org.apache.lucene.index.sorter

Class SortingMergePolicy

java.lang.Object

org.apache.lucene.index.MergePolicy

org.apache.lucene.index.sorter.SortingMergePolicy

All Implemented Interfaces:

Closeable, AutoCloseable, Cloneable

public final class SortingMergePolicy
extends MergePolicy

A MergePolicy that reorders documents according to a Sorter before merging them. As a consequence, all segments resulting from a merge will be sorted while segments resulting from a flush will be in the order in which documents have been added.

NOTE: Never use this MergePolicy if you rely on IndexWriter.addDocuments(Iterable, org.apache.lucene.analysis.Analyzer) to have sequentially-assigned doc IDs, this policy will scatter doc IDs.

NOTE: This MergePolicy should only be used with idempotent Sorters so that the order of segments is predictable. For example, using SortingMergePolicy with Sorter.REVERSE_DOCS (which is not idempotent) will make the order of documents in a segment depend on the number of times the segment has been merged.

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 and Description
static String	SORTER_ID_PROP Put in the diagnostics to denote that this segment is sorted.

Constructor Summary

Constructors

Constructor and Description
SortingMergePolicy(MergePolicy in, Sorter sorter) Create a new MergePolicy that sorts documents with sorter.

Method Summary

Modifier and Type	Method and Description
MergePolicy	clone()
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.
static boolean	isSorted(AtomicReader reader, Sorter sorter) Returns true if the given reader is sorted by the given sorter.
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

getMaxCFSSegmentSizeMB, getNoCFSRatio, setMaxCFSSegmentSizeMB, setNoCFSRatio

Methods inherited from class java.lang.Object

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

Field Detail

SORTER_ID_PROP

public static final String SORTER_ID_PROP

Put in the diagnostics to denote that this segment is sorted.

See Also:

Constant Field Values

Constructor Detail

SortingMergePolicy

public SortingMergePolicy(MergePolicy in,
                          Sorter sorter)

Create a new MergePolicy that sorts documents with sorter.

Method Detail

isSorted

public static boolean isSorted(AtomicReader reader,
                               Sorter sorter)

Returns true if the given reader is sorted by the given sorter.

findMerges

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

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

Throws:

IOException

findForcedMerges

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

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.

Throws:

IOException

findForcedDeletesMerges

public MergePolicy.MergeSpecification findForcedDeletesMerges(SegmentInfos segmentInfos)
                                                       throws IOException

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

Throws:

IOException

clone

public MergePolicy clone()

Overrides:

clone in class MergePolicy

close

public void close()

Description copied from class: MergePolicy

Release all resources for the policy.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in class MergePolicy

useCompoundFile

public boolean useCompoundFile(SegmentInfos segments,
                               SegmentCommitInfo newSegment)
                        throws IOException

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

Throws:

IOException

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