[6.6] HHH-19457 Inheritance with type JOINED not working in a related entity

hibernate-core/src/main/java/org/hibernate/persister/entity/JoinedSubclassEntityPersister.java

@@ -1437,15 +1437,16 @@ private boolean applyDiscriminatorPredicate(
 			Map<String, EntityNameUse> entityNameUses,
 			MappingMetamodelImplementor metamodel) {
 		if ( tableReference.getTableExpression().equals( getRootTableName() ) ) {
-			assert join.getJoinType() == SqlAstJoinType.INNER : "Found table reference join with root table of non-INNER type: " + join.getJoinType();
 			final String discriminatorPredicate = getPrunedDiscriminatorPredicate(
 					entityNameUses,
 					metamodel,
 					"t"
-//					tableReference.getIdentificationVariable()
 			);
-			tableReference.setPrunedTableExpression( "(select * from " + getRootTableName() + " t where " + discriminatorPredicate + ")" );
-//			join.applyPredicate( new SqlFragmentPredicate( discriminatorPredicate ) );
+			// null means we're filtering for all subtypes, so we don't need to apply a predicate
+			if ( discriminatorPredicate != null ) {
+				assert join.getJoinType() == SqlAstJoinType.INNER : "Found table reference join with root table of non-INNER type: " + join.getJoinType();
+				tableReference.setPrunedTableExpression( "(select * from " + getRootTableName() + " t where " + discriminatorPredicate + ")" );
+			}
 			return true;
 		}
 		return false;

hibernate-core/src/test/java/org/hibernate/orm/test/mapping/inheritance/joined/JoinedDiscriminatorSameChildTableTest.java

@@ -0,0 +1,163 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.orm.test.mapping.inheritance.joined;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.DiscriminatorColumn;
+import jakarta.persistence.DiscriminatorValue;
+import jakarta.persistence.Entity;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.Id;
+import jakarta.persistence.Inheritance;
+import jakarta.persistence.InheritanceType;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.OneToMany;
+import jakarta.persistence.Table;
+import org.hibernate.testing.jdbc.SQLStatementInspector;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.Jira;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@DomainModel(annotatedClasses = {
+		JoinedDiscriminatorSameChildTableTest.EntityParent.class,
+		JoinedDiscriminatorSameChildTableTest.EntityChildOne.class,
+		JoinedDiscriminatorSameChildTableTest.EntityChildTwo.class,
+		JoinedDiscriminatorSameChildTableTest.EntityRelation.class,
+})
+@SessionFactory(useCollectingStatementInspector = true)
+@Jira("https://hibernate.atlassian.net/browse/HHH-19457")
+public class JoinedDiscriminatorSameChildTableTest {
+	@Test
+	public void testParents(SessionFactoryScope scope) {
+		final SQLStatementInspector inspector = scope.getCollectingStatementInspector();
+
+		scope.inSession( session -> {
+			final EntityRelation relation = session.find( EntityRelation.class, "relation_1" );
+			inspector.clear();
+			assertThat( relation.getParents() ).hasSize( 2 );
+		} );
+		// no need to filter by discriminator column, as we're selecting all subtypes of EntityParent
+		inspector.assertNumberOfOccurrenceInQueryNoSpace( 0, "disc_col", 1 );
+
+		scope.inSession( session -> {
+			final EntityRelation relation = session.createQuery(
+					"from EntityRelation where id = 'relation_1'",
+					EntityRelation.class
+			).getSingleResult();
+			inspector.clear();
+			assertThat( relation.getParents() ).hasSize( 2 );
+		} );
+		inspector.assertNumberOfOccurrenceInQueryNoSpace( 0, "disc_col", 1 );
+	}
+
+	@BeforeAll
+	public void setUp(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final EntityRelation relation = new EntityRelation();
+			relation.setId( "relation_1" );
+			session.persist( relation );
+
+			final EntityChildOne c1 = new EntityChildOne();
+			c1.setId( "child_1" );
+			c1.setIdRelation( "relation_1" );
+			session.persist( c1 );
+
+			final EntityChildTwo c2 = new EntityChildTwo();
+			c2.setId( "child_2" );
+			c2.setIdRelation( "relation_1" );
+			session.persist( c2 );
+		} );
+	}
+
+	@AfterAll
+	public void tearDown(SessionFactoryScope scope) {
+		scope.getSessionFactory().getSchemaManager().truncateMappedObjects();
+	}
+
+	@Entity(name = "EntityParent")
+	@Table(name = "parent_table")
+	@Inheritance(strategy = InheritanceType.JOINED)
+	@DiscriminatorColumn(name = "disc_col")
+	static abstract class EntityParent {
+		@Id
+		@Column(name = "id")
+		private String id;
+
+		@Column(name = "id_relation")
+		private String idRelation;
+
+		@ManyToOne(fetch = FetchType.LAZY)
+		@JoinColumn(name = "id_relation", referencedColumnName = "id", insertable = false, updatable = false)
+		private EntityRelation relation;
+
+		public EntityRelation getRelation() {
+			return relation;
+		}
+
+		public void setRelation(EntityRelation requisition) {
+			this.relation = requisition;
+		}
+
+		public String getIdRelation() {
+			return idRelation;
+		}
+
+		public void setIdRelation(String idRelation) {
+			this.idRelation = idRelation;
+		}
+
+		public String getId() {
+			return id;
+		}
+
+		public void setId(String id) {
+			this.id = id;
+		}
+	}
+
+	@Entity(name = "EntityRelation")
+	static class EntityRelation {
+		@Id
+		private String id;
+
+		@OneToMany(fetch = FetchType.LAZY, mappedBy = "relation")
+		private List<EntityParent> parents;
+
+		public void setId(String id) {
+			this.id = id;
+		}
+
+		public String getId() {
+			return id;
+		}
+
+		public List<EntityParent> getParents() {
+			return parents;
+		}
+	}
+
+	@Entity(name = "EntityChildOne")
+	@Table(name = "child_table")
+	@DiscriminatorValue("child-one")
+	static class EntityChildOne extends EntityParent {
+		private String name;
+	}
+
+	@Entity(name = "EntityChildTwo")
+	@Table(name = "child_table")
+	@DiscriminatorValue("child-two")
+	static class EntityChildTwo extends EntityParent {
+		private Integer age;
+	}
+}