/******************************************************************************* | |
* Copyright (c) 2011, 2013 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 v1.0 and Eclipse Distribution License v. 1.0 | |
* which accompanies this distribution. | |
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html | |
* and the Eclipse Distribution License is available at | |
* http://www.eclipse.org/org/documents/edl-v10.php. | |
* | |
* 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#setBatchFetch(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 | |
} |