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  1. Lucene - Core
  2. LUCENE-323

[PATCH] MultiFieldQueryParser and BooleanQuery do not provide adequate support for queries across multiple fields



    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 1.4
    • Fix Version/s: 1.9
    • Component/s: core/queryparser
    • Labels:
    • Environment:

      Operating System: Windows XP
      Platform: PC

    • Bugzilla Id:


      The attached test case demonstrates this problem and provides a fix:
      1. Use a custom similarity to eliminate all tf and idf effects, just to
      isolate what is being tested.
      2. Create two documents doc1 and doc2, each with two fields title and
      description. doc1 has "elephant" in title and "elephant" in description.
      doc2 has "elephant" in title and "albino" in description.
      3. Express query for "albino elephant" against both fields.
      a. MultiFieldQueryParser won't recognize either document as containing
      both terms, due to the way it expands the query across fields.
      b. Expressing query as "title:albino description:albino title:elephant
      description:elephant" will score both documents equivalently, since each
      matches two query terms.
      4. Comparison to MaxDisjunctionQuery and my method for expanding queries
      across fields. Using notation that () represents a BooleanQuery and ( | )
      represents a MaxDisjunctionQuery, "albino elephant" expands to:
      ( (title:albino | description:albino)
      (title:elephant | description:elephant) )
      This will recognize that doc2 has both terms matched while doc1 only has 1
      term matched, score doc2 over doc1.

      Refinement note: the actual expansion for "albino query" that I use is:
      ( (title:albino | description:albino)~0.1
      (title:elephant | description:elephant)~0.1 )
      This causes the score of each MaxDisjunctionQuery to be the score of highest
      scoring MDQ subclause plus 0.1 times the sum of the scores of the other MDQ
      subclauses. Thus, doc1 gets some credit for also having "elephant" in the
      description but only 1/10 as much as doc2 gets for covering another query term
      in its description. If doc3 has "elephant" in title and both "albino"
      and "elephant" in the description, then with the actual refined expansion, it
      gets the highest score of all (whereas with pure max, without the 0.1, it
      would get the same score as doc2).

      In real apps, tf's and idf's also come into play of course, but can affect
      these either way (i.e., mitigate this fundamental problem or exacerbate it).


        1. dms.tar.gz
          5 kB
          Chuck Williams
        2. DisjunctionMaxQuery.java
          10 kB
          Yonik Seeley
        3. DisjunctionMaxScorer.java
          7 kB
          Yonik Seeley
        4. TestDisjunctionMaxQuery.java
          14 kB
          Yonik Seeley
        5. TestMaxDisjunctionQuery.java
          14 kB
          Chris M. Hostetter
        6. ASF.LICENSE.NOT.GRANTED--WikipediaSimilarity.java
          2 kB
          Chuck Williams
        7. ASF.LICENSE.NOT.GRANTED--WikipediaSimilarity.java
          2 kB
          Chuck Williams
        8. ASF.LICENSE.NOT.GRANTED--WikipediaSimilarity.java
          2 kB
          Chuck Williams
        9. ASF.LICENSE.NOT.GRANTED--TestRanking.zip
          10 kB
          Miles Barr
        10. ASF.LICENSE.NOT.GRANTED--TestRanking.zip
          10 kB
          Chuck Williams
        11. ASF.LICENSE.NOT.GRANTED--TestRanking.zip
          10 kB
          Chuck Williams



            • Assignee:
              chuck@manawiz.com Chuck Williams
            • Votes:
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              0 Start watching this issue


              • Created: