If you want a 'global' IDF across different fields, maybe one solution is to use a copyfield to copy all the fields in a common field (e.g, title, authors, body, footer all copied into a copyfield call text), and then you should be able to use it with a function query or by implementing your own similarity score, retrieving the idf on the defined copyfield...
Cheers, Diego From: solr-user@lucene.apache.org At: 03/20/19 16:26:08To: solr-user@lucene.apache.org Subject: BM25F in Solr Hi There have been several discussions in the past on how to do BM25F scoring in Solr. People have mentioned BlendedTermQuery and in Lucene 8.0 we got a new BM25FQuery. What I mainly want is to normalize the doc freq (IDF) across fields, so that e.g. title field uses same doc-freq as body field. And ideally it should work in any query parser, including edismax. Have any of you succeeded in this, alternatively some other workaround achieving a normalized IDF across fields? An approximation could be to always use doc-freq from the largest field in the index, e.g. body, but not sure if you can do that in Similarity? -- Jan Høydahl, search solution architect Cominvent AS - www.cominvent.com
