------------------------------------------
>
> Key: JENA-432
> URL: https://issues.apache.org/jira/browse/JENA-432
> Project: Apache Jena
> Issue Type: Bug
> Components: ARQ, Optimizer
> Affects Versions: Jena 2.10.0
> Reporter: Simon Helsen
> Assignee: Andy Seaborne
> Fix For: Jena 2.10.1
>
>
> The following test query:
> {noformat}
> SELECT ?test ?s1
> WHERE {
> ?test ?p1 ?o1.
> FILTER ( ?test = <http://localhost/t1> || ?test = <http://localhost/t2> )
> OPTIONAL {
> SELECT ?s1
> { ?s1 ?p2 ?o2 }
> }
> }
> {noformat}
> produces the following plan:
> {noformat}
> (project (?test ?s1)
> (disjunction
> (table empty)
> (table empty)))
> {noformat}
> Something goes wrong with the FILTER expansion. As a workaround, we observed that the following variation:
> {noformat}
> SELECT ?test ?s1
> WHERE {
> { ?test ?p1 ?o1.
> FILTER ( ?test = <http://localhost/t1> || ?test = <http://localhost/t2> )
> }
> OPTIONAL {
> SELECT ?s1
> { ?s1 ?p2 ?o2 }
> }
> }
> {noformat}
> produces the correct plan:
> {noformat}
> (project (?test ?s1)
> (leftjoin
> (disjunction
> (assign ((?test <http://localhost/t1>))
> (bgp (triple <http://localhost/t1> ?p1 ?o1)))
> (assign ((?test <http://localhost/t2>))
> (bgp (triple <http://localhost/t2> ?p1 ?o1))))
> (project (?s1)
> (bgp (triple ?s1 ?/p2 ?/o2)))))
> {noformat}
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