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From jian chen <chenjian1...@gmail.com>
Subject Re: Fwd: skipInterval
Date Sun, 16 Oct 2005 21:16:22 GMT
Hi, