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https://issues.apache.org/jira/browse/JENA-809?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14191777#comment-14191777
]
Andy Seaborne commented on JENA-809:
------------------------------------
There is modification in-p-lace going on: printing the input op before and
after shows a change.
{noformat}
public static void main(String... argv) throws Exception {
String x = "SELECT * { SERVICE <> { BIND(1 AS ?foo) BIND(2 AS ?bar) }
}" ;
Query query = QueryFactory.create(x) ;
Op op = Algebra.compile(query) ;
System.out.println(op) ;
Transform t = new TransformExtendCombine() ;
Op op2 = Transformer.transformSkipService(t, op) ;
System.out.println(op) ;
}
{noformat}
yields
{noformat}
(service <file:///home/afs/Projects/X/>
(extend ((?bar 2))
(extend ((?foo 1))
(table unit))))
(service <file:///home/afs/Projects/X/>
(extend ((?bar 2))
(extend ((?foo 1) (?bar 2))
(table unit))))
{noformat}
> TransformExtendCombine breaks BINDs inside SERVICE
> --------------------------------------------------
>
> Key: JENA-809
> URL: https://issues.apache.org/jira/browse/JENA-809
> Project: Apache Jena
> Issue Type: Bug
> Components: ARQ
> Affects Versions: Jena 2.12.1
> Reporter: Eetu Mäkelä
>
> Optimization breaks BIND expressions in some situations since
> TransformExtendCombine was enabled in commit
> 4e5fe9a20d1531430ab96cb2ab9694aed9a9538b (culprit found using git bisect). I
> don't know exactly when or why this happens, but I hit upon this while using
> SERVICE. I've been able to create the following minimal example.
> For the query:
> {code}
> SELECT * {
> SERVICE <> {
> BIND(1 AS ?foo)
> BIND(2 AS ?bar)
> }
> }
> {code}
> qparse --explain for 2.12.0 returns:
> {code}
> (service <file:///home/jiemakel/qf>
> (extend ((?foo 1) (?bar 2))
> (table unit)))
> {code}
> which works fine, while for 2.12.1 it returns:
> {code}
> (service <file:///home/jiemakel/qf>
> (extend ((?bar 2))
> (extend ((?foo 1) (?bar 2))
> (table unit))))
> {code}
> which binds ?bar twice, and fails with {{BIND: Variable used when already
> in-scope: ?bar in BIND(2 AS ?bar)}}
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