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  1. Lucene - Core
  2. LUCENE-5057

Hunspell stemmer generates multiple tokens



    • Type: Improvement
    • Status: Closed
    • Priority: Major
    • Resolution: Won't Fix
    • Affects Version/s: 4.3
    • Fix Version/s: None
    • Component/s: None
    • Labels:
    • Lucene Fields:


      The hunspell stemmer seems to be generating multiple tokens: the original token plus the available stems.

      It might be a good thing in some cases but it seems to be a different behaviour compared to the other stemmers and causes problems as well. I would rather have an option to decide whether it should output only the available stems, or the stems plus the original token. I'm not sure though if it's possible to have only a single stem indexed, which would be even better in my opinion. When I look at how snowball works only one token is indexed, the stem, and that works great. Probably there's something I'm missing in how hunspell works.

      Here is my issue: I have a query composed of multiple terms, which is analyzed using stemming and a boolean query is generated out of it. All fine when adding all clauses as should (OR operator), but if I add all clauses as must (AND operator), then I can get back only the documents that contain the stem originated by the exactly same original word.

      Example for the dutch language I'm working with: fiets (means bicycle in dutch), its plural is fietsen.

      If I index "fietsen" I get both "fietsen" and "fiets" indexed, but if I index "fiets" I get the only "fiets" indexed.

      When I query for "fietsen whatever" I get the following boolean query: field:fiets field:fietsen field:whatever.

      If I apply the AND operator and use must clauses for each subquery, then I can only find the documents that originally contained "fietsen", not the ones that originally contained "fiets", which is not really what stemming is about.

      Any thoughts on this? I also wonder if it can be a dictionary issue since I see that different words that have the word "fiets" as root don't get the same stems, and using the AND operator at query time is a big issue.

      I would love to contribute on this and looking forward to your feedback.




            • Assignee:
              jpountz Adrien Grand
              lucacavanna Luca Cavanna
            • Votes:
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              • Created: