https://github.com/javaee/jpa-spec: Java(TM) Persistence API 
Copyright (c) 2011 - 2013 Oracle Corporation. 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:
    Linda DeMichiel - Java Persistence 2.1

/*******************************************************************************
 * Copyright (c) 2011 - 2013 Oracle Corporation. 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:
 *     Linda DeMichiel - Java Persistence 2.1
 *
 ******************************************************************************/
package javax.persistence;

import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;


Used in schema generation to specify creation of an index.


Note that it is not necessary to specify an index for a primary key,
as the primary key index will be created automatically.

 
The syntax of the columnList element is a 
column_list, as follows:

   column::= index_column [,index_column]*
   index_column::= column_name [ASC | DESC]



 If ASC or DESC is not specified, 
ASC (ascending order) is assumed.

See Also:
Since:Java Persistence 2.1
/**
 * Used in schema generation to specify creation of an index.
 * <p>
 * Note that it is not necessary to specify an index for a primary key,
 * as the primary key index will be created automatically.
 *
 * <p> 
 * The syntax of the <code>columnList</code> element is a 
 * <code>column_list</code>, as follows:
 * 
 * <pre>
 *    column::= index_column [,index_column]*
 *    index_column::= column_name [ASC | DESC]
 * </pre>
 * 
 * <p> If <code>ASC</code> or <code>DESC</code> is not specified, 
 * <code>ASC</code> (ascending order) is assumed.
 *
 * @see Table
 * @see SecondaryTable
 * @see CollectionTable
 * @see JoinTable
 * @see TableGenerator
 *
 * @since Java Persistence 2.1
 *
 */
@Target({})
@Retention(RUNTIME)
public @interface Index {

    
(Optional) The name of the index; defaults to a provider-generated name.

/**
     * (Optional) The name of the index; defaults to a provider-generated name.
     */
    String name() default "";

    
(Required) The names of the columns to be included in the index, 
in order.

/**
     * (Required) The names of the columns to be included in the index, 
     * in order.
     */
    String columnList();

    
(Optional) Whether the index is unique.

/**
     * (Optional) Whether the index is unique.
     */
    boolean unique() default false;

}