[jira] [Resolved] (JENA-2335) Query -> Algebra -> Query not equivalent in case of a BIND not in the result vars

["Andy Seaborne (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/JENA-2335?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andy Seaborne resolved JENA-2335.
---------------------------------
    Fix Version/s: Jena 4.6.0
         Assignee: Andy Seaborne
       Resolution: Delivered

> Query -> Algebra -> Query not equivalent in case of a BIND not in the result vars
> ---------------------------------------------------------------------------------
>
>                 Key: JENA-2335
>                 URL: https://issues.apache.org/jira/browse/JENA-2335
>             Project: Apache Jena
>          Issue Type: Bug
>          Components: ARQ, Optimizer
>    Affects Versions: Jena 4.5.0
>            Reporter: Jan Martin Keil
>            Assignee: Andy Seaborne
>            Priority: Major
>             Fix For: Jena 4.6.0
>
>
> Converting a query into algebra and back results in a not equivalent query, if the query contains a BIND clause thous variable is not part of the result variables, but other variables depend on it. Minimal example:
> {code:java}
> import static org.junit.jupiter.api.Assertions.assertTrue;
> import org.apache.jena.query.QueryFactory;
> import org.apache.jena.sparql.algebra.AlgebraGenerator;
> import org.apache.jena.sparql.algebra.OpAsQuery;
> import org.junit.jupiter.api.Test;
> public class OpTest {
> 	@Test
> 	public void retainVariables() {
> 		String sparqlStrBeforOp = "SELECT ?a ?d WHERE { ?a <http://example.org/p> ?b . BIND(?b AS ?c) BIND(?c AS ?d) }";
> 		String sparqlStrAfterOp = OpAsQuery.asQuery(new AlgebraGenerator().compile(QueryFactory.create(sparqlStrBeforOp))).toString();
> 		System.out.println(sparqlStrAfterOp);
> 		assertTrue(sparqlStrAfterOp.contains("(?b AS ?c)"));
> 	}
> }
> {code}
> This results in the following query:
> {code:sql}
> SELECT  ?a (?c AS ?d)
> WHERE
>   { ?a  <http://example.org/p>  ?b }
> {code}
> Use case: I do the conversion back and forth to remove not needed result variables of a given query on algebra level, which is not possible on queries directly.



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