org.apache.lucene.index
Class LogByteSizeMergePolicy

java.lang.Object
  extended by org.apache.lucene.index.MergePolicy
      extended by org.apache.lucene.index.LogMergePolicy
          extended by org.apache.lucene.index.LogByteSizeMergePolicy
All Implemented Interfaces:
Closeable
Direct Known Subclasses:
BalancedSegmentMergePolicy

public class LogByteSizeMergePolicy
extends LogMergePolicy

This is a LogMergePolicy that measures size of a segment as the total byte size of the segment's files.


Nested Class Summary
 
Nested classes/interfaces inherited from class org.apache.lucene.index.MergePolicy
MergePolicy.MergeAbortedException, MergePolicy.MergeException, MergePolicy.MergeSpecification, MergePolicy.OneMerge
 
Field Summary
static double DEFAULT_MAX_MERGE_MB
          Default maximum segment size.
static double DEFAULT_MAX_MERGE_MB_FOR_OPTIMIZE
          Default maximum segment size.
static double DEFAULT_MIN_MERGE_MB
          Default minimum segment size.
 
Fields inherited from class org.apache.lucene.index.LogMergePolicy
calibrateSizeByDeletes, DEFAULT_MAX_MERGE_DOCS, DEFAULT_MERGE_FACTOR, DEFAULT_NO_CFS_RATIO, LEVEL_LOG_SPAN, maxMergeDocs, maxMergeSize, maxMergeSizeForOptimize, mergeFactor, minMergeSize, noCFSRatio, useCompoundFile
 
Fields inherited from class org.apache.lucene.index.MergePolicy
writer
 
Constructor Summary
LogByteSizeMergePolicy()
           
 
Method Summary
 double getMaxMergeMB()
          Returns the largest segment (measured by total byte size of the segment's files, in MB) that may be merged with other segments.
 double getMaxMergeMBForOptimize()
          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.
 double getMinMergeMB()
          Get the minimum size for a segment to remain un-merged.
 void setMaxMergeMB(double mb)
          Determines the largest segment (measured by total byte size of the segment's files, in MB) that may be merged with other segments.
 void setMaxMergeMBForOptimize(double mb)
          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.
 void setMinMergeMB(double mb)
          Sets the minimum size for the lowest level segments.
protected  long size(SegmentInfo info)
           
 
Methods inherited from class org.apache.lucene.index.LogMergePolicy
close, findMerges, findMergesForOptimize, findMergesToExpungeDeletes, getCalibrateSizeByDeletes, getMaxMergeDocs, getMergeFactor, getNoCFSRatio, getUseCompoundFile, isOptimized, isOptimized, message, setCalibrateSizeByDeletes, setMaxMergeDocs, setMergeFactor, setNoCFSRatio, setUseCompoundFile, sizeBytes, sizeDocs, toString, useCompoundFile, verbose
 
Methods inherited from class org.apache.lucene.index.MergePolicy
setIndexWriter
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

DEFAULT_MIN_MERGE_MB

public static final double DEFAULT_MIN_MERGE_MB
Default minimum segment size. @see setMinMergeMB

See Also:
Constant Field Values

DEFAULT_MAX_MERGE_MB

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

See Also:
Constant Field Values

DEFAULT_MAX_MERGE_MB_FOR_OPTIMIZE

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

See Also:
Constant Field Values
Constructor Detail

LogByteSizeMergePolicy

public LogByteSizeMergePolicy()
Method Detail

size

protected long size(SegmentInfo info)
             throws IOException
Specified by:
size in class LogMergePolicy
Throws:
IOException

setMaxMergeMB

public void setMaxMergeMB(double mb)

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.

Note that LogMergePolicy.setMaxMergeDocs(int) is also used to check whether a segment is too large for merging (it's either or).


getMaxMergeMB

public double getMaxMergeMB()
Returns the largest segment (measured by total byte size of the segment's files, in MB) that may be merged with other segments.

See Also:
setMaxMergeMB(double)

setMaxMergeMBForOptimize

public void setMaxMergeMBForOptimize(double mb)

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 IndexWriter.optimize() is called.


getMaxMergeMBForOptimize

public double getMaxMergeMBForOptimize()
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 Also:
setMaxMergeMBForOptimize(double)

setMinMergeMB

public void setMinMergeMB(double mb)
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).


getMinMergeMB

public double getMinMergeMB()
Get the minimum size for a segment to remain un-merged.

See Also:
setMinMergeMB(double)


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