FAQ
Hi Eric,
I don't see how sorting relates to your problem at all....
Could you just explain how is sorting different from boosting?

I have been trying to figure this out. Going through "Lucene In Action" my
understanding of sorting is that it will kind of second level of ordering
after the query results have been scored (Not sure if the relevance established
by scoring is lost in this process).

Is it *really* better for your users to see a low-relevance query
that happens to have the exact words in it before a very-high
ranking but not quite exact response?
Nopes. Thats the last thing my product manager will want.

Lets take an example to simplify this:

I have fields like title, description, tags. Now when I search for a term
"Indoor Photography" then I would like the results with exact match in title to be
more important than in description or tags. However, if there is an exact match in description
then it should be given more preference than the partial match in title.

Going by the points mentioned below and as per one of your posts
(http://mail-archives.apache.org/mod_mbox/lucene-java-user/200609.mbox/%3CPine.LNX.4.58.0609271134380.32280@hal.rescomp.berkeley.edu%3E)
I understand that I need to specify query time boosting like this:

title:Indoor Photography^2.5 description:Indoor Photography^1.5 tags:
Indoor Photography^1.2

Let me know if this would help my cause.

Thnx for ur time n the valuable info.

--Rakesh S




Date: Fri, 21 Dec 2007 09:53:02 -0500
From: erickerickson@gmail.com
To: java-user@lucene.apache.org
Subject: Re: Boosting Vs Sorting

OK, I'm trying to adjust to a Mac and my keyboard shortcuts sometimes
lead me to send the mail when I didn't intend. Sorry about that...

So, leaving aside how you form your "similar" query, I *think* you
want to form two clauses, your "exact" and your "similar" and
boost them individually, combined in a boolean query.

This will still interleave the results I think. But it's also a valid
question whether this is good or bad. Is it *really* better for your
users to see a low-relevance query that happens to have the exact
words in it before a very-high ranking but not quite exact response?
That, of course it up to your product manager....

If it is really a requirement, it seems to me that you would be able to
just form the two queries independently, then just post-process them.
One query is the exact version, and the second query is the similar one.
Then just combine the results as you please by iterating the hits
object for the exact query then following it by the same for the similar.

I don't see how sorting relates to your problem at all....

Best
Erick
On Dec 21, 2007 9:46 AM, Erick Erickson wrote:

From my perspective, index-time boosting and sorting are apples
and oranges.

According to a post from Hoss, index-time boosting is a way of
saying that "Field x in this document is more important than
field x in other documents". Query-time boosts are a way of
saying "I care about field X more than field Y across *all*
documents".

So index time boosting doesn't seem to relate to your problem since
you really want to compare field x across all documents. It seems
that query-time boosting is more relevant.

So, leaving aside how you form your "similar" q

On Dec 20, 2007 10:50 PM, Rakesh Shete wrote:


Hi all,

I am using Hibernate Search (http://www.hibernate.org/410.html) which is
a wrapper around Lucene for performing search over info stored in the DB. I
have questions related to Lucene boosting Vs sorting:

Is index time boosting of documents and fields better than specifying
sorting parameters at search time?

I have been browsing through the Lucene mail archives for an answer to
this. Going through them and reading on stuff related to Lucene scoring, my
understanding is that if I know upfront at index time that the relevance
order of results is based on certain fields, then, it is better to have
index time boosting of documents and fields. Am I right here?

My requirements are like:
Results having an exact match to the input query string should have
highest preference followed by an exact match with field1, field2, field3
and then followed by search query substring (or near match) match with
field1, field2, field3.

Any suggestions are most welcome.

--Rakesh S

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postedDec 21, '07 at 3:51a
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