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From: Mathieu Lecarme <mathieu@garambrogne.net>
Subject: Re: Several questions about scoring/sorting + random sorting in an
 image/related application
Date: Fri, 15 Jun 2007 22:14:03 +0200
To: java-user@lucene.apache.org

Walt explain differently what I said.
Lucene can be efficiently use for selecting objects, without sorting =20
or scoring anything, then, with id stored in Lucene, you can sort =20
yourself with a simple Sortable implementation.
The only limit is that lucene gives you not too much results, with =20
your 300 maximal responses, you can play with it easily.

M.
Le 15 juin 07 =E0 19:07, Walt Stoneburner a =E9crit :

> Antoine Baudoux writes:
>> I want to be able to give a score to each collection.
>
> Keep in mind, Lucene is computing a score based on quite a number of
> things from how often a term is used in a document, how often it
> appears in the collection of documents, how long the query is, etc.
>
> If your concept of a document's score changes, then I'd be inclined to
> think you're possibly using Lucene in a manner it wasn't designed for.
> That said, I have two thoughts.
>
> THOUGHT ONE
> Use Lucene to locate "records" for you --- what you really are
> interested in getting back _from Lucene_ is the primary key.  Then,
> use this key to do a lookup in your database of the score of the day
> and sort accordingly.  The idea is that Lucene finds, your table
> scores, and because of that you won't need to re-index when something
> changes.
>
> THOUGHT TWO
> Use boosting.  COLLECTION_ONE^5  COLLECTION_THREE^10  etc.  That way
> /if/ the Lucene document appears in the collection, it's score is
> weighted according to your preferences.  You're free to change the
> boosts on a query-by-query basis without having to re-index.
>
>
>> I can use a Very big ... query ... I am afraid that it will be slow.
> Try it.  I think you'll find Lucene is _fast_.  We do some pretty HUGE
> and complicated queries and Lucene just screams.
>
>
>> I can add another field to each document, containing a computed
>> custom score, then i could sort on that field. But i want to avoid
>> this solution at all costs, since it would mean re-indexing all the
>> documents each time the collection scores change.
> Or, use indirection - instead of keeping the score, keep the primary
> key of a score table.  Then in a database, where speed won't be the
> issue, perform the look up.   Honestly, if you're only got 300
> categories, you could keep that simple table in memory using less
> space than a small text file.
>
>
>
>> I would also like to implement random-sorting. ... Is it a good =20
>> solution?
>> Is there another way to do it?
>
> This really, really, really feels like you're force fitting Lucene to
> do some business logic piece of a larger application.  May I be so
> bold as to ask what's the _actual_ problem you're trying to solve.
> ("I'm trying to make a hole in a piece of oak" as opposed to "What's
> the best way to sharpen a Phillips screwdriver enough to cut wood?")
>
> Keep in mind that the forum is for Lucene, so parts of your questions
> may be answered outside of the forum.
>
> -wls
>
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