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From Chris Hostetter <hossman_luc...@fucit.org>
Subject Re: Sorting and Empty (non-existing) Fields
Date Wed, 19 May 2010 21:19:29 GMT

: Now I want to search something on the first field and want the results 
: sorted by relevance, then by the first field, then by the second field.

first off: if your primary sort is on relevancy, there are going to be 
very few cases where your secondary sort comes into play -- the scoring 
formula generates a float, and those floats aren't likely to be identical 
unless the documents themselves are extremely similar.

: My problem now is that, if I have a lot of Entries with the same value 
: in the first field and no value in the second field, these entries with 
: no value on the 2nd field are coming first.
: 
: Is there any way to increase the score on those documents which have a 
: value on the second field? Or is there any way to skip those Documents 
: which don't have the second field? I don't want to use a Filter, it 

yes, add a prohibited clause to your query, which is a nested BooleanQuery 
containing a mandatory MatchAllDocsQuery and a prohibited full range query 
on field2 (ie:  "-(+*:* -field2:[* TO *]"  ) ... that will ensure those 
docs are exlcuded from your query.  alternately you could make them score 
lower by just adding an optional clause that boosts the score of any 
docs that do have a value in that field (ie:  "field2[* TO *]^1000"  )

Lastly: if you don't want to affect the scores in any way, and you don't 
wnat to exclude the docs from the result set, just make them sort after 
other docs that do have a value in that field, you can consider using 
something like this...

http://svn.apache.org/viewvc/lucene/dev/trunk/solr/src/java/org/apache/solr/search/MissingStringLastComparatorSource.java

...but note that it only works for sorting "Strings" because that's the 
only type of FieldCache that understands the idea of Documents that are 
"missing" a field.


-Hoss


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