/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2012, Red Hat Inc. or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.loader;

import java.util.Locale;
import org.jboss.logging.Logger;

Defines the style that should be used to perform batch loading. Which style to use is declared using the ""hibernate.batch_fetch_style"" (AvailableSettings.BATCH_FETCH_STYLE) setting
Author:Steve Ebersole
/** * Defines the style that should be used to perform batch loading. Which style to use is declared using * the "{@value org.hibernate.cfg.AvailableSettings#BATCH_FETCH_STYLE}" * ({@link org.hibernate.cfg.AvailableSettings#BATCH_FETCH_STYLE}) setting * * @author Steve Ebersole */
public enum BatchFetchStyle {
The legacy algorithm where we keep a set of pre-built batch sizes based on ArrayHelper.getBatchSizes. Batches are performed using the next-smaller pre-built batch size from the number of existing batchable identifiers.

For example, with a batch-size setting of 32 the pre-built batch sizes would be [32, 16, 10, 9, 8, 7, .., 1]. An attempt to batch load 31 identifiers would result in batches of 16, 10, and 5.
/** * The legacy algorithm where we keep a set of pre-built batch sizes based on * {@link org.hibernate.internal.util.collections.ArrayHelper#getBatchSizes}. Batches are performed * using the next-smaller pre-built batch size from the number of existing batchable identifiers. * <p/> * For example, with a batch-size setting of 32 the pre-built batch sizes would be [32, 16, 10, 9, 8, 7, .., 1]. * An attempt to batch load 31 identifiers would result in batches of 16, 10, and 5. */
LEGACY,
Still keeps the concept of pre-built batch sizes, but uses the next-bigger batch size and pads the extra identifier placeholders.

Using the same example of a batch-size setting of 32 the pre-built batch sizes would be the same. However, the attempt to batch load 31 identifiers would result just a single batch of size 32. The identifiers to load would be "padded" (aka, repeated) to make up the difference.
/** * Still keeps the concept of pre-built batch sizes, but uses the next-bigger batch size and pads the extra * identifier placeholders. * <p/> * Using the same example of a batch-size setting of 32 the pre-built batch sizes would be the same. However, the * attempt to batch load 31 identifiers would result just a single batch of size 32. The identifiers to load would * be "padded" (aka, repeated) to make up the difference. */
PADDED,
Dynamically builds its SQL based on the actual number of available ids. Does still limit to the batch-size defined on the entity/collection
/** * Dynamically builds its SQL based on the actual number of available ids. Does still limit to the batch-size * defined on the entity/collection */
DYNAMIC; private static final Logger log = Logger.getLogger( BatchFetchStyle.class ); public static BatchFetchStyle byName(String name) { return valueOf( name.toUpperCase(Locale.ROOT) ); } public static BatchFetchStyle interpret(Object setting) { log.tracef( "Interpreting BatchFetchStyle from setting : %s", setting ); if ( setting == null ) { return LEGACY; // as default } if ( BatchFetchStyle.class.isInstance( setting ) ) { return (BatchFetchStyle) setting; } try { final BatchFetchStyle byName = byName( setting.toString() ); if ( byName != null ) { return byName; } } catch (Exception ignore) { } log.debugf( "Unable to interpret given setting [%s] as BatchFetchStyle", setting ); return LEGACY; // again as default. } }