allow use of SelectGenerator from annotations

- generalize @GenericGenerator to any Generator
- add tests for @GenericGenerator(type=SelectGenerator)
- move some logic for choosing the right InsertGeneratedIdentifierDelegate
  to the generators themselves

hibernate-core/src/main/java/org/hibernate/annotations/GenericGenerator.java

@@ -6,7 +6,7 @@
  */
 package org.hibernate.annotations;
 
-import org.hibernate.generator.InMemoryGenerator;
+import org.hibernate.generator.Generator;
 
 import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
@@ -19,11 +19,10 @@ import static java.lang.annotation.ElementType.TYPE;
 import static java.lang.annotation.RetentionPolicy.RUNTIME;
 
 /**
- * Defines a named identifier generator, an instance of the interface
+ * Defines a named identifier generator, usually an instance of the interface
- * {@link org.hibernate.id.IdentifierGenerator}. This allows the use of
+ * {@link org.hibernate.id.IdentifierGenerator}. This allows the use of custom
- * custom identifier generation strategies beyond those provided by the
+ * identifier generation strategies beyond those provided by the four basic
- * four basic JPA-defined {@linkplain jakarta.persistence.GenerationType
+ * JPA-defined {@linkplain jakarta.persistence.GenerationType generation types}.
- * generation types}.
  * <p>
  * A named generator may be associated with an entity class by:
  * <ul>
@@ -74,17 +73,17 @@ public @interface GenericGenerator {
 	 */
 	String name();
 	/**
-	 * The type of identifier generator, a class implementing {@link InMemoryGenerator}
+	 * The type of identifier generator, a class implementing {@link Generator}
 	 * or, more commonly, {@link org.hibernate.id.IdentifierGenerator}.
 	 *
 	 * @since 6.2
 	 */
-	Class<? extends InMemoryGenerator> type() default InMemoryGenerator.class;
+	Class<? extends Generator> type() default Generator.class;
 	/**
 	 * The type of identifier generator, the name of either:
 	 * <ul>
 	 * <li>a built-in Hibernate id generator, or
-	 * <li>a custom class implementing {@link InMemoryGenerator}, or, more commonly,
+	 * <li>a custom class implementing {@link Generator}, or, more commonly,
 	 *     {@link org.hibernate.id.IdentifierGenerator}.
 	 * </ul>
 	 *

hibernate-core/src/main/java/org/hibernate/cfg/AnnotationBinder.java

@@ -81,6 +81,7 @@ import org.hibernate.cfg.annotations.QueryBinder;
 import org.hibernate.dialect.TimeZoneSupport;
 import org.hibernate.engine.OptimisticLockStyle;
 import org.hibernate.engine.spi.FilterDefinition;
+import org.hibernate.generator.Generator;
 import org.hibernate.internal.CoreMessageLogger;
 import org.hibernate.internal.util.GenericsHelper;
 import org.hibernate.internal.util.StringHelper;
@@ -98,7 +99,6 @@ import org.hibernate.property.access.internal.PropertyAccessStrategyMixedImpl;
 import org.hibernate.property.access.spi.PropertyAccessStrategy;
 import org.hibernate.resource.beans.spi.ManagedBean;
 import org.hibernate.resource.beans.spi.ManagedBeanRegistry;
-import org.hibernate.generator.InMemoryGenerator;
 import org.hibernate.type.BasicType;
 import org.hibernate.type.CustomType;
 import org.hibernate.type.descriptor.java.BasicJavaType;
@@ -489,7 +489,7 @@ public final class AnnotationBinder {
 		else if ( generatorAnnotation instanceof GenericGenerator ) {
 			final GenericGenerator genericGenerator = (GenericGenerator) generatorAnnotation;
 			definitionBuilder.setName( genericGenerator.name() );
-			final String strategy = genericGenerator.type().equals(InMemoryGenerator.class)
+			final String strategy = genericGenerator.type().equals(Generator.class)
 					? genericGenerator.strategy()
 					: genericGenerator.type().getName();
 			definitionBuilder.setStrategy( strategy );

