/*
 * Copyright 2006 Amazon Technologies, Inc. or its affiliates.
 * Amazon, Amazon.com and Carbonado are trademarks or registered trademarks
 * of Amazon Technologies, Inc. or its affiliates.  All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.amazon.carbonado;

import java.lang.annotation.*;

/**
 * Identifies a {@link Storable} property as being a member of an alternate
 * key. An alternate key is just as good as the primary key for uniquely
 * identifying a storable instance, except repositories are usually more
 * flexible with alternate keys. For example, dropping an alternate key and
 * reconstructing it should not result in loss of data. Alternate keys are
 * often implemented as indexes with a uniqueness constraint.
 *
 * @author Brian S O'Neill
 * @see AlternateKeys
 */
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({})
public @interface Key {
    /**
     * A list of property names, which may be prefixed with '+' or '-' to
     * indicate a preference for ascending or descending order.
     */
    String[] value();
}