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Lucene example source code file (LogDocMergePolicy.java)

This example Lucene source code file (LogDocMergePolicy.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

default_min_merge_docs, default_min_merge_docs, io, ioexception, ioexception, logdocmergepolicy, logdocmergepolicy, logmergepolicy, logmergepolicy, override

The Lucene LogDocMergePolicy.java source code

package org.apache.lucene.index;

import java.io.IOException;

/**
 * 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.
 */

/** This is a {@link LogMergePolicy} that measures size of a
 *  segment as the number of documents (not taking deletions
 *  into account). */

public class LogDocMergePolicy extends LogMergePolicy {

  /** Default minimum segment size.  @see setMinMergeDocs */
  public static final int DEFAULT_MIN_MERGE_DOCS = 1000;

  public LogDocMergePolicy() {
    minMergeSize = DEFAULT_MIN_MERGE_DOCS;
    
    // maxMergeSize(ForOptimize) are never used by LogDocMergePolicy; set
    // it to Long.MAX_VALUE to disable it
    maxMergeSize = Long.MAX_VALUE;
    maxMergeSizeForOptimize = Long.MAX_VALUE;
  }

  @Override
  protected long size(SegmentInfo info) throws IOException {
    return sizeDocs(info);
  }

  /** Sets the minimum size for the lowest level segments.
   * Any segments below this size are considered to be on
   * the same level (even if they vary drastically in size)
   * and will be merged whenever there are mergeFactor of
   * them.  This effectively truncates the "long tail" of
   * small segments that would otherwise be created into a
   * single level.  If you set this too large, it could
   * greatly increase the merging cost during indexing (if
   * you flush many small segments). */
  public void setMinMergeDocs(int minMergeDocs) {
    minMergeSize = minMergeDocs;
  }

  /** Get the minimum size for a segment to remain
   *  un-merged.
   *  @see #setMinMergeDocs **/
  public int getMinMergeDocs() {
    return (int) minMergeSize;
  }
}

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