org.apache.lucene.index

Class IndexCommit

java.lang.Object

org.apache.lucene.index.IndexCommit

All Implemented Interfaces:

Comparable<IndexCommit>

Direct Known Subclasses:

SnapshotDeletionPolicy.SnapshotCommitPoint

public abstract class IndexCommit
extends Object
implements Comparable<IndexCommit>

Expert: represents a single commit into an index as seen by the IndexDeletionPolicy or IndexReader.

Changes to the content of an index are made visible only after the writer who made that change commits by writing a new segments file (segments_N). This point in time, when the action of writing of a new segments file to the directory is completed, is an index commit.

Each index commit point has a unique segments file associated with it. The segments file associated with a later index commit point would have a larger N.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	IndexCommit() Sole constructor.

Method Summary

Methods

Modifier and Type	Method and Description
int	compareTo(IndexCommit commit)
abstract void	delete() Delete this commit point.
boolean	equals(Object other) Two IndexCommits are equal if both their Directory and versions are equal.
abstract Directory	getDirectory() Returns the Directory for the index.
abstract Collection<String>	getFileNames() Returns all index files referenced by this commit point.
abstract long	getGeneration() Returns the generation (the _N in segments_N) for this IndexCommit
abstract int	getSegmentCount() Returns number of segments referenced by this commit.
abstract String	getSegmentsFileName() Get the segments file (segments_N) associated with this commit point.
abstract Map<String,String>	getUserData() Returns userData, previously passed to IndexWriter.setCommitData(Map) for this commit.
int	hashCode()
abstract boolean	isDeleted() Returns true if this commit should be deleted; this is only used by IndexWriter after invoking the IndexDeletionPolicy.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

IndexCommit

protected IndexCommit()

Sole constructor. (For invocation by subclass constructors, typically implicit.)

Method Detail

getSegmentsFileName

public abstract String getSegmentsFileName()

Get the segments file (segments_N) associated with this commit point.

getFileNames

public abstract Collection<String> getFileNames()
                                         throws IOException

Returns all index files referenced by this commit point.

Throws:

IOException

getDirectory

public abstract Directory getDirectory()

Returns the Directory for the index.

delete

public abstract void delete()

Delete this commit point. This only applies when using the commit point in the context of IndexWriter's IndexDeletionPolicy.

Upon calling this, the writer is notified that this commit point should be deleted.

Decision that a commit-point should be deleted is taken by the IndexDeletionPolicy in effect and therefore this should only be called by its onInit() or onCommit() methods.

isDeleted

public abstract boolean isDeleted()

Returns true if this commit should be deleted; this is only used by IndexWriter after invoking the IndexDeletionPolicy.

getSegmentCount

public abstract int getSegmentCount()

Returns number of segments referenced by this commit.

equals

public boolean equals(Object other)

Two IndexCommits are equal if both their Directory and versions are equal.

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

getGeneration

public abstract long getGeneration()

Returns the generation (the _N in segments_N) for this IndexCommit

getUserData

public abstract Map<String,String> getUserData()
                                        throws IOException

Returns userData, previously passed to IndexWriter.setCommitData(Map) for this commit. Map is String -> String.

Throws:

IOException

compareTo

public int compareTo(IndexCommit commit)

Specified by:

compareTo in interface Comparable<IndexCommit>