hibernate-core/src/main/java/org/hibernate/generator/InDatabaseGenerator.java

@@ -7,7 +7,9 @@
 package org.hibernate.generator;
 
 import org.hibernate.dialect.Dialect;
-import org.hibernate.persister.entity.EntityPersister;
+import org.hibernate.id.PostInsertIdentityPersister;
+import org.hibernate.id.insert.BasicSelectingDelegate;
+import org.hibernate.id.insert.InsertGeneratedIdentifierDelegate;
 
 /**
  * A value generated by the database might be generated implicitly, by a trigger, or using
@@ -69,18 +71,15 @@ public interface InDatabaseGenerator extends Generator {
 	String[] getReferencedColumnValues(Dialect dialect);
 
 	/**
-	 * The name of a property of the entity which may be used to locate the just-{@code insert}ed
+	 * The {@link InsertGeneratedIdentifierDelegate} used to retrieve the generates value if this
-	 * row containing the generated value. Of course, the columns mapped by this property should
+	 * object is an identifier generator.
-	 * form a unique key of the entity.
 	 * <p>
 	 * This is ignored by {@link org.hibernate.metamodel.mapping.internal.GeneratedValuesProcessor},
 	 * which handles multiple generators at once. This method arguably breaks the separation of
 	 * concerns between the generator and the coordinating code.
-	 *
-	 * @see org.hibernate.id.SelectGenerator
 	 */
-	default String getUniqueKeyPropertyName(EntityPersister persister) {
+	default InsertGeneratedIdentifierDelegate getGeneratedIdentifierDelegate(PostInsertIdentityPersister persister) {
-		return null;
+		return new BasicSelectingDelegate( persister, persister.getFactory().getJdbcServices().getDialect() );
 	}
 
 	default boolean generatedByDatabase() {

hibernate-core/src/main/java/org/hibernate/id/IdentityGenerator.java

@@ -9,6 +9,9 @@ package org.hibernate.id;
 import org.hibernate.dialect.Dialect;
 import org.hibernate.id.factory.spi.StandardGenerator;
 import org.hibernate.generator.InDatabaseGenerator;
+import org.hibernate.id.insert.BasicSelectingDelegate;
+import org.hibernate.id.insert.InsertGeneratedIdentifierDelegate;
+import org.hibernate.id.insert.InsertReturningDelegate;
 
 /**
  * An {@link InDatabaseGenerator} that handles {@code IDENTITY}/"autoincrement" columns
@@ -16,11 +19,23 @@ import org.hibernate.generator.InDatabaseGenerator;
  * <p>
  * Delegates to the {@link org.hibernate.dialect.identity.IdentityColumnSupport} provided
  * by the {@linkplain Dialect#getIdentityColumnSupport() dialect}.
+ * <p>
+ * The actual work involved in retrieving the primary key value is the job of a
+ * {@link org.hibernate.id.insert.InsertGeneratedIdentifierDelegate}, either:
+ * <ul>
+ * <li>a {@link org.hibernate.id.insert.GetGeneratedKeysDelegate},
+ * <li>an {@link org.hibernate.id.insert.InsertReturningDelegate}, or a
+ * <li>a {@link org.hibernate.id.insert.BasicSelectingDelegate}.
+ * </ul>
+ *
+ * @see org.hibernate.dialect.identity.IdentityColumnSupport
+ * @see org.hibernate.id.insert.InsertGeneratedIdentifierDelegate
  *
  * @author Christoph Sturm
  */
 public class IdentityGenerator
 		implements PostInsertIdentifierGenerator, BulkInsertionCapableIdentifierGenerator, StandardGenerator {
+
 	@Override
 	public boolean referenceColumnsInSql(Dialect dialect) {
 		return dialect.getIdentityColumnSupport().hasIdentityInsertKeyword();
@@ -30,4 +45,18 @@ public class IdentityGenerator
 	public String[] getReferencedColumnValues(Dialect dialect) {
 		return new String[] { dialect.getIdentityColumnSupport().getIdentityInsertString() };
 	}
+
+	@Override
+	public InsertGeneratedIdentifierDelegate getGeneratedIdentifierDelegate(PostInsertIdentityPersister persister) {
+		Dialect dialect = persister.getFactory().getJdbcServices().getDialect();
+		if ( persister.getFactory().getSessionFactoryOptions().isGetGeneratedKeysEnabled() ) {
+			return dialect.getIdentityColumnSupport().buildGetGeneratedKeysDelegate( persister, dialect );
+		}
+		else if ( dialect.getIdentityColumnSupport().supportsInsertSelectIdentity() ) {
+			return new InsertReturningDelegate( persister, dialect );
+		}
+		else {
+			return new BasicSelectingDelegate( persister, dialect );
+		}
+	}
 }

