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https://issues.apache.org/jira/browse/LUCENE-10650?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Adrien Grand resolved LUCENE-10650.
-----------------------------------
Resolution: Won't Fix
> "after_effect": "no" was removed what replaces it?
> --------------------------------------------------
>
> Key: LUCENE-10650
> URL: https://issues.apache.org/jira/browse/LUCENE-10650
> Project: Lucene - Core
> Issue Type: Wish
> Reporter: Nathan Meisels
> Priority: Major
>
> Hi!
> We have been using an old version of elasticsearch with the following
> settings:
>
> {code:java}
> "default": {
> "queryNorm": "1",
> "type": "DFR",
> "basic_model": "in",
> "after_effect": "no",
> "normalization": "no"
> }{code}
>
> I see [here|https://issues.apache.org/jira/browse/LUCENE-8015] that
> "after_effect": "no" was removed.
> In
> [old|https://github.com/apache/lucene-solr/blob/releases/lucene-solr/5.5.0/lucene/core/src/java/org/apache/lucene/search/similarities/BasicModelIn.java#L33]
> version score was:
> {code:java}
> return tfn * (float)(log2((N + 1) / (n + 0.5)));{code}
> In
> [new|https://github.com/apache/lucene-solr/blob/releases/lucene-solr/8.11.2/lucene/core/src/java/org/apache/lucene/search/similarities/BasicModelIn.java#L43]
> version it's:
> {code:java}
> long N = stats.getNumberOfDocuments();
> long n = stats.getDocFreq();
> double A = log2((N + 1) / (n + 0.5));
> // basic model I should return A * tfn
> // which we rewrite to A * (1 + tfn) - A
> // so that it can be combined with the after effect while still guaranteeing
> // that the result is non-decreasing with tfn
> return A * aeTimes1pTfn * (1 - 1 / (1 + tfn));
> {code}
> I tried changing {color:#172b4d}after_effect{color} to "l" but the scoring is
> different than what we are used to. (We depend heavily on the exact scoring).
> Do you have any advice how we can keep the same scoring as before?
> Thanks
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