Package org.apache.lucene.index

Class IndexCommit

java.lang.Object
org.apache.lucene.index.IndexCommit
All Implemented Interfaces:
Comparable<IndexCommit>
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.

  • Method Details

    • 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>