hibernate-core/src/main/java/org/hibernate/id/PostInsertIdentifierGenerator.java

@@ -18,7 +18,7 @@ import java.util.Properties;
 import static org.hibernate.generator.EventTypeSets.INSERT_ONLY;
 
 /**
- * The counterpart of {@link IdentifierGenerator} for values generated by the database.
+ * The counterpart to {@link IdentifierGenerator} for values generated by the database.
  * This interface is no longer the only way to handle database-generate identifiers.
  * Any {@link InDatabaseGenerator} with timing {@link EventTypeSets#INSERT_ONLY} may now
  * be used.

hibernate-core/src/main/java/org/hibernate/id/SelectGenerator.java

@@ -11,14 +11,16 @@ import java.util.Properties;
 import org.hibernate.dialect.Dialect;
 import org.hibernate.generator.InDatabaseGenerator;
 import org.hibernate.id.factory.spi.StandardGenerator;
+import org.hibernate.id.insert.InsertGeneratedIdentifierDelegate;
+import org.hibernate.id.insert.UniqueKeySelectingDelegate;
 import org.hibernate.persister.entity.EntityPersister;
 import org.hibernate.service.ServiceRegistry;
 import org.hibernate.type.Type;
 
 /**
  * A generator that {@code select}s the just-{@code insert}ed row to determine the
- * column value assigned by the database. The correct row is located
+ * column value assigned by the database. The correct row is located using a unique
- * using a unique key of the entity, either:
+ * key of the entity, either:
  * <ul>
  * <li>the mapped {@linkplain org.hibernate.annotations.NaturalId} of the entity, or
  * <li>a property specified using the parameter named {@code "key"}.
@@ -26,11 +28,32 @@ import org.hibernate.type.Type;
  * The second approach is provided for backward compatibility with older versions of
  * Hibernate.
  * <p>
+ * This generator is intended for use with primary keys assigned by a database trigger
+ * or something similar, for example:
+ * <pre>{@code
+ * @Entity @Table(name="TableWithPKAssignedByTrigger")
+ * @GenericGenerator(name = "triggered", type = SelectGenerator.class)
+ * public class TriggeredEntity {
+ *     @Id @GeneratedValue(generator = "triggered")
+ *     private Long id;
+ *
+ *     @NaturalId
+ *     private String name;
+ *
+ *     ...
+ * }
+ * }</pre>
+ * For tables with identity/autoincrement columns, use {@link IdentityGenerator}.
+ * <p>
+ * The actual work involved in retrieving the primary key value is the job of
+ * {@link org.hibernate.id.insert.UniqueKeySelectingDelegate}.
+ * <p>
  * Arguably, this class breaks the natural separation of responsibility between the
- * {@linkplain InDatabaseGenerator generator} and the coordinating
+ * {@linkplain InDatabaseGenerator generator} and the coordinating code, since its
- * code, since it's role is to specify how the generated value is <em>retrieved</em>.
+ * role is to specify how the generated value is <em>retrieved</em>.
  *
  * @see org.hibernate.annotations.NaturalId
+ * @see org.hibernate.id.insert.UniqueKeySelectingDelegate
  *
  * @author Gavin King
  */
@@ -43,8 +66,12 @@ public class SelectGenerator
 		uniqueKeyPropertyName = parameters.getProperty( "key" );
 	}
 
