C# Class Lucene.Net.Index.MergePolicy

Expert: a MergePolicy determines the sequence of primitive merge operations to be used for overall merge and optimize operations.

Whenever the segments in an index have been altered by {@link IndexWriter}, either the addition of a newly flushed segment, addition of many segments from addIndexes* calls, or a previous merge that may now need to cascade, {@link IndexWriter} invokes {@link #findMerges} to give the MergePolicy a chance to pick merges that are now required. This method returns a {@link MergeSpecification} instance describing the set of merges that should be done, or null if no merges are necessary. When IndexWriter.optimize is called, it calls {@link #findMergesForOptimize} and the MergePolicy should then return the necessary merges.

Note that the policy can return more than one merge at a time. In this case, if the writer is using {@link SerialMergeScheduler}, the merges will be run sequentially but if it is using {@link ConcurrentMergeScheduler} they will be run concurrently.

The default MergePolicy is {@link LogByteSizeMergePolicy}.

NOTE: This API is new and still experimental (subject to change suddenly in the next release)

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Protected Properties

Property	Type	Description
DEFAULT_MAX_CFS_SEGMENT_SIZE	long
MaxCFSSegmentSize	long
NoCFSRatio_Renamed	double
Writer	SetOnce

Public Methods

Method	Description
Clone ( ) : object
Dispose ( ) : void	Release all resources for the policy.
FindForcedDeletesMerges ( SegmentInfos segmentInfos ) : MergeSpecification	Determine what set of merge operations is necessary in order to expunge all deletes from the index.
FindForcedMerges ( SegmentInfos segmentInfos, int maxSegmentCount, bool?>.IDictionary segmentsToMerge ) : MergeSpecification	Determine what set of merge operations is necessary in order to merge to <= the specified segment count. IndexWriter calls this when its IndexWriter#forceMerge method is called. this call is always synchronized on the IndexWriter instance so only one thread at a time will call this method.
FindMerges ( MergeTrigger mergeTrigger, SegmentInfos segmentInfos ) : MergeSpecification	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.
MergePolicy ( ) : System	Creates a new merge policy instance. Note that if you intend to use it without passing it to IndexWriter, you should call #setIndexWriter(IndexWriter).
UseCompoundFile ( SegmentInfos infos, Lucene.Net.Index.SegmentCommitInfo mergedInfo ) : bool	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 #getMaxCFSSegmentSizeMB() and the size is less or equal to the TotalIndexSize * #getNoCFSRatio() otherwise `false`.

Protected Methods

Method	Description
IsMerged ( SegmentInfos infos, Lucene.Net.Index.SegmentCommitInfo info ) : bool	Returns true if this single info is already fully merged (has no pending deletes, is in the same dir as the writer, and matches the current compound file setting
MergePolicy ( double defaultNoCFSRatio, long defaultMaxCFSSegmentSize ) : System	Creates a new merge policy instance with default settings for noCFSRatio and maxCFSSegmentSize. this ctor should be used by subclasses using different defaults than the MergePolicy
Size ( Lucene.Net.Index.SegmentCommitInfo info ) : long	Return the byte size of the provided {@link SegmentCommitInfo}, pro-rated by percentage of non-deleted documents is set.

Method Details

Clone() public method

public Clone ( ) : object
return	object

Dispose() public abstract method

Release all resources for the policy.

public abstract Dispose ( ) : void
return	void

FindForcedDeletesMerges() public abstract method

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

public abstract FindForcedDeletesMerges ( SegmentInfos segmentInfos ) : MergeSpecification
segmentInfos	SegmentInfos	/// the total set of segments in the index
return	MergeSpecification

FindForcedMerges() public abstract method

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

public abstract FindForcedMerges ( SegmentInfos segmentInfos, int maxSegmentCount, bool?>.IDictionary segmentsToMerge ) : MergeSpecification
segmentInfos	SegmentInfos	/// the total set of segments in the index
maxSegmentCount	int	/// requested maximum number of segments in the index (currently this /// is always 1)
segmentsToMerge	bool?>.IDictionary	/// 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.
return	MergeSpecification

FindMerges() public abstract method

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.

public abstract FindMerges ( MergeTrigger mergeTrigger, SegmentInfos segmentInfos ) : MergeSpecification
mergeTrigger	MergeTrigger	the event that triggered the merge
segmentInfos	SegmentInfos	/// the total set of segments in the index
return	MergeSpecification

IsMerged() protected method

Returns true if this single info is already fully merged (has no pending deletes, is in the same dir as the writer, and matches the current compound file setting

protected IsMerged ( SegmentInfos infos, Lucene.Net.Index.SegmentCommitInfo info ) : bool
infos	SegmentInfos
info	Lucene.Net.Index.SegmentCommitInfo
return	bool

MergePolicy() public method

Creates a new merge policy instance. Note that if you intend to use it without passing it to IndexWriter, you should call #setIndexWriter(IndexWriter).

public MergePolicy ( ) : System
return	System

MergePolicy() protected method

Creates a new merge policy instance with default settings for noCFSRatio and maxCFSSegmentSize. this ctor should be used by subclasses using different defaults than the MergePolicy

protected MergePolicy ( double defaultNoCFSRatio, long defaultMaxCFSSegmentSize ) : System
defaultNoCFSRatio	double
defaultMaxCFSSegmentSize	long
return	System

Size() protected method

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

protected Size ( Lucene.Net.Index.SegmentCommitInfo info ) : long
info	Lucene.Net.Index.SegmentCommitInfo
return	long

UseCompoundFile() public method

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 #getMaxCFSSegmentSizeMB() and the size is less or equal to the TotalIndexSize * #getNoCFSRatio() otherwise false.

public UseCompoundFile ( SegmentInfos infos, Lucene.Net.Index.SegmentCommitInfo mergedInfo ) : bool
infos	SegmentInfos
mergedInfo	Lucene.Net.Index.SegmentCommitInfo
return	bool

Property Details

DEFAULT_MAX_CFS_SEGMENT_SIZE protected_oe static_oe property

Default max segment size in order to use compound file system. Set to Long#MAX_VALUE.

protected static long DEFAULT_MAX_CFS_SEGMENT_SIZE
return	long

MaxCFSSegmentSize protected_oe property

If the size of the merged segment exceeds this value then it will not use compound file format.

protected long MaxCFSSegmentSize
return	long

NoCFSRatio_Renamed protected_oe property

If the size of the merge segment exceeds this ratio of the total index size then it will remain in non-compound format

protected double NoCFSRatio_Renamed
return	double

Writer protected_oe property

IndexWriter that contains this instance.

protected SetOnce Writer
return	SetOnce