| /* |
| * 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: |
| // James Sutherland - initial implementation |
| package org.eclipse.persistence.annotations; |
| |
| import org.eclipse.persistence.mappings.ForeignReferenceMapping; |
| |
| /** |
| * Enum used with the BatchFetch annotation, or "eclipselink.batch.type" query hint. |
| * This can be specified on a mapping or query to configure the type of batch reading to be used. |
| * |
| * @see BatchFetch |
| * @see ForeignReferenceMapping#setBatchFetchType(BatchFetchType) |
| * @author James Sutherland |
| * @since EclipseLink 2.1 |
| */ |
| public enum BatchFetchType { |
| /** |
| * This is the default form of batch reading. |
| * The original query's selection criteria is joined with the batch query. |
| */ |
| JOIN, |
| |
| /** |
| * This uses an SQL EXISTS and a sub-select in the batch query instead of a join. |
| * This has the advantage of not requiring an SQL DISTINCT which can have issues |
| * with LOBs, or may be more efficient for some types of queries or on some databases. |
| */ |
| EXISTS, |
| |
| /** |
| * This uses an SQL IN clause in the batch query passing in the source object Ids. |
| * This has the advantage of only selecting the objects not already contained in the cache, |
| * and can work better with cursors, or if joins cannot be used. |
| * This may only work for singleton Ids on some databases. |
| */ |
| IN |
| } |