org.apache.lucene.index
Class IndexCommit

java.lang.Object
  org.apache.lucene.index.IndexCommit

All Implemented Interfaces:

IndexCommitPoint

public abstract class IndexCommit
extends Object
implements IndexCommitPoint

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 a new and experimental and may suddenly change.

Constructor Summary

IndexCommit()

Method Summary

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	getFileNames() Returns all index files referenced by this commit point.
long	getGeneration() Returns the generation (the _N in segments_N) for this IndexCommit
abstract String	getSegmentsFileName() Get the segments file (segments_N) associated with this commit point.
long	getTimestamp() Convenience method that returns the last modified time of the segments_N file corresponding to this index commit, equivalent to getDirectory().fileModified(getSegmentsFileName()).
long	getVersion() Returns the version for this IndexCommit.
int	hashCode()
boolean	isDeleted()
boolean	isOptimized() Returns true if this commit is an optimized index.

Methods inherited from class java.lang.Object

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

Constructor Detail

IndexCommit

public IndexCommit()

Method Detail

getSegmentsFileName

public abstract String getSegmentsFileName()

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

Specified by:

getSegmentsFileName in interface IndexCommitPoint

getFileNames

public abstract Collection getFileNames()
                                 throws IOException

Returns all index files referenced by this commit point.

Specified by:

getFileNames in interface IndexCommitPoint

Throws:

IOException

getDirectory

public abstract Directory getDirectory()

Returns the Directory for the index.

delete

public 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.

Specified by:

delete in interface IndexCommitPoint

isDeleted

public boolean isDeleted()

isOptimized

public boolean isOptimized()

Returns true if this commit is an optimized index.

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

getVersion

public long getVersion()

Returns the version for this IndexCommit. This is the same value that IndexReader.getVersion() would return if it were opened on this commit.

getGeneration

public long getGeneration()

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

getTimestamp

public long getTimestamp()
                  throws IOException

Convenience method that returns the last modified time of the segments_N file corresponding to this index commit, equivalent to getDirectory().fileModified(getSegmentsFileName()).

Throws:

IOException