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https://issues.apache.org/jira/browse/LUCENE-4198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16352218#comment-16352218
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Adrien Grand commented on LUCENE-4198:
--------------------------------------

This change had an impact on the nightly benchmarks:

 - AndHighHigh: -3% 
[http://people.apache.org/~mikemccand/lucenebench/AndHighHigh.html]

 - AndHighMed: -4% 
[http://people.apache.org/~mikemccand/lucenebench/AndHighMed.html]

 - AndHighOrMedMed: -4% 
[http://people.apache.org/~mikemccand/lucenebench/AndHighOrMedMed.html]

 - AndMedOrHighHigh: -5% 
[http://people.apache.org/~mikemccand/lucenebench/AndMedOrHighHigh.html]

 

However indexing speed and term queries seem unaffected. And phrase queries 
only have a very minor slowdown, which might be noise (~1%). I'll look into it 
later, but I think this is an acceptable slowdown given how it allows to speed 
up top-k queries.

> Allow codecs to index term impacts
> ----------------------------------
>
>                 Key: LUCENE-4198
>                 URL: https://issues.apache.org/jira/browse/LUCENE-4198
>             Project: Lucene - Core
>          Issue Type: Sub-task
>          Components: core/index
>            Reporter: Robert Muir
>            Priority: Major
>             Fix For: master (8.0)
>
>         Attachments: LUCENE-4198-BMW.patch, LUCENE-4198.patch, 
> LUCENE-4198.patch, LUCENE-4198.patch, LUCENE-4198.patch, LUCENE-4198.patch, 
> LUCENE-4198_flush.patch, 
> TestSimpleTextPostingsFormat.asf.nightly.master.1466.consoleText.excerpt.txt, 
> TestSimpleTextPostingsFormat.sarowe.jenkins.nightly.master.681.consoleText.excerpt.txt
>
>
> Subtask of LUCENE-4100.
> Thats an example of something similar to impact indexing (though, his 
> implementation currently stores a max for the entire term, the problem is the 
> same).
> We can imagine other similar algorithms too: I think the codec API should be 
> able to support these.
> Currently it really doesnt: Stefan worked around the problem by providing a 
> tool to 'rewrite' your index, he passes the IndexReader and Similarity to it. 
> But it would be better if we fixed the codec API.
> One problem is that the Postings writer needs to have access to the 
> Similarity. Another problem is that it needs access to the term and 
> collection statistics up front, rather than after the fact.
> This might have some cost (hopefully minimal), so I'm thinking to experiment 
> in a branch with these changes and see if we can make it work well.



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