From e5f28ae17afbb69ae38fc96b7bbc31e676fb099d Mon Sep 17 00:00:00 2001
From: Christian Beikov <christian.beikov@gmail.com>
Date: Mon, 11 Apr 2022 13:21:44 +0200
Subject: [PATCH] HHH-15202 Only create SubselectFetch if entity contains
 subselect fetch config

---
 .../hibernate/engine/spi/SubselectFetch.java  |   3 +
 .../test/batchfetch/SubselectFetchTest.java   | 128 ++++++++++++++++++
 2 files changed, 131 insertions(+)
 create mode 100644 hibernate-core/src/test/java/org/hibernate/orm/test/batchfetch/SubselectFetchTest.java

diff --git a/hibernate-core/src/main/java/org/hibernate/engine/spi/SubselectFetch.java b/hibernate-core/src/main/java/org/hibernate/engine/spi/SubselectFetch.java
index 959e3e9e02..8c62bf4436 100644
--- a/hibernate-core/src/main/java/org/hibernate/engine/spi/SubselectFetch.java
+++ b/hibernate-core/src/main/java/org/hibernate/engine/spi/SubselectFetch.java
@@ -157,6 +157,9 @@ public class SubselectFetch {
 		}
 
 		public void addKey(EntityKey key, LoadingEntityEntry entry) {
+			if ( !entry.getDescriptor().hasSubselectLoadableCollections() ) {
+				return;
+			}
 			final SubselectFetch subselectFetch = subselectFetches.computeIfAbsent(
 					entry.getEntityInitializer().getNavigablePath(),
 					navigablePath -> new SubselectFetch(
diff --git a/hibernate-core/src/test/java/org/hibernate/orm/test/batchfetch/SubselectFetchTest.java b/hibernate-core/src/test/java/org/hibernate/orm/test/batchfetch/SubselectFetchTest.java
new file mode 100644
index 0000000000..18e31f21a4
--- /dev/null
+++ b/hibernate-core/src/test/java/org/hibernate/orm/test/batchfetch/SubselectFetchTest.java
@@ -0,0 +1,128 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.orm.test.batchfetch;
+
+import java.util.List;
+
+import org.hibernate.engine.spi.BatchFetchQueue;
+import org.hibernate.persister.entity.EntityPersister;
+
+import org.hibernate.testing.TestForIssue;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.Id;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.OneToOne;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@DomainModel(
+		annotatedClasses = {
+				SubselectFetchTest.Employee.class,
+				SubselectFetchTest.Task.class
+		}
+)
+@SessionFactory
+public class SubselectFetchTest {
+	private static final int NUMBER_OF_EMPLOYEES = 8;
+
+	@BeforeEach
+	public void createData(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					for ( int i = 0; i < NUMBER_OF_EMPLOYEES; i++ ) {
+						Task mainTask = new Task();
+						mainTask.id = 100 + i;
+						session.persist( mainTask );
+						Task task = new Task();
+						task.id = i;
+						task.parentTask = mainTask;
+						session.persist( task );
+						Employee e = new Employee( "employee0" + i );
+						e.task = task;
+						session.persist( e );
+					}
+				}
+		);
+	}
+
+	@AfterEach
+	public void deleteData(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					session.createQuery( "delete from Employee" ).executeUpdate();
+					session.createQuery( "delete from Task where parentTask is not null" ).executeUpdate();
+					session.createQuery( "delete from Task" ).executeUpdate();
+				}
+		);
+	}
+
+	@Test
+	@TestForIssue( jiraKey = "HHH-15202")
+	public void testSubselectFetchOnlyCreatedIfEnabled(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					EntityPersister employeePersister = session.getSessionFactory()
+							.getRuntimeMetamodels()
+							.getMappingMetamodel()
+							.getEntityDescriptor( Employee.class );
+					EntityPersister taskPersister = session.getSessionFactory()
+							.getRuntimeMetamodels()
+							.getMappingMetamodel()
+							.getEntityDescriptor( Task.class );
+					BatchFetchQueue batchFetchQueue = session.getPersistenceContextInternal().getBatchFetchQueue();
+					List<Employee> results = session.createQuery( "from Employee e order by e.id", Employee.class ).getResultList();
+					for ( Employee result : results ) {
+						assertThat( batchFetchQueue.getSubselect( session.generateEntityKey( result.name, employeePersister ) ) ).isNull();
+						Task task = session.createQuery( "from Task t where t.employee = :e", Task.class )
+								.setParameter( "e", result )
+								.getSingleResult();
+						assertThat( batchFetchQueue.getSubselect( session.generateEntityKey( task.id, taskPersister ) ) ).isNull();
+					}
+				}
+		);
+	}
+
+	@Entity(name = "Employee")
+	public static class Employee {
+		@Id
+		private String name;
+
+		@OneToOne(fetch = FetchType.LAZY)
+		private Task task;
+
+		private Employee() {
+		}
+
+		private Employee(String name) {
+			this.name = name;
+		}
+	}
+
+	@Entity(name = "Task")
+	public static class Task {
+		@Id
+		private long id;
+
+		@ManyToOne(fetch = FetchType.LAZY)
+		private Task parentTask;
+
+		@OneToOne(fetch = FetchType.LAZY, mappedBy = "task")
+		private Employee employee;
+
+		public Task() {
+		}
+	}
+
+}