Thanks for clarifying - that you are referring to the bq parameter which is in fact additive to the underlying score within the original query, while in the main query, or using the bf and boost and qf and pf parameters the boosting is multiplicative rather than "additive".
IOW, only in the bq parameter do you need to use negative boost values - in all the other contexts a fractional boost is sufficient. It's unfortunate that the ref guide isn't more clear about this key distinction. Now hopefully we (and others!) are on the same page. -- Jack Krupansky On Sun, Feb 28, 2016 at 3:26 PM, Emir Arnautovic < emir.arnauto...@sematext.com> wrote: > Hi Jack, > I think we are talking about different things: I agree that boost is > multiplicative, and boost values less than zero will reduce score, but if > you use such boost value in bq, it will still bust documents that are > matching it. Simplest example is with ids. If you query: > q=id:a OR id:b > both doc a and b will have same score. If you boost a^2 it will be first, > if you boost a^0.1 it will be second. But if you use dismax's bq=id:a^0.1 > it will be first. In such case you have to use negative boost to make sure > it is last. > > Are we on the same page now? > > Regards, > Emir > > > On 26.02.2016 16:00, Jack Krupansky wrote: > >> Could you share your actual numbers and test case? IOW, the document score >> without ^0.01 and with ^0.01. >> >> Again, to repeat, the specific boost factor may be positive, but the >> effect >> of a fractional boost is to reduce, not add, to the score, so that a score >> of 0.5 boosted by 0.1 would become 0.05. IOW, it de-boosts occurrences of >> the term. >> >> The point remains that you do not need a "negative boost" to de-boost a >> term. >> >> >> -- Jack Krupansky >> >> On Fri, Feb 26, 2016 at 4:01 AM, Emir Arnautovic < >> emir.arnauto...@sematext.com> wrote: >> >> Hi Jack, >>> I just checked on 5.5 and 0.1 is positive boost. >>> >>> Regards, >>> Emir >>> >>> >>> On 26.02.2016 01:11, Jack Krupansky wrote: >>> >>> 0.1 is a fractional boost - all intra-query boosts are multiplicative, >>>> not >>>> additive, so term^0.1 reduces the term by 90%. >>>> >>>> -- Jack Krupansky >>>> >>>> On Wed, Feb 24, 2016 at 11:29 AM, shamik <sham...@gmail.com> wrote: >>>> >>>> Binoy, 0.1 is still a positive boost. With title getting the highest >>>> >>>>> weight, >>>>> this won't make any difference. I've tried this as well. >>>>> >>>>> >>>>> >>>>> -- >>>>> View this message in context: >>>>> >>>>> >>>>> http://lucene.472066.n3.nabble.com/Query-time-de-boost-tp4259309p4259552.html >>>>> Sent from the Solr - User mailing list archive at Nabble.com. >>>>> >>>>> >>>>> -- >>> Monitoring * Alerting * Anomaly Detection * Centralized Log Management >>> Solr & Elasticsearch Support * http://sematext.com/ >>> >>> >>> > -- > Monitoring * Alerting * Anomaly Detection * Centralized Log Management > Solr & Elasticsearch Support * http://sematext.com/ > >
