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From "Preetam Rao (JIRA)" <>
Subject [jira] Created: (LUCENE-1853) PhraseQuery Scorer for scoring sub phrase matches
Date Tue, 25 Aug 2009 10:24:59 GMT
PhraseQuery Scorer for scoring sub phrase matches

                 Key: LUCENE-1853
             Project: Lucene - Java
          Issue Type: Improvement
          Components: Search
         Environment: Lucene/Java
            Reporter: Preetam Rao
            Priority: Minor
             Fix For: 2.9

For a query like "homes in new york with swimming pool", if a document's field matches only
"new york" it should get scored and it should get scored higher than two separate matches
"new" and "york".  Also, a 3 word sub phrase match must gets scored considerably higher than
a 2 word sub phrase match. (boost factor should be configurable)

If a user query is taken as is without parsing and is searched against multiple fields, where
each sub-phrase can match against a different field, this kind of query is useful. 

Using shingles for this use case, means each field of each document needs to be indexed as
shingles of all (1..N)-grams as well as the query. (Please correct me if I am wrong.)

The scorer could also support 
- ignoring of idf and/or field norms, (so that factors outside the document don't influence
- consider only the longest match (for example match on "new york" is scored and considered
rather than "new" furniture and "york" city)
- ignore duplicates ("new york" appearing twice or thrice does not make any difference)

This kind of query (Phrase Query with SubPhraseScorer) could be combined with DisMax query.
For example, something like solr's dismax request handler can be made to use this query where
we run a user query as it is against all fields and configure each field with above configurations.

I have also attached a patch with comments and test cases in case, my description is not clear
enough. Would appreciate alternatives or feedback. The goal is to give more control via configuration
when searching using user entered queries against multiple fields where sub phrases have special

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