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Message-ID: <48F36EB8.2030805@deri.org>
Date: Mon, 13 Oct 2008 16:52:24 +0100
From: Renaud Delbru <renaud.delbru@deri.org>
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To: java-user@lucene.apache.org
Subject: Re: Sorting posting lists before intersection
References: <48D10726.4010504@getopt.org> <48F3597B.9080302@deri.org>
 <48F36276.9020603@getopt.org> <200810131721.06919.paul.elschot@xs4all.nl>
In-Reply-To: <200810131721.06919.paul.elschot@xs4all.nl>
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Hi,

Paul Elschot wrote:
> This could be done, but since not all scorers will be TermScorers it
> will be necessary to add a method to Scorer (or perhaps even to its
> DocIdSetIterator superclass):
>
>    public abstract int estimatedDocFreq();
>
> and implement this for all existing instances. TermScorer could
> implement it without estimating.
> For AND/OR/NOT such an estimation is straightforward but for
> proximity queries it would be more of a guess.
>   
I agree. Indeed, for proximity queries, it is more tricky. Maybe taking 
the frequency of the rarest term in a PhraseQuery / SpanQuery could be a 
not so bad predictor in general.

Regards.
-- 
Renaud Delbru

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