HHH-8535 Generating an ID with TableGenerator causes a loop if next_val is NULL

hibernate-core/src/main/java/org/hibernate/id/enhanced/TableGenerator.java

@@ -14,6 +14,7 @@
 import java.util.Properties;
 import java.util.function.BiConsumer;
 
+import org.hibernate.HibernateException;
 import org.hibernate.LockMode;
 import org.hibernate.LockOptions;
 import org.hibernate.MappingException;
@@ -584,6 +585,11 @@ private IntegralDataTypeHolder nextValue(
 				else {
 					final int defaultValue = storeLastUsedValue ? 0 : 1;
 					value.initialize( selectRS, defaultValue );
+					if ( selectRS.wasNull() ) {
+						throw new HibernateException(
+								String.format( "%s for %s '%s' is null", valueColumnName, segmentColumnName,
+										segmentValue ) );
+					}
 				}
 				selectRS.close();
 			}

hibernate-core/src/test/java/org/hibernate/orm/test/schemaupdate/idgenerator/TableGeneratorNextValNullTest.java

@@ -0,0 +1,63 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.orm.test.schemaupdate.idgenerator;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+
+import jakarta.persistence.TableGenerator;
+import org.hibernate.HibernateException;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.JiraKey;
+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.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+@JiraKey(value = "HHH-8535")
+@DomainModel(annotatedClasses = {TableGeneratorNextValNullTest.Author.class})
+@SessionFactory
+public class TableGeneratorNextValNullTest {
+
+	@AfterAll
+	public void dropTestData(SessionFactoryScope scope) {
+		scope.dropData();
+	}
+
+	@Test
+	void hhh8535Test(SessionFactoryScope scope) {
+
+		// This situation can only happen via human being or bad migration/clone script.
+		// Simulate this record being updated post table generation.
+		scope.inTransaction( session -> {
+			session.createNativeMutationQuery(
+					"UPDATE generator SET next_val = null where sequence_name = 'Author'"
+			).executeUpdate();
+		} );
+
+		HibernateException hibernateException = assertThrows( HibernateException.class,
+				() -> scope.inTransaction( session -> {
+					Author author = new Author();
+					session.persist( author );
+				} ) );
+
+		assertEquals( "next_val for sequence_name 'Author' is null", hibernateException.getMessage() );
+	}
+
+	@Entity(name = "Author")
+	public static class Author {
+
+		@Id
+		@GeneratedValue(strategy = GenerationType.TABLE, generator = "generator")
+		@TableGenerator(name = "generator", table = "generator")
+		long id;
+	}
+
+}