org.apache.lucene.index

Class LogByteSizeMergePolicy

java.lang.Object

org.apache.lucene.index.MergePolicy

org.apache.lucene.index.LogMergePolicy

org.apache.lucene.index.LogByteSizeMergePolicy

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.MergeContext, MergePolicy.MergeException, MergePolicy.MergeSpecification, MergePolicy.OneMerge, MergePolicy.OneMergeProgress

Field Summary

Fields

Modifier and Type	Field and Description
static double	DEFAULT_MAX_MERGE_MB Default maximum segment size.
static double	DEFAULT_MAX_MERGE_MB_FOR_FORCED_MERGE 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, maxMergeSizeForForcedMerge, mergeFactor, minMergeSize

Fields inherited from class org.apache.lucene.index.MergePolicy

DEFAULT_MAX_CFS_SEGMENT_SIZE, maxCFSSegmentSize, noCFSRatio

Constructor Summary

Constructors

Constructor and Description
LogByteSizeMergePolicy() Sole constructor, setting all settings to their defaults.

Method Summary

Modifier and Type	Method and Description
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	getMaxMergeMBForForcedMerge() Returns the largest segment (measured by total byte size of the segment's files, in MB) that may be merged with other segments during forceMerge.
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	setMaxMergeMBForForcedMerge(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 forceMerge.
void	setMinMergeMB(double mb) Sets the minimum size for the lowest level segments.
protected long	size(SegmentCommitInfo info, MergePolicy.MergeContext mergeContext) Return the byte size of the provided SegmentCommitInfo, pro-rated by percentage of non-deleted documents is set.

Methods inherited from class org.apache.lucene.index.LogMergePolicy

findForcedDeletesMerges, findForcedMerges, findMerges, getCalibrateSizeByDeletes, getMaxMergeDocs, getMergeFactor, isMerged, setCalibrateSizeByDeletes, setMaxMergeDocs, setMergeFactor, sizeBytes, sizeDocs, toString

Methods inherited from class org.apache.lucene.index.MergePolicy

assertDelCount, findFullFlushMerges, getMaxCFSSegmentSizeMB, getNoCFSRatio, isMerged, keepFullyDeletedSegment, message, numDeletesToMerge, segString, setMaxCFSSegmentSizeMB, setNoCFSRatio, useCompoundFile, verbose

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_FORCED_MERGE

public static final double DEFAULT_MAX_MERGE_MB_FOR_FORCED_MERGE

Default maximum segment size. A segment of this size or larger will never be merged during forceMerge. @see setMaxMergeMBForForceMerge

See Also:

Constant Field Values

Constructor Detail

LogByteSizeMergePolicy

public LogByteSizeMergePolicy()

Sole constructor, setting all settings to their defaults.

Method Detail

size

protected long size(SegmentCommitInfo info,
                    MergePolicy.MergeContext mergeContext)
             throws IOException

Description copied from class: MergePolicy

Return the byte size of the provided SegmentCommitInfo, pro-rated by percentage of non-deleted documents is set.

Overrides:

size in class MergePolicy

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)

setMaxMergeMBForForcedMerge

public void setMaxMergeMBForForcedMerge(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 forceMerge. Setting it low will leave the index with more than 1 segment, even if IndexWriter.forceMerge(int) is called.

getMaxMergeMBForForcedMerge

public double getMaxMergeMBForForcedMerge()

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

See Also:

setMaxMergeMBForForcedMerge(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)