| /* |
| * Copyright (c) 2011, 2020 Oracle and/or its affiliates. All rights reserved. |
| * |
| * This program and the accompanying materials are made available under the |
| * terms of the Eclipse Public License v. 2.0 which is available at |
| * http://www.eclipse.org/legal/epl-2.0, |
| * or the Eclipse Distribution License v. 1.0 which is available at |
| * http://www.eclipse.org/org/documents/edl-v10.php. |
| * |
| * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause |
| */ |
| |
| // Contributors: |
| // 01/19/2010-2.1 Guy Pelletier |
| // - 211322: Add fetch-group(s) support to the EclipseLink-ORM.XML Schema |
| // 06/12/2017-2.7 Lukas Jungmann |
| // - 518155: [jpa22] add support for repeatable annotations |
| package org.eclipse.persistence.annotations; |
| |
| import java.lang.annotation.Retention; |
| import java.lang.annotation.Target; |
| |
| import static java.lang.annotation.ElementType.TYPE; |
| import static java.lang.annotation.RetentionPolicy.RUNTIME; |
| |
| import java.lang.annotation.Repeatable; |
| |
| /** |
| * A fetch group is a performance enhancement that allows a group of attributes |
| * of an object to be loaded on demand, which means that the data for an |
| * attribute might not loaded from the underlying data source until an explicit |
| * access call for the attribute first occurs. It avoids the wasteful practice |
| * of loading up all data of the object's attributes, in which the user is |
| * interested in only partial of them. |
| * |
| * A great deal of caution and careful system use case analysis should be use |
| * when using the fetch group feature, as the extra round-trip would well offset |
| * the gain from the deferred loading in many cases. |
| * |
| * EclipseLink fetch group support is twofold: the pre-defined fetch groups at |
| * the Entity or MappedSuperclass level; and dynamic (use case) fetch groups at |
| * the query level. |
| * |
| * Fetch groups can only be used when weaving is enabled or when individual |
| * classes that define them explicitly implement the |
| * org.eclipse.persistence.queries.FetchGroupTracker interface. |
| * |
| * @author Guy Pelletier |
| * @since EclipseLink 2.1 |
| */ |
| @Target({TYPE}) |
| @Retention(RUNTIME) |
| @Repeatable(FetchGroups.class) |
| public @interface FetchGroup { |
| /** |
| * (Required) The fetch group name. |
| */ |
| String name(); |
| |
| /** |
| * (Optional) Indicates whether all relationship attributes |
| * specified in the fetch group should be loaded. |
| */ |
| boolean load() default false; |
| |
| /** |
| * (Required) The list of attributes to fetch. |
| */ |
| FetchAttribute[] attributes(); |
| } |