[jira] [Updated] (LUCENE-3426) optimizer for n-gram PhraseQuery

["Koji Sekiguchi (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/LUCENE-3426?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Koji Sekiguchi updated LUCENE-3426:
-----------------------------------

    Attachment: LUCENE-3426.patch

First draft. The patch doesn't include test yet.

I added optimizeForNgram() methods in the patch that will remove "redundant" terms and positions.

Optimizing PhraseQuery will change score.

> optimizer for n-gram PhraseQuery
> --------------------------------
>
>                 Key: LUCENE-3426
>                 URL: https://issues.apache.org/jira/browse/LUCENE-3426
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: core/search
>            Reporter: Koji Sekiguchi
>            Priority: Trivial
>         Attachments: LUCENE-3426.patch
>
>
> If 2-gram is used and the length of query string is 4, for example q="ABCD", QueryParser generates (when autoGeneratePhraseQueries is true) PhraseQuery("AB BC CD") with slop 0. But it can be optimized PhraseQuery("AB CD") with appropriate positions.
> The idea came from the Japanese paper "N.M-gram: Implementation of Inverted Index Using N-gram with Hash Values" by Mikio Hirabayashi, et al. (The main theme of the paper is different from the idea that I'm using here, though)

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