You need to change your similarity object to be more sensitive at the short end. This is a patch about how to do this:
http://issues.apache.org/jira/browse/LUCENE-2187 It involves Lucene coding. On Fri, Mar 12, 2010 at 3:19 AM, muneeb <muneeba...@hotmail.com> wrote: > > Ah I see. > Thanks very much Jay for your explanation, it really helped a lot. > > I guess I have to deal with this in some other way, since I am working with > short titles and I really want short titles to appear at top. Can you > suggest anything to bring titles with length 3 to appear before titles with > length 4 (given they have similar scores)? > > Thanks, > > > Jay Hill wrote: >> >> The fieldNorm is computed like this: fieldNorm = lengthNorm * >> documentBoost >> * documentFieldBoosts >> >> and the lengthNorm is: lengthNorm = 1/(numTermsInField)**.5 >> [note that the value is encoded as a single byte, so there is some >> precision >> loss] >> >> So the values are not pre-set for the lengthNorm, but for some counts the >> fieldLength value winds up being the same because of the precision los. >> Here >> is a list of lengthNorm values for 1 to 10 term fields: >> >> # of terms lengthNorm >> 1 1.0 >> 2 .625 >> 3 .5 >> 4 .5 >> 5 .4375 >> 6 .375 >> 7 .375 >> 8 .3125 >> 9 .3125 >> 10 .3125 >> >> That's why, in your example, the lengthNorm for 3 and 4 is the same. >> >> -Jay >> http://www.lucidimagination.com >> >> >> >> >> >> On Thu, Mar 11, 2010 at 9:50 AM, muneeb <muneeba...@hotmail.com> wrote: >> >>> >>> >>> : >>> : Did you reindex after setting omitNorms to false? I'm not sure whether >>> or >>> : not it is needed, but it makes sense. >>> >>> Yes i deleted the old index and reindexed it. >>> Just to add another fact, that the titlles length is less than 10. I am >>> not >>> sure if solr has pre-set values for length normalizations, because for >>> titles with 3 as well as 4 terms the fieldNorm is coming up as 0.5 (in >>> the >>> debugQuery section). >>> >>> >>> -- >>> View this message in context: >>> http://old.nabble.com/field-length-normalization-tp27862618p27867025.html >>> Sent from the Solr - User mailing list archive at Nabble.com. >>> >>> >> >> > > -- > View this message in context: > http://old.nabble.com/field-length-normalization-tp27862618p27874123.html > Sent from the Solr - User mailing list archive at Nabble.com. > > -- Lance Norskog goks...@gmail.com
