[jira] Updated: (LUCENE-1360) A Similarity class which has unique length norms for numTerms <= 10

["Robert Muir (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/LUCENE-1360?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Robert Muir updated LUCENE-1360:
--------------------------------

    Attachment: LUCENE-1360.patch

Lance, here's a patch with the similarity i suggested, for lucene's contrib with a unit test.

Then, i think as i mentioned earlier (also on LUCENE-2236), we should create a Solr
issue to make per-field similarity more declarative and add an example short field type.


> A Similarity class which has unique length norms for numTerms <= 10
> -------------------------------------------------------------------
>
>                 Key: LUCENE-1360
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1360
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Query/Scoring
>            Reporter: Sean Timm
>            Assignee: Otis Gospodnetic
>            Priority: Trivial
>         Attachments: LUCENE-1360.patch, LUCENE-1380 visualization.pdf, ShortFieldNormSimilarity.java
>
>
> A Similarity class which extends DefaultSimilarity and simply overrides lengthNorm.  lengthNorm is implemented as a lookup for numTerms <= 10, else as {{1/sqrt(numTerms)}}. This is to avoid term counts below 11 from having the same lengthNorm after stored as a single byte in the index.
> This is useful if your search is only on short fields such as titles or product descriptions.
> See mailing list discussion: http://www.nabble.com/How-to-boost-the-score-higher-in-case-user-query-matches-entire-field-value-than-just-some-words-within-a-field-td19079221.html

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