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.MergeException, MergePolicy.MergeSpecification, MergePolicy.OneMerge

Field Summary

Fields

Modifier and Type	Field and Description
static double	DEFAULT_MAX_MERGE_MB Default maximum segment size.
static double	DEFAULT_MIN_MERGE_MB Default minimum segment size.

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

DEFAULT_MAX_MERGE_DOCS, DEFAULT_MERGE_FACTOR, LEVEL_LOG_SPAN

Constructor Summary

Constructors

Constructor and Description
LogByteSizeMergePolicy()

Method Summary

Modifier and Type	Method and Description
double	getMaxMergeMB() Returns the largest segment (meaured by total byte size of the segment's files, in MB) that may be merged with other segments.
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	setMinMergeMB(double mb) Sets the minimum size for the lowest level segments.

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

close, findMerges, findMergesForOptimize, getMaxMergeDocs, getMergeFactor, getUseCompoundDocStore, getUseCompoundFile, setMaxMergeDocs, setMergeFactor, setUseCompoundDocStore, setUseCompoundFile, useCompoundDocStore, useCompoundFile

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, 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

Constructor Detail

LogByteSizeMergePolicy

public LogByteSizeMergePolicy()

Method Detail

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 (meaured by total byte size of the segment's files, in MB) that may be merged with other segments.

See Also:

setMaxMergeMB(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)