CODEWITHSUNDEEP
ruby-on-railssolrsunspot
zivaricha
zivaricha

Reputation: 248

Sunspot Solr fulltext search-time score boost

I am using Solr search-engine in our Ruby On Rails app. using the sunspot gem for the implementation.

I have a couple of questions regarding the fulltext boosting mechanisem. Im trying to boost certain results up the result set if they meet certain condition, So lets say:

# Posts with pizza, scored higher if featured
Post.search do
  fulltext 'pizza' do
     boost(2.0) { with(:featured, true) }
  end
end

i would expect all the Posts that contain 'pizza' and are featured = true, will get a score of 2.0 and all the rest to not get scored at all OR get a score of 0.

What actually happens is that all Posts with featured=true, get a score number which i cant predict (ie. 5.089861) regardless of the 2.0 i set in the search block.

Even if i increase the boosting number to 20.0 or 50.0, or if i add another boost if the Post matched another condition, the actual scores are still in the 5.XXX zone...

Moreover, Posts that are are featured=false, also have a score, of 0.09928045(ish) which i would expect to be an absolute 0.

Can anyone further explain how the scoring mechanism work, specifically:

  1. How can i control the actual score value (since 2.0 doesnt really give a score value of 2)
  2. Why objects that don't meet the scoring condition, still gets a score (though lower)

Thanks.

Upvotes: 0

Views: 351

Answers (1)

Samuel-Zacharie Faure
Samuel-Zacharie Faure

Reputation: 1152

Scoring doesn't work that way. Sunspot is literally boosting the score, it is not setting the score to the exact value. This is also why non-boosted fields returns a lower value.

This page describe how scoring (and boosting) works on the Lucene level.

Since this is not the way Sunspot / Solr / Lucene is intended to work, I doubt that there is a setting to allow you to fix the score, actually I can't think of a use case where you'd need to do this.

But if you really want to it should be fairly easy to implement your own solution :

  • For returning only values which satisfy a certain field condition, you should use sunspot-solr faceting.
  • Then you can patch the result to give it whatever score you want.

Upvotes: 2

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