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  1. Lucene - Core
  2. LUCENE-296

[PATCH] FuzzyTermEnum optimization and refactor


    • Improvement
    • Status: Closed
    • Minor
    • Resolution: Fixed
    • None
    • None
    • core/search
    • None
    • Operating System: All
      Platform: All

    • 31882


      I took a look at it to see if it could be improved. I saw speed improvements of
      20% - 40% by making a couple changes.

      The patch is here: http://www.hagerfamily.com/patches/FuzzyTermEnumOptimizePatch.txt

      The Patch is based on the HEAD of the CVS tree as of Oct 22, 2004.

      What Changed?

      Since the word was discarded if the edit distance for the word was
      above a certain threshold, I updated the distance algorithm to abort
      if at any time during the calculation it is determined that the best
      possible outcome of the edit distance algorithm is above this
      threshold. The source code has a great explanation.

      I also reduced the amount of floating point math, reduced the amount
      of potential space the array takes in its first dimension, removed the
      potential divide by 0 error when one term is an empty string, and
      fixed a bug where an IllegalArgumentException was thrown if the class
      was somehow initialized wrong, instead of looking at the arguments.

      The behavior is almost identical. The exception is that similarity is
      set to 0.0 when it is guaranteed to be below the minimum similarity.


      I saw the biggest improvement from longer words, which makes a sense.
      My long word was "bridgetown" and I saw a 60% improvement on this.
      The biggest improvement are for words that are farthest away from the
      median length of the words in the index. Short words (1-3 characters)
      saw a 30% improvement. Medium words saw a 10% improvement (5-7
      characters). These improvements are with the prefix set to 0.




            java-dev@lucene.apache.org Lucene Developers
            jhager@gmail.com Jonathan Hager
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