[jira] [Created] (LUCENE-5030) FuzzySuggester has to operate FSTs of Unicode-letters, not UTF-8, to work correctly for 1-byte (like English) and multi-byte (non-Latin) letters

["Artem Lukanin (JIRA)" <ji...@apache.org>]

Artem Lukanin created LUCENE-5030:
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             Summary: FuzzySuggester has to operate FSTs of Unicode-letters, not UTF-8, to work correctly for 1-byte (like English) and multi-byte (non-Latin) letters
                 Key: LUCENE-5030
                 URL: https://issues.apache.org/jira/browse/LUCENE-5030
             Project: Lucene - Core
          Issue Type: Bug
    Affects Versions: 4.3
            Reporter: Artem Lukanin


There is a limitation in the current FuzzySuggester 
implementation: it computes edits in UTF-8 space instead of Unicode 
character (code point) space. 

This should be fixable: we'd need to fix TokenStreamToAutomaton to 
work in Unicode character space, then fix FuzzySuggester to do the 
same steps that FuzzyQuery does: do the LevN expansion in Unicode 
character space, then convert that automaton to UTF-8, then intersect 
with the suggest FST.

See the discussion here: http://lucene.472066.n3.nabble.com/minFuzzyLength-in-FuzzySuggester-behaves-differently-for-English-and-Russian-td4067018.html#none

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