[jira] [Updated] (LUCENE-6590) Explore different ways to apply boosts

["Adrien Grand (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/LUCENE-6590?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Adrien Grand updated LUCENE-6590:
---------------------------------
    Attachment: LUCENE-6590.patch

I started playing with this idea and here is a first step (only lucene/core and would deserve better docs but tests are passing) if someone would like to have a look. Clone, setBoost and getBoost are removed from the Query API in favour of a new BoostQuery, and query boosts are propagated through Query.createWeight. Next step is to figure out if we can remove this queryBoost parameter from createWeight (to get back to today's trunk signature) and handle everything through Weight.normalize like Robert suggested.

> Explore different ways to apply boosts
> --------------------------------------
>
>                 Key: LUCENE-6590
>                 URL: https://issues.apache.org/jira/browse/LUCENE-6590
>             Project: Lucene - Core
>          Issue Type: Wish
>            Reporter: Adrien Grand
>            Priority: Minor
>         Attachments: LUCENE-6590.patch
>
>
> Follow-up from LUCENE-6570: the fact that all queries are mutable in order to allow for applying a boost raises issues since it makes queries bad cache keys since their hashcode can change anytime. We could just document that queries should never be modified after they have gone through IndexSearcher but it would be even better if the API made queries impossible to mutate at all.
> I think there are two main options:
>  - either replace "void setBoost(boost)" with something like "Query withBoost(boost)" which would return a clone that has a different boost
>  - or move boost handling outside of Query, for instance we could have a (immutable) query impl that would be dedicated to applying boosts, that queries that need to change boosts at rewrite time (such as BooleanQuery) would use as a wrapper.
> The latter idea is from Robert and I like it a lot given how often I either introduced or found a bug which was due to the boost parameter being ignored. Maybe there are other options, but I think this is worth exploring.



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