Class KeepLastNCommitsDeletionPolicy

java.lang.Object
org.apache.lucene.index.IndexDeletionPolicy
org.apache.lucene.index.KeepLastNCommitsDeletionPolicy

public class KeepLastNCommitsDeletionPolicy extends IndexDeletionPolicy
This IndexDeletionPolicy implementation keeps the last N commits and removes all prior commits after a new commit is done. This policy can be useful for maintaining a history of recent commits while still managing index size.
  • Constructor Details

    • KeepLastNCommitsDeletionPolicy

      public KeepLastNCommitsDeletionPolicy(int numCommitsToKeep)
      Constructor that sets the number of commits to keep.
      Parameters:
      numCommitsToKeep - the number of most recent commits to retain
      Throws:
      IllegalArgumentException - if numCommitsToKeep is not positive
  • Method Details

    • onInit

      public void onInit(List<? extends IndexCommit> commits) throws IOException
      Description copied from class: IndexDeletionPolicy
      This is called once when a writer is first instantiated to give the policy a chance to remove old commit points.

      The writer locates all index commits present in the index directory and calls this method. The policy may choose to delete some of the commit points, doing so by calling method delete() of IndexCommit.

      Note: the last CommitPoint is the most recent one, i.e. the "front index state". Be careful not to delete it, unless you know for sure what you are doing, and unless you can afford to lose the index content while doing that.

      Specified by:
      onInit in class IndexDeletionPolicy
      Parameters:
      commits - List of current point-in-time commits, sorted by age (the 0th one is the oldest commit). Note that for a new index this method is invoked with an empty list.
      Throws:
      IOException
    • onCommit

      public void onCommit(List<? extends IndexCommit> commits) throws IOException
      Deletes all but the last N commits.
      Specified by:
      onCommit in class IndexDeletionPolicy
      Parameters:
      commits - List of IndexCommit, sorted by age (the 0th one is the oldest commit).
      Throws:
      IOException