[jira] [Commented] (LUCENE-3957) Document precision requirements of setBoost calls

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

    [ https://issues.apache.org/jira/browse/LUCENE-3957?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13247185#comment-13247185 ] 

Robert Muir commented on LUCENE-3957:
-------------------------------------

I don't think we should put docs there in those classes:

in trunk you can use however many bytes you want for this,
so the text would be wrong anyway. 

its an implementation detail of the default similarity that 
it uses a single byte, and it documents it does this already.

                
> Document precision requirements of setBoost calls
> -------------------------------------------------
>
>                 Key: LUCENE-3957
>                 URL: https://issues.apache.org/jira/browse/LUCENE-3957
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: general/javadocs
>    Affects Versions: 3.5
>            Reporter: Jordi Salvat i Alabart
>
> The behaviour of index-time boosts seems pretty erratic (e.g. a boost of 8.0 produces the exact same score as a boost of 9.0) until you become aware that these factors end up encoded in a single byte, with a three-bit mantissa. This consumed a whole day of research for us, and I still believe we were lucky to spot it, given how deeply dug into the code & documentation this information is.
> I suggest adding a small note to the JavaDoc of setBoost methods in Document, Fieldable, FieldInvertState, and possibly AbstractField, Field, and NumericField.
> Suggested text:
> "Note that all index-time boost values end up encoded using Similarity.encodeNormValue, with a 3-bit mantissa -- so differences in the boost value of less than 25% may easily be rounded away."

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira

        

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