org.eclipse.persistence.descriptors.partitioning.FieldPartitioningPolicy Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of eclipselink Show documentation
EclipseLink build based upon Git transaction f2b9fc5
There is a newer version: 5.0.0-B03
/*
 * Copyright (c) 2011, 2021 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 (Oracle) - initial API and implementation
package org.eclipse.persistence.descriptors.partitioning;

import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.internal.helper.DatabaseField;
import org.eclipse.persistence.internal.sessions.AbstractSession;
import org.eclipse.persistence.sessions.server.ClientSession;

/**
 * PUBLIC:
 * FieldPartitioningPolicy partitions access to a database cluster by a field value from the object,
 * such as the object's id, location, or tenant.
 * All write or read request for object's with that value are sent to the server.
 * If a query does not include the field as a parameter, then it can either be sent
 * to all server's and unioned, or left to the sesion's default behavior.
 * @author James Sutherland
 * @since EclipseLink 2.2
 */
public abstract class FieldPartitioningPolicy extends PartitioningPolicy {

    /** The column to partition by. */
    protected DatabaseField partitionField;

    /** If query does not have the partition field in it, should the query be sent to all databases. */
    protected boolean unionUnpartitionableQueries = false;

    protected FieldPartitioningPolicy() {
        super();
    }

    protected FieldPartitioningPolicy(String partitionField) {
        super();
        this.partitionField = new DatabaseField(partitionField);
    }

    protected FieldPartitioningPolicy(String partitionField, boolean unionUnpartitionableQueries) {
        this(partitionField);
        this.unionUnpartitionableQueries = unionUnpartitionableQueries;
    }

    /**
     * PUBLIC:
     * Return the database column or query parameter to partition queries by.
     * This is the table column name, not the class attribute name.
     * The column value must be included in the query and should normally be part of the object's Id.
     * This can also be the name of a query parameter.
     * If a query does not contain the field the query will not be partitioned.
     */
    public DatabaseField getPartitionField() {
        return partitionField;
    }

    /**
     * PUBLIC:
     * Set the database column or query parameter to partition queries by.
     * This is the table column name, not the class attribute name.
     * The column value must be included in the query and should normally be part of the object's Id.
     * This can also be the name of a query parameter.
     * If a query does not contain the field the query will not be partitioned.
     */
    public void setPartitionField(DatabaseField partitionField) {
        this.partitionField = partitionField;
    }

    /**
     * PUBLIC:
     * Return the database column or query parameter to partition queries by.
     * This is the table column name, not the class attribute name.
     * The column value must be included in the query and should normally be part of the object's Id.
     * This can also be the name of a query parameter.
     * If a query does not contain the field the query will not be partitioned.
     */
    public String getPartitionFieldName() {
        return getPartitionField().getName();
    }

    /**
     * PUBLIC:
     * Set the database column or query parameter to partition queries by.
     * This is the table column name, not the class attribute name.
     * The column value must be included in the query and should normally be part of the object's Id.
     * This can also be the name of a query parameter.
     * If a query does not contain the field the query will not be partitioned.
     */
    public void setPartitionField(String partitionField) {
        this.partitionField = new DatabaseField(partitionField);
    }

    /**
     * PUBLIC:
     * Return if queries that do not contain the partition field should be sent
     * to every database and have the result unioned.
     */
    public boolean getUnionUnpartitionableQueries() {
        return unionUnpartitionableQueries;
    }

    /**
     * PUBLIC:
     * Set if queries that do not contain the partition field should be sent
     * to every database and have the result unioned.
     */
    public void setUnionUnpartitionableQueries(boolean unionUnpartitionableQueries) {
        this.unionUnpartitionableQueries = unionUnpartitionableQueries;
    }

    /**
     * INTERNAL:
     * If persist should be partitioned, extra value from object.
     */
    protected Object extractPartitionValueForPersist(AbstractSession session, Object object, ClassDescriptor descriptor) {
        if (!session.isClientSession()) {
            return null;
        }
        ClientSession client = (ClientSession)session;
        // Only assign the connection if exclusive.
        if (!client.isExclusiveIsolatedClientSession() || client.hasWriteConnection()) {
            return null;
        }
        return descriptor.getObjectBuilder().extractValueFromObjectForField(object, this.partitionField, session);
    }
}