Package org.elasticsearch.index.engine

Class CombinedDeletionPolicy

  • public class CombinedDeletionPolicy
extends IndexDeletionPolicy
    An IndexDeletionPolicy that coordinates between Lucene's commits and the retention of translog generation files, making sure that all translog files that are needed to recover from the Lucene commit are not deleted.

    In particular, this policy will delete index commits whose max sequence number is at most the current global checkpoint except the index commit which has the highest max sequence number among those.

    • Method Detail

      • 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
        Description copied from class: IndexDeletionPolicy

        This is called each time the writer completed a commit. This gives the policy a chance to remove old commit points with each commit.

        The policy may now choose to delete old commit points by calling method delete() of IndexCommit.

        This method is only called when IndexWriter.commit() or IndexWriter.close() is called, or possibly not at all if the IndexWriter.rollback() is called.

        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:
        onCommit in class IndexDeletionPolicy
        Parameters:
        commits - List of IndexCommit, sorted by age (the 0th one is the oldest commit).
        Throws:
        IOException

      • findSafeCommitPoint

        public static IndexCommit findSafeCommitPoint​(List<IndexCommit> commits,
                                              long globalCheckpoint)
                                       throws IOException
        Find a safe commit point from a list of existing commits based on the supplied global checkpoint. The max sequence number of a safe commit point should be at most the global checkpoint. If an index was created before 6.2 or recovered from remote, we might not have a safe commit. In this case, this method will return the oldest index commit.
        Parameters:
        commits - a list of existing commit points
        globalCheckpoint - the persisted global checkpoint from the translog, see Translog.readGlobalCheckpoint(Path, String)
        Returns:
        a safe commit or the oldest commit if a safe commit is not found
        Throws:
        IOException