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https://issues.apache.org/jira/browse/SOLR-5831?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13933339#comment-13933339
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Peter Keegan commented on SOLR-5831:
------------------------------------
Here is a comparison of ScaleScorePostFilter and a Configurable Collector that
does the same score scaling with the function 'hard wired' in the collector. I
had to hand merge some of the patch from SOLR-4465 into the 4.6.1 branch. My
tests show that the Collector is faster:
1. SolrMeter test @ 20 QPS:
Custom Collector with maxscalehits=10000:
Median response time: 25 ms
Ave response time: 135 ms
Load average: 2.3
PostFilter with maxscalehits=10000:
Median response time: 30 ms
Ave response time: 190 ms
Load average: 3.3
2. Typical response times as a function of hit count:
# hits Collector PostFilter
------ --------- ----------
80K 12 35
230K 20 80
330K 25 123
720K 35 275
1.1M 32 390
These difference in the response times is likely due to the hits being
collected twice by the PostFilter
(once by the PostFilter and once by the delegate collector), but the Custom
Collector only collects the
hits once.
> Scale score PostFilter
> ----------------------
>
> Key: SOLR-5831
> URL: https://issues.apache.org/jira/browse/SOLR-5831
> Project: Solr
> Issue Type: Improvement
> Components: search
> Affects Versions: 4.7
> Reporter: Peter Keegan
> Priority: Minor
> Attachments: SOLR-5831.patch
>
>
> The ScaleScoreQParserPlugin is a PostFilter that performs score scaling.
> This is an alternative to using a function query wrapping a scale() wrapping
> a query(). For example:
> select?qq={!edismax v='news' qf='title^2
> body'}&scaledQ=scale(product(query($qq),1),0,1)&q={!func}sum(product(0.75,$scaledQ),product(0.25,field(myfield)))&fq={!query
> v=$qq}
> The problem with this query is that it has to scale every hit. Usually, only
> the returned hits need to be scaled,
> but there may be use cases where the number of hits to be scaled is greater
> than the returned hit count,
> but less than or equal to the total hit count.
> Sample syntax:
> fq={!scalescore+l=0.0 u=1.0 maxscalehits=10000
> func=sum(product(sscore(),0.75),product(field(myfield),0.25))}
> l=0.0 u=1.0 //Scale scores to values between 0-1, inclusive
> maxscalehits=10000 //The maximum number of result scores to scale (-1 =
> all hits, 0 = results 'page' size)
> func=... //Apply the composite function to each hit. The
> scaled score value is accessed by the 'score()' value source
> All parameters are optional. The defaults are:
> l=0.0 u=1.0
> maxscalehits=0 (result window size)
> func=(null)
>
> Note: this patch is not complete, as it contains no test cases and may not
> conform
> to all the guidelines in http://wiki.apache.org/solr/HowToContribute.
>
> I would appreciate any feedback on the usability and implementation.
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