Account for creation of subRow when field with relationship is not fi…

…rst field and batch size is hit

foundation/org.eclipse.persistence.core/src/main/java/org/eclipse/persistence/queries/ReportQueryResult.java

@@ -252,9 +252,26 @@ protected Object processItem(ReportQuery query, AbstractRecord row, Vector toMan
                 AbstractRecord subRow = row;
                 // Check if at the start of the row, then avoid building a subRow.
                 if (itemIndex > 0) {
-                    Vector<DatabaseField> trimedFields = new NonSynchronizedSubVector<>(row.getFields(), itemIndex, rowSize);
-                    Vector trimedValues = new NonSynchronizedSubVector(row.getValues(), itemIndex, rowSize);
-                    subRow = new DatabaseRecord(trimedFields, trimedValues);
+                    BatchFetchPolicy batchFetchPolicy = query.getBatchFetchPolicy();
+                    if (batchFetchPolicy != null && batchFetchPolicy.isIN()) {
+
+                        List<AbstractRecord> subRows = new ArrayList<>(toManyData.size());
+                        for (AbstractRecord parentRow : (Vector<AbstractRecord>) toManyData) {
+                            Vector<DatabaseField> trimedParentFields = new NonSynchronizedSubVector<>(parentRow.getFields(), itemIndex, rowSize);
+                            Vector trimedParentValues = new NonSynchronizedSubVector<>(parentRow.getValues(), itemIndex, rowSize);
+                            subRows.add(new DatabaseRecord(trimedParentFields, trimedParentValues));
+                        }
+
+                        for (DatabaseMapping subMapping : descriptor.getMappings()) {
+                            batchFetchPolicy.setDataResults(subMapping, subRows);
+                        }
+
+                        subRow = subRows.get(toManyData.indexOf(row));
+                    } else {
+                        Vector<DatabaseField> trimedFields = new NonSynchronizedSubVector<>(row.getFields(), itemIndex, rowSize);
+                        Vector trimedValues = new NonSynchronizedSubVector(row.getValues(), itemIndex, rowSize);
+                        subRow = new DatabaseRecord(trimedFields, trimedValues);
+                    }
                 }
                 if (mapping != null && mapping.isAggregateObjectMapping()){
                     value = ((AggregateObjectMapping)mapping).buildAggregateFromRow(subRow, null, null, joinManager, query, false, query.getSession(), true);

jpa/eclipselink.jpa.testapps/jpa.test.batchfetch/pom.xml

@@ -1,3 +1,17 @@
+<!--
+
+    Copyright (c) 2024 Oracle and/or its affiliates. All rights reserved.
+
+    This program and the accompanying materials are made available under the
+    terms of the Eclipse Public License v. 2.0 which is available at
+    http://www.eclipse.org/legal/epl-2.0,
+    or the Eclipse Distribution License v. 1.0 which is available at
+    http://www.eclipse.org/org/documents/edl-v10.php.
+
+    SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
+
+-->
+
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
     <parent>

jpa/eclipselink.jpa.testapps/jpa.test.batchfetch/src/main/java/org/eclipse/persistence/jpa/testapps/batchfetch/Count.java

@@ -0,0 +1,3 @@
+package org.eclipse.persistence.jpa.testapps.batchfetch;
+
+public record Count(long value, Employee employee) {}

jpa/eclipselink.jpa.testapps/jpa.test.batchfetch/src/test/java/batchfetch/BatchFetchJUnitTest.java

@@ -18,8 +18,10 @@
 import jakarta.persistence.TypedQuery;
 import junit.framework.Test;
 import junit.framework.TestSuite;
+import org.eclipse.persistence.config.QueryHints;
 import org.eclipse.persistence.jpa.testapps.batchfetch.BatchFetchTableCreator;
 import org.eclipse.persistence.jpa.testapps.batchfetch.Company;
+import org.eclipse.persistence.jpa.testapps.batchfetch.Count;
 import org.eclipse.persistence.jpa.testapps.batchfetch.Employee;
 import org.eclipse.persistence.jpa.testapps.batchfetch.Record;
 import org.eclipse.persistence.testing.framework.jpa.junit.JUnitTestCase;
@@ -43,6 +45,7 @@ public static Test suite() {
         suite.addTest(new BatchFetchJUnitTest("testSetup"));
         suite.addTest(new BatchFetchJUnitTest("testSelectRoot"));
         suite.addTest(new BatchFetchJUnitTest("testSelectNonRoot"));
+        suite.addTest(new BatchFetchJUnitTest("testSelectNonRootWithOffsetAndLimit"));
         return suite;
     }
 
@@ -122,6 +125,25 @@ public void testSelectNonRoot() {
         }
     }
 
+    public void testSelectNonRootWithOffsetAndLimit() {
+        EntityManager em = createEntityManager();
+        em.getEntityManagerFactory().getCache().evictAll();
+
+        try {
+            TypedQuery<Count> q = em.createQuery("SELECT new org.eclipse.persistence.jpa.testapps.batchfetch.Count(count(r.employee), r.employee) FROM Record r group by r.employee", Count.class);
+            q.setHint(QueryHints.BATCH_SIZE, 1);
+            List<Count> result = q.getResultList();
+            assertEquals("Not all rows are selected", 3, result.size());
+            List<Employee> employees = result.stream().map(Count::employee).filter(Objects::nonNull).toList();
+            assertEquals("Not all counts have employees", 3, result.size());
+            List<Company> companies = employees.stream().map(Employee::getCompany).filter(Objects::nonNull).toList();
+            assertEquals("Not all employees have companies", 3, companies.size());
+        } catch (RuntimeException e) {
+            closeEntityManager(em);
+            throw e;
+        }
+    }
+
     @Override
     public String getPersistenceUnitName() {
         return "batchfetch";