[jira] Updated: (LUCENE-1420) Similarity.lengthNorm and positionIncrement=0

["Andrzej Bialecki (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/LUCENE-1420?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andrzej Bialecki  updated LUCENE-1420:
--------------------------------------

    Attachment: similarity.patch

This patch adds Similarity,length(fieldName, numTokens, numOverlapTokens), and provides backward-compatible implementation in Similarity.java.

> Similarity.lengthNorm and positionIncrement=0
> ---------------------------------------------
>
>                 Key: LUCENE-1420
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1420
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Index
>    Affects Versions: 2.3.3, 2.9
>            Reporter: Andrzej Bialecki 
>             Fix For: 2.3.3, 2.9
>
>         Attachments: similarity.patch
>
>
> Calculation of lengthNorm factor should in some cases take into account the number of tokens with positionIncrement=0. This should be made optional, to support two different scenarios:
> * when analyzers insert artificially constructed tokens into TokenStream (e.g. ASCII-fied versions of accented terms, stemmed terms), and it's unlikely that users submit queries containing both versions of tokens: in this case lengthNorm calculation should ignore the tokens with positionIncrement=0.
> * when analyzers insert synonyms, and it's likely that users may submit queries that contain multiple synonymous terms: in this case the lengthNorm should be calculated as it is now, i.e. it should take into account all terms no matter what is their positionIncrement.
> The default should be backward-compatible, i.e. it should count all tokens.
> (See also the discussion here: http://markmail.org/message/vfvmzrzhr6pya22h )

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


---------------------------------------------------------------------
To unsubscribe, e-mail: java-dev-unsubscribe@lucene.apache.org
For additional commands, e-mail: java-dev-help@lucene.apache.org