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https://issues.apache.org/jira/browse/JENA-2335?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jan Martin Keil updated JENA-2335:
----------------------------------
Description:
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.
was:
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 result variables in
between, which is not possible on queries directly.
> 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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