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https://issues.apache.org/jira/browse/JENA-2335?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17560904#comment-17560904
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Andy Seaborne commented on JENA-2335:
-------------------------------------
Hi [~jmkeil]
This looks like https://github.com/apache/jena/issues/1369
The output from the development code is currently:
{noformat}
SELECT ?a (?c AS ?d)
WHERE
{ ?a <http://example.org/p> ?b
BIND(?b AS ?c)
}
{noformat}
and the invariant of "same algebra" is maintained:
{code:java}
public static void main(String...a) {
String qs = "SELECT ?a ?d WHERE { ?a <http://example.org/p> ?b .
BIND(?b AS ?c) BIND(?c AS ?d) }";
Query q1 = QueryFactory.create(qs);
Op op1 = Algebra.compile(q1);
Query q2 = OpAsQuery.asQuery(op1);
Op op2 = Algebra.compile(q2);
System.out.println(q1);
System.out.println(q2);
System.out.println("Algebra equals: "+op1.equals(op2));
}
{code}
Tests for 1369:
[sparql/algebra/TestOpAsQuery.java|https://github.com/apache/jena/blob/7c0b20742a8fac15da14f256debbbbbeeeb40eaa/jena-arq/src/test/java/org/apache/jena/sparql/algebra/TestOpAsQuery.java#L74]
> 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
> Priority: Major
>
> 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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