It's hard to google on _val_
So, I've been experimenting to learn how the _val_ participates in scores. It seems to me that http://wiki.apache.org/solr/FunctionQuery should explain the *effect* of including an _val_ term in an ordinary query, starting with a constant. http://wiki.apache.org/solr/SolrRelevancyFAQ#How_can_I_change_the_score_of_a_document_based_on_the_.2Avalue.2A_of_a_field_.28say.2C_.22popularity.22.29 poses exactly my question, but does not explain the math. It just says, 'they get a boost'. I tried some experiments. Positive values of _val_ did lead to positive increments in the score, but clearly not by simple addition. Presumably, the brains of the operation are http://lucene.apache.org/core/old_versioned_docs/versions/3_5_0/scoring.html. However, it seems to me that it would be kind to us dumb animals if the Solr pages gave a 'for idiots' summary of the net effect. Left to my own devices, I'll eventually work my way through this, but if someone hands me a shortcut, I'll cheerfully play tech writer here and there.
Re: It's hard to google on _val_
On Sun, Apr 15, 2012 at 11:34 AM, Benson Margulies bimargul...@gmail.com wrote: So, I've been experimenting to learn how the _val_ participates in scores. It seems to me that http://wiki.apache.org/solr/FunctionQuery should explain the *effect* of including an _val_ term in an ordinary query, starting with a constant. It's simply added to the score as any other clause in a boolean query would be. Positive values of _val_ did lead to positive increments in the score, but clearly not by simple addition. That's just because Lucene normalizes scores. By default, this is really just multiplying scores by a magic constant (that by default is the inverse of the sum of squared weights) and doesn't change relative orderings of docs. If you add debugQuery=true and look at the scoring explanations, you'll see that queryNorm component. If you want to go down the rabbit hole on trunk, see IndexSearcher.createNormalizedWeight() -Yonik lucenerevolution.com - Lucene/Solr Open Source Search Conference. Boston May 7-10
Re: It's hard to google on _val_
On Sun, Apr 15, 2012 at 12:14 PM, Yonik Seeley yo...@lucidimagination.com wrote: On Sun, Apr 15, 2012 at 11:34 AM, Benson Margulies bimargul...@gmail.com wrote: So, I've been experimenting to learn how the _val_ participates in scores. It seems to me that http://wiki.apache.org/solr/FunctionQuery should explain the *effect* of including an _val_ term in an ordinary query, starting with a constant. It's simply added to the score as any other clause in a boolean query would be. Positive values of _val_ did lead to positive increments in the score, but clearly not by simple addition. That's just because Lucene normalizes scores. By default, this is really just multiplying scores by a magic constant (that by default is the inverse of the sum of squared weights) and doesn't change relative orderings of docs. If you add debugQuery=true and look at the scoring explanations, you'll see that queryNorm component. If you want to go down the rabbit hole on trunk, see IndexSearcher.createNormalizedWeight() I think I should be able to add some text to the wiki that would help fellow Alice's merely by looking at the debugQuery result. Thanks. -Yonik lucenerevolution.com - Lucene/Solr Open Source Search Conference. Boston May 7-10
Re: It's hard to google on _val_
On Sun, Apr 15, 2012 at 12:14 PM, Yonik Seeley
yo...@lucidimagination.com wrote:
That's just because Lucene normalizes scores. By default, this is
really just multiplying scores by a magic constant (that by default is
the inverse of the sum of squared weights)
Sorry... I missed the square root. Should be inverse of the square
root of the sum of squared weights.
See DefaultSimilarity.queryNorm:
public float queryNorm(float sumOfSquaredWeights) {
return (float)(1.0 / Math.sqrt(sumOfSquaredWeights));
}
-Yonik
lucenerevolution.com - Lucene/Solr Open Source Search Conference.
Boston May 7-10
