[hibernate-issues] [Hibernate-JIRA] Commented: (HSEARCH-133) Allow ovrriding DefaultSimilarity for indexing and searching

[ http://opensource.atlassian.com/projects/hibernate/browse/HSEARCH-133?pag... ] John Griffin commented on HSEARCH-133: -------------------------------------- The method of Lucene scoring in the DefaultSimilarity class is: score(q,d) = coord(q,d) - queryNorm(q) - SIGMA ( tf(t in d) - idf(t)2 - t.getBoost() - norm(t,d) ) t in q Use cases: Let's say that I don't care about what the term frequency count (tf) is in a document when it's scored. I only want to know if a certain term appeared at all. I would override the tf(float freq) abstract method to return 1.0. Let's say that I want to increase a document's score by a factor of two if it contains more than one of the terms I am querying by. I would override the coord(int overlap, int maxOverlap) to return (overlap * 2)/maxOverlap. As a final example I want to develop a 'ThresholdSimilarity' to increase the score of a document if and only if it contains more than a certain number of query terms regardless of the repository document count. Below that 'threshold' the scoring calculation remains the same as the default. I would override the idf(int docFreq, int numDocs) method to perform this calculation. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://opensource.atlassian.com/projects/hibernate/secure/Administrators.... - For more information on JIRA, see: http://www.atlassian.com/software/jira