-	@Override
+	/**
-	public String getUniqueKeyPropertyName(EntityPersister persister) {
+	 * The name of a property of the entity which may be used to locate the just-{@code insert}ed
+	 * row containing the generated value. Of course, the columns mapped by this property should
+	 * form a unique key of the entity.
+	 */
+	protected String getUniqueKeyPropertyName(EntityPersister persister) {
 		if ( uniqueKeyPropertyName != null ) {
 			return uniqueKeyPropertyName;
 		}
@@ -70,6 +97,12 @@ public class SelectGenerator
 		return persister.getPropertyNames()[naturalIdPropertyIndices[0]];
 	}
 
+	@Override
+	public InsertGeneratedIdentifierDelegate getGeneratedIdentifierDelegate(PostInsertIdentityPersister persister) {
+		Dialect dialect = persister.getFactory().getJdbcServices().getDialect();
+		return new UniqueKeySelectingDelegate( persister, dialect, getUniqueKeyPropertyName( persister ) );
+	}
+
 	@Override
 	public boolean referenceColumnsInSql(Dialect dialect) {
 		return false;

hibernate-core/src/main/java/org/hibernate/id/insert/InsertGeneratedIdentifierDelegate.java

@@ -13,14 +13,13 @@ import org.hibernate.engine.jdbc.mutation.JdbcValueBindings;
 import org.hibernate.engine.jdbc.mutation.group.PreparedStatementDetails;
 import org.hibernate.engine.spi.SessionFactoryImplementor;
 import org.hibernate.engine.spi.SharedSessionContractImplementor;
-import org.hibernate.generator.InDatabaseGenerator;
 import org.hibernate.jdbc.Expectation;
 import org.hibernate.metamodel.mapping.BasicEntityIdentifierMapping;
 import org.hibernate.sql.model.ast.builder.TableInsertBuilder;
 
 /**
  * Each implementation defines a strategy for retrieving a primary key
- * {@linkplain InDatabaseGenerator generated by
+ * {@linkplain org.hibernate.generator.InDatabaseGenerator generated by
  * the database} from the database after execution of an {@code insert}
  * statement. The generated primary key is usually an {@code IDENTITY}
  * column, but in principle it might be something else, for example,
@@ -32,9 +31,9 @@ import org.hibernate.sql.model.ast.builder.TableInsertBuilder;
  * <li>retrieving the generated identifier value using JDBC.
  * </ul>
  * The implementation should be written to handle any instance of
- * {@link InDatabaseGenerator}.
+ * {@link org.hibernate.generator.InDatabaseGenerator}.
  *
- * @see InDatabaseGenerator
+ * @see org.hibernate.generator.InDatabaseGenerator
  *
  * @author Steve Ebersole
  */

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

@@ -2743,29 +2743,6 @@ public abstract class AbstractEntityPersister
 		return includeProperty[getVersionProperty()] || entityMetamodel.isVersionGeneratedByDatabase();
 	}
 
