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https://issues.apache.org/jira/browse/LUCENE-1224?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12638423#action_12638423
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Todd Feak commented on LUCENE-1224:
-----------------------------------

This bug caused me *major* headaches trying to figure out why substring 
matching with an NGramTokenFilter wasn't working for anything other then when 
setting min and max to the same values. 

The patch seems to fix the issue when applied locally, however it also has a 
bug in it. It will stop parsing a token stream if a token comes through that is 
less then the minGramSize, even if there are tokens yet in the stream that are 
greater then minGramSize.

> NGramTokenFilter creates bad TokenStream
> ----------------------------------------
>
>                 Key: LUCENE-1224
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1224
>             Project: Lucene - Java
>          Issue Type: Bug
>          Components: contrib/*
>            Reporter: Hiroaki Kawai
>            Assignee: Grant Ingersoll
>            Priority: Critical
>         Attachments: LUCENE-1224.patch, NGramTokenFilter.patch, 
> NGramTokenFilter.patch
>
>
> With current trunk NGramTokenFilter(min=2,max=4) , I index "abcdef" string 
> into an index, but I can't query it with "abc". If I query with "ab", I can 
> get a hit result.
> The reason is that the NGramTokenFilter generates badly ordered TokenStream. 
> Query is based on the Token order in the TokenStream, that how stemming or 
> phrase should be anlayzed is based on the order (Token.positionIncrement).
> With current filter, query string "abc" is tokenized to : ab bc abc 
> meaning "query a string that has ab bc abc in this order".
> Expected filter will generate : ab abc(positionIncrement=0) bc
> meaning "query a string that has (ab|abc) bc in this order"
> I'd like to submit a patch for this issue. :-)

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