Package org.apache.lucene.index

Class NoMergePolicy

java.lang.Object

org.apache.lucene.index.MergePolicy

org.apache.lucene.index.NoMergePolicy

All Implemented Interfaces:

Closeable, AutoCloseable, Cloneable

public final class NoMergePolicy
extends MergePolicy

A MergePolicy which never returns merges to execute (hence it's name). It is also a singleton and can be accessed through NO_COMPOUND_FILES if you want to indicate the index does not use compound files, or through COMPOUND_FILES otherwise. Use it if you want to prevent an IndexWriter from ever executing merges, without going through the hassle of tweaking a merge policy's settings to achieve that, such as changing its merge factor.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.index.MergePolicy

MergePolicy.DocMap, MergePolicy.MergeAbortedException, MergePolicy.MergeException, MergePolicy.MergeSpecification, MergePolicy.MergeTrigger, MergePolicy.OneMerge

Field Summary

Fields

Modifier and Type	Field	Description
static MergePolicy	COMPOUND_FILES	A singleton NoMergePolicy which indicates the index uses compound files.
static MergePolicy	NO_COMPOUND_FILES	A singleton NoMergePolicy which indicates the index does not use compound files.

Method Summary

Modifier and Type	Method	Description
void	close()	Release all resources for the policy.
MergePolicy.MergeSpecification	findForcedDeletesMerges(SegmentInfos segmentInfos)	Determine what set of merge operations is necessary in order to expunge all deletes from the index.
MergePolicy.MergeSpecification	findForcedMerges(SegmentInfos segmentInfos, int maxSegmentCount, Map<SegmentCommitInfo,Boolean> segmentsToMerge)	Determine what set of merge operations is necessary in order to merge to <= the specified segment count.
MergePolicy.MergeSpecification	findMerges(MergePolicy.MergeTrigger mergeTrigger, SegmentInfos segmentInfos)	Determine what set of merge operations are now necessary on the index.
void	setIndexWriter(IndexWriter writer)	Sets the IndexWriter to use by this merge policy.
String	toString()
boolean	useCompoundFile(SegmentInfos segments, SegmentCommitInfo newSegment)	Returns true if a new segment (regardless of its origin) should use the compound file format.

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

clone, getMaxCFSSegmentSizeMB, getNoCFSRatio, setMaxCFSSegmentSizeMB, setNoCFSRatio

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

NO_COMPOUND_FILES

public static final MergePolicy NO_COMPOUND_FILES

A singleton NoMergePolicy which indicates the index does not use compound files.

COMPOUND_FILES

public static final MergePolicy COMPOUND_FILES

A singleton NoMergePolicy which indicates the index uses compound files.

Method Detail

close

public void close()

Description copied from class: MergePolicy

Release all resources for the policy.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Specified by:

close in class MergePolicy

findMerges

public MergePolicy.MergeSpecification findMerges(MergePolicy.MergeTrigger mergeTrigger,
                                                 SegmentInfos segmentInfos)

Description copied from class: MergePolicy

Determine what set of merge operations are now necessary on the index. IndexWriter calls this whenever there is a change to the segments. This call is always synchronized on the IndexWriter instance so only one thread at a time will call this method.

Specified by:

findMerges in class MergePolicy

Parameters:

mergeTrigger - the event that triggered the merge

segmentInfos - the total set of segments in the index

findForcedMerges

public MergePolicy.MergeSpecification findForcedMerges(SegmentInfos segmentInfos,
                                                       int maxSegmentCount,
                                                       Map<SegmentCommitInfo,Boolean> segmentsToMerge)

Description copied from class: MergePolicy

Determine what set of merge operations is necessary in order to merge to <= the specified segment count. IndexWriter calls this when its IndexWriter.forceMerge(int) method is called. This call is always synchronized on the IndexWriter instance so only one thread at a time will call this method.

Specified by:

findForcedMerges in class MergePolicy

Parameters:

segmentInfos - the total set of segments in the index

maxSegmentCount - requested maximum number of segments in the index (currently this is always 1)

segmentsToMerge - contains the specific SegmentInfo instances that must be merged away. This may be a subset of all SegmentInfos. If the value is True for a given SegmentInfo, that means this segment was an original segment present in the to-be-merged index; else, it was a segment produced by a cascaded merge.

findForcedDeletesMerges

public MergePolicy.MergeSpecification findForcedDeletesMerges(SegmentInfos segmentInfos)

Description copied from class: MergePolicy

Determine what set of merge operations is necessary in order to expunge all deletes from the index.

Specified by:

findForcedDeletesMerges in class MergePolicy

Parameters:

segmentInfos - the total set of segments in the index

useCompoundFile

public boolean useCompoundFile(SegmentInfos segments,
                               SegmentCommitInfo newSegment)

Description copied from class: MergePolicy

Returns true if a new segment (regardless of its origin) should use the compound file format. The default implementation returns true iff the size of the given mergedInfo is less or equal to MergePolicy.getMaxCFSSegmentSizeMB() and the size is less or equal to the TotalIndexSize * MergePolicy.getNoCFSRatio() otherwise false.

Overrides:

useCompoundFile in class MergePolicy

setIndexWriter

public void setIndexWriter(IndexWriter writer)

Description copied from class: MergePolicy

Sets the IndexWriter to use by this merge policy. This method is allowed to be called only once, and is usually set by IndexWriter. If it is called more than once, SetOnce.AlreadySetException is thrown.

Overrides:

setIndexWriter in class MergePolicy

See Also:

SetOnce

toString

public String toString()

Overrides:

toString in class Object