-	public boolean useGetGeneratedKeys() {
-		return getFactory().getSessionFactoryOptions().isGetGeneratedKeysEnabled();
-	}
-
-	public InsertGeneratedIdentifierDelegate getGeneratedIdentifierDelegate() {
-		Dialect dialect = getFactory().getJdbcServices().getDialect();
-		if ( useGetGeneratedKeys() ) {
-			return dialect.getIdentityColumnSupport().buildGetGeneratedKeysDelegate(this, dialect );
-		}
-		else if ( dialect.getIdentityColumnSupport().supportsInsertSelectIdentity() ) {
-			return new InsertReturningDelegate(this, dialect );
-		}
-		else {
-			return new BasicSelectingDelegate(this, dialect );
-		}
-	}
-
-	@Override
-	public InsertGeneratedIdentifierDelegate getGeneratedIdentifierDelegateForProperty(String uniqueKeyPropertyName) {
-		Dialect dialect = getFactory().getJdbcServices().getDialect();
-		return new UniqueKeySelectingDelegate( this, dialect, uniqueKeyPropertyName );
-	}
-
 	@Override
 	public String getIdentitySelectString() {
 		//TODO: cache this in an instvar
@@ -3082,10 +3059,7 @@ public abstract class AbstractEntityPersister
 	private void doLateInit() {
 		if ( isIdentifierAssignedByInsert() ) {
 			final InDatabaseGenerator generator = (InDatabaseGenerator) getGenerator();
-			final String uniqueKeyPropertyName = generator.getUniqueKeyPropertyName(this);
+			identityDelegate = generator.getGeneratedIdentifierDelegate( this );
-			identityDelegate = uniqueKeyPropertyName == null
-					? getGeneratedIdentifierDelegate()
-					: getGeneratedIdentifierDelegateForProperty( uniqueKeyPropertyName );
 		}
 
 		tableMappings = buildTableMappings();

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

@@ -1015,14 +1015,6 @@ public interface EntityPersister extends EntityMappingType, RootTableGroupProduc
 
 	boolean canUseReferenceCacheEntries();
 
-	default InsertGeneratedIdentifierDelegate getGeneratedIdentifierDelegate() {
-		return null;
-	}
-
-	default InsertGeneratedIdentifierDelegate getGeneratedIdentifierDelegateForProperty(String uniqueKeyPropertyName) {
-		return null;
-	}
-
 	/**
 	 * The property name of the "special" identifier property in HQL
 	 *

hibernate-core/src/main/java/org/hibernate/query/sqm/mutation/internal/temptable/InsertExecutionDelegate.java

@@ -25,6 +25,7 @@ import org.hibernate.engine.spi.SharedSessionContractImplementor;
 import org.hibernate.generator.EventType;
 import org.hibernate.id.BulkInsertionCapableIdentifierGenerator;
 import org.hibernate.id.OptimizableGenerator;
+import org.hibernate.id.PostInsertIdentityPersister;
 import org.hibernate.id.enhanced.Optimizer;
 import org.hibernate.id.insert.Binder;
 import org.hibernate.id.insert.InsertGeneratedIdentifierDelegate;
@@ -559,10 +560,8 @@ public class InsertExecutionDelegate implements TableBasedInsertHandler.Executio
 
 		if ( generator.generatedByDatabase() ) {
 			final InDatabaseGenerator databaseGenerator = (InDatabaseGenerator) generator;
-			final String uniqueKeyPropertyName = databaseGenerator.getUniqueKeyPropertyName( entityPersister );
+			final InsertGeneratedIdentifierDelegate identifierDelegate =
-			final InsertGeneratedIdentifierDelegate identifierDelegate = uniqueKeyPropertyName == null
+					databaseGenerator.getGeneratedIdentifierDelegate( (PostInsertIdentityPersister) entityPersister );
-					? entityPersister.getGeneratedIdentifierDelegate()
-					: entityPersister.getGeneratedIdentifierDelegateForProperty( uniqueKeyPropertyName );
 			final String finalSql = identifierDelegate.prepareIdentifierGeneratingInsert( jdbcInsert.getSqlString() );
 			final BasicEntityIdentifierMapping identifierMapping = (BasicEntityIdentifierMapping) entityDescriptor.getIdentifierMapping();
 			final ValueBinder jdbcValueBinder = identifierMapping.getJdbcMapping().getJdbcValueBinder();

hibernate-core/src/test/java/org/hibernate/orm/test/generatedkeys/selectannotated/MyEntity.hbm.xml

