On 18/02/2013 16:26, Uwe Schindler wrote:
The problem is:
Lucene has never supported *real* per-document boosts. Those boosts were always
per-field. As we only work per-field, it depends on the query how your results
score. If you have a TermQuery, the per-field boost is used (the one from the
field queried), but e.g. if you have another query (like MultiTermQuery) the
boost is ignored completely. As it is always per-field, the results of this
per-document boosting differ depending on the number of terms in your query, so
it is not easy to make it consistent.
To boost a document in Lucene 1.x, 2.x, 3.x, and also 4.x, you have to use a
function query with a per-document value that you have indexed as a separate
(ideally as docvalues) field. In previous Lucene versions, FieldCache was the way
to go. This code is a simple wrapper around your query with CustomScoreQuery and a
ValueSource referring to the DocValues field, 5 lines of code -> and it will
return consistent results!
Uwe
Thanks bit clearer now, but 5 line example would be nice
And if this is the way to do things isnt the migration doc incorrect
Paul
-----
Uwe Schindler
H.-H.-Meier-Allee 63, D-28213 Bremen
http://www.thetaphi.de
eMail: u...@thetaphi.de
-----Original Message-----
From: Paul Taylor [mailto:paul_t...@fastmail.fm]
Sent: Monday, February 18, 2013 5:08 PM
To: Uwe Schindler
Cc: java-user@lucene.apache.org
Subject: Re: What is equivalent to Document.setBoost() from Lucene 3.6
inLucene 4.1 ?
On 18/02/2013 16:04, Uwe Schindler wrote:
It is not a regression, as per-Document boost were never working correctly.
If you want to boost documents in a consistent way (and make their scores in
search results really using that factor), you should index a DocValues field
and use that in a CustomScoreQuery to boost the results with that docvalues
field. In Lucene 4.0 (together with other changes) we dropped the "old-
style", confusing, and incorrect feature.
Well per-Document boost seemed to worked for me with my tests. This new
method your propose sounds more complex and is different to what the
migration guide says so I don't see that as an improvement.
Paul
-----
Uwe Schindler
H.-H.-Meier-Allee 63, D-28213 Bremen
http://www.thetaphi.de
eMail: u...@thetaphi.de
-----Original Message-----
From: Paul Taylor [mailto:paul_t...@fastmail.fm]
Sent: Monday, February 18, 2013 4:54 PM
To: Ian Lea
Cc: java-user@lucene.apache.org
Subject: Re: What is equivalent to Document.setBoost() from Lucene
3.6 inLucene 4.1 ?
On 18/02/2013 13:41, Ian Lea wrote:
See the migration guide:
"If you previously used Document.setBoost, you must now pre-multiply
the document boost into each Field.setBoost. If you have a
multi-valued field, you should do this only for the first Field
instance (ie, subsequent Field instance sharing the same field name
should only include their per-field boost and not the document level
boost) as the boost for multi-valued field instances are multiplied
together by Lucene."
--
Ian.
On Mon, Feb 18, 2013 at 12:17 PM, Paul Taylor
<paul_t...@fastmail.fm>
wrote:
What is equivalent to Document.setBoost() from Lucene 3.6 inLucene
4.1
?
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Thanks, so its more difficult now sounds like a regression to me.
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