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Posted to dev@jena.apache.org by "Andy Seaborne (JIRA)" <ji...@apache.org> on 2013/09/19 23:58:52 UTC
[jira] [Commented] (JENA-535) Algebra.toQuadForm() does not
transform Expressions in Optional clauses
[ https://issues.apache.org/jira/browse/JENA-535?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13772373#comment-13772373 ]
Andy Seaborne commented on JENA-535:
------------------------------------
It does look like the quad transformation is not visiting the expression of OpLeftJoin. Do you have a suggested patch?
Oddly, if the expression is optimized first, the transformation is done correctly because the expression, in this case, becomes the left side of a `(conditional)`.
> Algebra.toQuadForm() does not transform Expressions in Optional clauses
> -----------------------------------------------------------------------
>
> Key: JENA-535
> URL: https://issues.apache.org/jira/browse/JENA-535
> Project: Apache Jena
> Issue Type: Bug
> Components: ARQ
> Affects Versions: Jena 2.11.0
> Reporter: Tracy Hartford
>
> Our internal testing has flagged up a failure in 2.11.0 in Algebra.toQuadForm() when applied to expressions within an OPTIONAL clause.
> The query in question is as follows:
> {noformat}
> SELECT *
> WHERE
> { ?s ?p ?o
> OPTIONAL
> {
> FILTER NOT EXISTS {?s ?p ?o }
> }
> }
> {noformat}
> The algebra before calling Algebra.toQuadForm() is as follows:
> {noformat}
> (leftjoin
> (bgp (triple ?s ?p ?o))
> (table unit)
> (notexists (bgp (triple ?s ?p ?o))))
> {noformat}
> The expected algebra is as follows:
> {noformat}
> (leftjoin
> (quadpattern (quad <urn:x-arq:DefaultGraphNode> ?s ?p ?o))
> (table unit)
> (notexists (quadpattern (quad <urn:x-arq:DefaultGraphNode> ?s ?p ?o))))
> {noformat}
> The resulting algebra is as follows:
> {noformat}
> (leftjoin
> (quadpattern (quad <urn:x-arq:DefaultGraphNode> ?s ?p ?o))
> (table unit)
> (notexists (bgp (triple ?s ?p ?o))))
> {noformat}
> It appears that the Transform Walkers visit the left and right Ops of the OpLeftJoin but not the ExprList that contains the E_NotExists.
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