@@ -0,0 +1,31 @@
+<?xml version="1.0"?>
+<!--
+  ~ 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>.
+  -->
+<!DOCTYPE hibernate-mapping PUBLIC
+	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
+	"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
+
+<hibernate-mapping package="org.hibernate.orm.test.generatedkeys.select" default-access="field">
+
+    <database-object>
+        <create>
+            <![CDATA[CREATE OR REPLACE TRIGGER t_i_my_entity
+            BEFORE INSERT ON my_entity
+            FOR EACH ROW
+            BEGIN
+                select nvl( max(id), 0 ) + 1
+                into :new.id
+                from my_entity;
+            END;]]>
+        </create>
+        <drop>
+            <![CDATA[DROP TRIGGER t_i_my_entity]]>
+        </drop>
+        <dialect-scope name="org.hibernate.dialect.OracleDialect"/>
+    </database-object>
+
+</hibernate-mapping>

hibernate-core/src/test/java/org/hibernate/orm/test/generatedkeys/selectannotated/MyEntity.java

@@ -0,0 +1,48 @@
+/*
+ * 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.generatedkeys.selectannotated;
+
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.Id;
+import jakarta.persistence.Table;
+import org.hibernate.annotations.GenericGenerator;
+import org.hibernate.annotations.NaturalId;
+import org.hibernate.id.SelectGenerator;
+
+/**
+ * @author <a href="mailto:steve@hibernate.org">Steve Ebersole </a>
+ */
+@Entity @Table(name="my_entity")
+@GenericGenerator(name = "triggered", type = SelectGenerator.class)
+public class MyEntity {
+	@Id @GeneratedValue(generator = "triggered")
+	private Long id;
+
+	@NaturalId
+	private String name;
+
+	public MyEntity() {
+	}
+
+	public MyEntity(String name) {
+		this.name = name;
+	}
+
+	public Long getId() {
+		return id;
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+}

hibernate-core/src/test/java/org/hibernate/orm/test/generatedkeys/selectannotated/SelectGeneratorTest.java

@@ -0,0 +1,71 @@
+/*
+ * 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.generatedkeys.selectannotated;
+
+import org.hibernate.dialect.OracleDialect;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.JiraKey;
+import org.hibernate.testing.orm.junit.RequiresDialect;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.hibernate.tool.hbm2ddl.SchemaExport;
+import org.hibernate.tool.schema.TargetType;
+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.util.EnumSet;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+
+/**
+ * @author Steve Ebersole
+ * @author Marco Belladelli
+ */
+@DomainModel(
+		annotatedClasses = MyEntity.class,
+		xmlMappings = "org/hibernate/orm/test/generatedkeys/selectannotated/MyEntity.hbm.xml"
+)
+@SessionFactory
+@RequiresDialect(value = OracleDialect.class)
+public class SelectGeneratorTest {
+
+	@Test
+	public void testJDBC3GetGeneratedKeysSupportOnOracle(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					MyEntity e = new MyEntity( "entity-1" );
+					session.persist( e );
+
+					// this insert should happen immediately!
+					assertEquals( Long.valueOf( 1L ), e.getId(), "id not generated through forced insertion" );
+
+					session.remove( e );
+				}
+		);
+	}
+
+	@Test
+	@JiraKey("HHH-15900")
+	public void testGeneratedKeyNotIdentityColumn(SessionFactoryScope scope) throws IOException {
+		File output = File.createTempFile( "schema_export", ".sql" );
+		output.deleteOnExit();
+
+		final SchemaExport schemaExport = new SchemaExport();
+		schemaExport.setOutputFile( output.getAbsolutePath() );
+		schemaExport.execute(
+				EnumSet.of( TargetType.SCRIPT ),
+				SchemaExport.Action.CREATE,
+				scope.getMetadataImplementor()
+		);
+
+		String fileContent = new String( Files.readAllBytes( output.toPath() ) );
+		assertFalse( fileContent.toLowerCase().contains( "identity" ), "Column was generated as identity" );
+	}
+}