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Lucene example source code file (LogByteSizeMergePolicy.java)

This example Lucene source code file (LogByteSizeMergePolicy.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_max_merge_mb, default_max_merge_mb*1024*1024, default_max_merge_mb_for_optimize, default_max_merge_mb_for_optimize*1024*1024, default_max_merge_mb_for_optimize*1024*1024, default_min_merge_mb, default_min_merge_mb*1024*1024, default_min_merge_mb*1024*1024, io, ioexception, ioexception, logbytesizemergepolicy, logbytesizemergepolicy, logmergepolicy, override

The Lucene LogByteSizeMergePolicy.java source code

package org.apache.lucene.index;

/**
 * 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.
 */

import java.io.IOException;

/** This is a {@link LogMergePolicy} that measures size of a
 *  segment as the total byte size of the segment's files. */
public class LogByteSizeMergePolicy extends LogMergePolicy {

  /** Default minimum segment size.  @see setMinMergeMB */
  public static final double DEFAULT_MIN_MERGE_MB = 1.6;

  /** Default maximum segment size.  A segment of this size
   *  or larger will never be merged.  @see setMaxMergeMB */
  public static final double DEFAULT_MAX_MERGE_MB = 2048;

  /** Default maximum segment size.  A segment of this size
   *  or larger will never be merged during optimize.  @see setMaxMergeMBForOptimize */
  public static final double DEFAULT_MAX_MERGE_MB_FOR_OPTIMIZE = Long.MAX_VALUE;

  public LogByteSizeMergePolicy() {
    minMergeSize = (long) (DEFAULT_MIN_MERGE_MB*1024*1024);
    maxMergeSize = (long) (DEFAULT_MAX_MERGE_MB*1024*1024);
    maxMergeSizeForOptimize = (long) (DEFAULT_MAX_MERGE_MB_FOR_OPTIMIZE*1024*1024);
  }
  
  @Override
  protected long size(SegmentInfo info) throws IOException {
    return sizeBytes(info);
  }

  /** <p>Determines the largest segment (measured by total
   *  byte size of the segment's files, in MB) that may be
   *  merged with other segments.  Small values (e.g., less
   *  than 50 MB) are best for interactive indexing, as this
   *  limits the length of pauses while indexing to a few
   *  seconds.  Larger values are best for batched indexing
   *  and speedier searches.</p>
   *
   *  <p>Note that {@link #setMaxMergeDocs} is also
   *  used to check whether a segment is too large for
   *  merging (it's either or).</p>*/
  public void setMaxMergeMB(double mb) {
    maxMergeSize = (long) (mb*1024*1024);
  }

  /** Returns the largest segment (measured by total byte
   *  size of the segment's files, in MB) that may be merged
   *  with other segments.
   *  @see #setMaxMergeMB */
  public double getMaxMergeMB() {
    return ((double) maxMergeSize)/1024/1024;
  }

  /** <p>Determines the largest segment (measured by total
   *  byte size of the segment's files, in MB) that may be
   *  merged with other segments during optimize. Setting
   *  it low will leave the index with more than 1 segment,
   *  even if {@link IndexWriter#optimize()} is called.*/
  public void setMaxMergeMBForOptimize(double mb) {
    maxMergeSizeForOptimize = (long) (mb*1024*1024);
  }

  /** Returns the largest segment (measured by total byte
   *  size of the segment's files, in MB) that may be merged
   *  with other segments during optimize.
   *  @see #setMaxMergeMBForOptimize */
  public double getMaxMergeMBForOptimize() {
    return ((double) maxMergeSizeForOptimize)/1024/1024;
  }

  /** 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 setMinMergeMB(double mb) {
    minMergeSize = (long) (mb*1024*1024);
  }

  /** Get the minimum size for a segment to remain
   *  un-merged.
   *  @see #setMinMergeMB **/
  public double getMinMergeMB() {
    return ((double) minMergeSize)/1024/1024;
  }
}

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