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https://issues.apache.org/jira/browse/LUCENE-5175?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13738818#comment-13738818
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Tom Burton-West commented on LUCENE-5175:
-----------------------------------------
I wondered about that "crazy cache", in that it makes the implementation
dependent on the norms implementation.
BTW: It looks to me with Lucene's default norms that there are only about 130
or so "document lengths". If there is no boosting going on the byte value has
to get to 124 for a doclenth = 1, so there are only 255-124 =131 possible
different lengths.
i=124 norm=1.0,doclen=1.0
> Add parameter to lower-bound TF normalization for BM25 (for long documents)
> ---------------------------------------------------------------------------
>
> Key: LUCENE-5175
> URL: https://issues.apache.org/jira/browse/LUCENE-5175
> Project: Lucene - Core
> Issue Type: Improvement
> Components: core/search
> Reporter: Tom Burton-West
> Priority: Minor
> Attachments: LUCENE-5175.patch
>
>
> In the article "When Documents Are Very Long, BM25 Fails!" a fix for the
> problem is documented. There was a TODO note in BM25Similarity to add this
> fix. I will attach a patch that implements the fix shortly.
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