java.lang.Object
- org.apache.lucene.index.MergePolicy
- - org.apache.lucene.index.NoMergePolicy

All Implemented Interfaces:

Closeable, AutoCloseable
```
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.MergeAbortedException, MergePolicy.MergeException, MergePolicy.MergeSpecification, 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.

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

Method Summary

All Methods Instance Methods Concrete Methods
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<SegmentInfo,Boolean> segmentsToMerge)`	Determine what set of merge operations is necessary in order to merge to <= the specified segment count.
`MergePolicy.MergeSpecification`	`findMerges(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, SegmentInfo newSegment)`	Returns true if a new segment (regardless of its origin) should use the compound file format.

Methods inherited from class java.lang.Object
clone, equals, finalize, 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(SegmentInfos segmentInfos)
                                          throws CorruptIndexException,
                                                 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:
    
    segmentInfos - the total set of segments in the index
    
    Throws:
    
    CorruptIndexException
    
    IOException
  - findForcedMerges
```
public MergePolicy.MergeSpecification findForcedMerges(SegmentInfos segmentInfos,
                                                       int maxSegmentCount,
                                                       Map<SegmentInfo,Boolean> segmentsToMerge)
                                                throws CorruptIndexException,
                                                       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:
    
    CorruptIndexException
    
    IOException
  - findForcedDeletesMerges
```
public MergePolicy.MergeSpecification findForcedDeletesMerges(SegmentInfos segmentInfos)
                                                       throws CorruptIndexException,
                                                              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:
    
    CorruptIndexException
    
    IOException
  - useCompoundFile
```
public boolean useCompoundFile(SegmentInfos segments,
                               SegmentInfo newSegment)
```
    Description copied from class: MergePolicy
    
    Returns true if a new segment (regardless of its origin) should use the compound file format.
    
    Specified by:
    
    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

Class NoMergePolicy

Nested Class Summary

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

Field Summary

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

Method Summary

Methods inherited from class java.lang.Object

Field Detail

NO_COMPOUND_FILES

COMPOUND_FILES

Method Detail

close

findMerges

findForcedMerges

findForcedDeletesMerges

useCompoundFile

setIndexWriter

toString