Thanks Ahmet! The second I read that part about the "albino elephant" query I remembered that I had read that before, but just forgotten about it. That explanation is really good, and really should be part of the regular documentation if you ask me. :)
/Jimi -----Original Message----- From: Ahmet Arslan [mailto:iori...@yahoo.com.INVALID] Sent: Wednesday, April 20, 2016 8:23 PM To: solr-user@lucene.apache.org Subject: Re: Questions about tie parameter for dismax/edismax Hi Jimi, Field based scoring, where you query multiple fields (title,body,keywords etc) with multiple query terms, is an unsolved problem. (E)dismax is a heuristic approach to attack the problem. Please see the javadoc of DisjunctionMaxQuery : https://lucene.apache.org/core/6_0_0/core/org/apache/lucene/search/DisjunctionMaxQuery.html some folks try to obtain optimum parameters of edismax from training data. Others employ learning to rank techniques ... Ahmet On Wednesday, April 20, 2016 6:18 PM, "jimi.hulleg...@svensktnaringsliv.se" <jimi.hulleg...@svensktnaringsliv.se> wrote: Hi, I have been looking a bit at the tie parameter, and I think I understand how it works, but I still have a few questions about it. 1. It is not documented anywhere (as far as I have seen) what the default value is. Some testing indicates that the default value is 0, and it makes perfect sense. But shouldn't that fact be documented? 2. There is very little information about how to think when choosing a tie value. Is there really no general recommendations based on some different use cases? Or is it simple a matter of "try different values and see what happens"? 3. Some recommendations I have seen mention a really low value is the best option. But can someone explain why? I understand that one moves further away from the dismax "philosophy" the higher the tie value one uses. But I care only about the quality of the score calculation. Can someone explain why the score has a higher quality with a lower tie? 4. Regarding the dismax "philosophy". On the dismax wiki page it says: "Max means that if your word 'foo' matches both title and body, the max score of these two (probably title match) is added to the score, not the sum of the two as a simple OR query would do. This gives more control over your ranking." But it doesn't explain *why* this gives "more control over your ranking". Can someone explain the logic behind that statement? I'm not claiming that it is incorrect, I just want to understand it. :) Regards /Jimi
