Package org.apache.lucene.index

Class LogByteSizeMergePolicy

  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable, java.lang.Cloneable
    public class LogByteSizeMergePolicy
extends LogMergePolicy
    This is a LogMergePolicy that measures size of a segment as the total byte size of the segment's files.

    • Field Detail

      • DEFAULT_MIN_MERGE_MB

        public static final double DEFAULT_MIN_MERGE_MB
        Default minimum segment size. @see setMinMergeMB
        See Also:
        Constant Field Values

      • DEFAULT_MAX_MERGE_MB

        public static final double DEFAULT_MAX_MERGE_MB
        Default maximum segment size. A segment of this size or larger will never be merged. @see setMaxMergeMB
        See Also:
        Constant Field Values

      • DEFAULT_MAX_MERGE_MB_FOR_FORCED_MERGE

        public static final double DEFAULT_MAX_MERGE_MB_FOR_FORCED_MERGE
        Default maximum segment size. A segment of this size or larger will never be merged during forceMerge. @see setMaxMergeMBForForceMerge
        See Also:
        Constant Field Values

    • Constructor Detail

      • LogByteSizeMergePolicy

        public LogByteSizeMergePolicy()
        Sole constructor, setting all settings to their defaults.

    • Method Detail

      • setMaxMergeMB

        public void setMaxMergeMB​(double mb)

        Determines the largest segment (measured by total byte size of the segment's files, in MB) that may be merged with other segments. Small values (e.g., less than 50 MB) are best for interactive indexing, as this limits the length of pauses while indexing to a few seconds. Larger values are best for batched indexing and speedier searches.

        Note that LogMergePolicy.setMaxMergeDocs(int) is also used to check whether a segment is too large for merging (it's either or).

      • getMaxMergeMB

        public double getMaxMergeMB()
        Returns the largest segment (measured by total byte size of the segment's files, in MB) that may be merged with other segments.
        See Also:
        setMaxMergeMB(double)

      • setMaxMergeMBForForcedMerge

        public void setMaxMergeMBForForcedMerge​(double mb)

        Determines the largest segment (measured by total byte size of the segment's files, in MB) that may be merged with other segments during forceMerge. Setting it low will leave the index with more than 1 segment, even if IndexWriter.forceMerge(int) is called.

      • getMaxMergeMBForForcedMerge

        public double getMaxMergeMBForForcedMerge()
        Returns the largest segment (measured by total byte size of the segment's files, in MB) that may be merged with other segments during forceMerge.
        See Also:
        setMaxMergeMBForForcedMerge(double)

      • setMinMergeMB

        public void setMinMergeMB​(double mb)
        Sets the minimum size for the lowest level segments. Any segments below this size are considered to be on the same level (even if they vary drastically in size) and will be merged whenever there are mergeFactor of them. This effectively truncates the "long tail" of small segments that would otherwise be created into a single level. If you set this too large, it could greatly increase the merging cost during indexing (if you flush many small segments).

      • getMinMergeMB

        public double getMinMergeMB()
        Get the minimum size for a segment to remain un-merged.
        See Also:
        setMinMergeMB(double)