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/*
 * Copyright (c) 2010-2015 Pivotal Software, Inc. 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. See accompanying
 * LICENSE file.
 */

package com.gemstone.gemfire.cache.query;

//import java.util.*;
import com.gemstone.gemfire.cache.*;

/**
 * An index that is built over the data stored in a GemFire {@link
 * Region}.
 * 
 * For a description of the types of indexes that GemFire currently supports,
 * see {@linkplain IndexType}.
 * 

 * An index is specified using a name, indexedExpression, fromClause, and
 * optionally a projectionAttributes.
 * 

 * The name uniquely identifies the index to for the statistics services in GemFire.
 * 

 * The indexedExpression is the lookup value for the index. The way that an
 * indexedExpression is specified and used varies depending on the type of
 * index. For more information, see {@linkplain IndexType}.
 * 

 * The fromClause specifies the collection(s) of objects that the index ranges
 * over, and must contain one and only one region path.
 * 
 * The optional projectAttributes specifies a tranformation that is done on
 * the values and is used for pre-computing a corresponding projection as
 * defined in a query.
 * 
 * @see QueryService#createIndex(String, IndexType, String, String)
 * @see IndexType
 *
 * @author Eric Zoerner
 * @since 4.0
 */
public interface Index {

  /**
   * Returns the unique name of this index
   */
  public String getName();

  /**
   * Get the index type
   * @return the type of index
   */
  public IndexType getType();
      
  /**
   * The Region this index is on
   * @return the Region for this index
   */
  public Region getRegion();
  
  /**
   * Get statistics information for this index.
   */
  public IndexStatistics getStatistics();
  
  /**
   * Get the original fromClause for this index.
   */
  public String getFromClause();
  /**
   * Get the canonicalized fromClause for this index.
   */
  public String getCanonicalizedFromClause();
  
  /**
   * Get the original indexedExpression for this index.
   */
  public String getIndexedExpression();
  
    /**
   * Get the canonicalized indexedExpression for this index.
   */
  public String getCanonicalizedIndexedExpression();
  /**
   * Get the original projectionAttributes for this expression.
   * @return the projectionAttributes, or "*" if there were none
   * specified at index creation.
   */
  public String getProjectionAttributes();
  /**
   * Get the canonicalized projectionAttributes for this expression.
   * @return the projectionAttributes, or "*" if there were none
   * specified at index creation.
   */
  public String getCanonicalizedProjectionAttributes();
}