lucene/codecs/src/java/org/apache/lucene/codecs/memory/DirectDocValuesFormat.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.lucene.codecs.memory;


import java.io.IOException;

import org.apache.lucene.codecs.DocValuesConsumer;
import org.apache.lucene.codecs.DocValuesFormat;
import org.apache.lucene.codecs.DocValuesProducer;
import org.apache.lucene.document.SortedSetDocValuesField; // javadocs
import org.apache.lucene.index.SegmentReadState;
import org.apache.lucene.index.SegmentWriteState;
import org.apache.lucene.util.ArrayUtil;

/** In-memory docvalues format that does no (or very little)
 *  compression.  Indexed values are stored on disk, but
 *  then at search time all values are loaded into memory as
 *  simple java arrays.  For numeric values, it uses
 *  byte[], short[], int[], long[] as necessary to fit the
 *  range of the values.  For binary values, there is an int
 *  (4 bytes) overhead per value.
 *
 *  <p>Limitations:
 *  <ul>
 *    <li>For binary and sorted fields the total space
 *        required for all binary values cannot exceed about
 *        2.1 GB (see #MAX_TOTAL_BYTES_LENGTH).</li>
 *
 *    <li>For sorted set fields, the sum of the size of each
 *        document's set of values cannot exceed about 2.1 B
 *        values (see #MAX_SORTED_SET_ORDS).  For example,
 *        if every document has 10 values (10 instances of
 *        {@link SortedSetDocValuesField}) added, then no
 *        more than ~210 M documents can be added to one
 *        segment. </li>
 *  </ul> */

public class DirectDocValuesFormat extends DocValuesFormat {

  /** The sum of all byte lengths for binary field, or for
   *  the unique values in sorted or sorted set fields, cannot
   *  exceed this. */
  public final static int MAX_TOTAL_BYTES_LENGTH = ArrayUtil.MAX_ARRAY_LENGTH;

  /** The sum of the number of values across all documents
   *  in a sorted set field cannot exceed this. */
  public final static int MAX_SORTED_SET_ORDS = ArrayUtil.MAX_ARRAY_LENGTH;

  /** Sole constructor. */
  public DirectDocValuesFormat() {
    super("Direct");
  }
  
  @Override
  public DocValuesConsumer fieldsConsumer(SegmentWriteState state) throws IOException {
    return new DirectDocValuesConsumer(state, DATA_CODEC, DATA_EXTENSION, METADATA_CODEC, METADATA_EXTENSION);
  }
  
  @Override
  public DocValuesProducer fieldsProducer(SegmentReadState state) throws IOException {
    return new DirectDocValuesProducer(state, DATA_CODEC, DATA_EXTENSION, METADATA_CODEC, METADATA_EXTENSION);
  }
  
  static final String DATA_CODEC = "DirectDocValuesData";
  static final String DATA_EXTENSION = "dvdd";
  static final String METADATA_CODEC = "DirectDocValuesMetadata";
  static final String METADATA_EXTENSION = "dvdm";
}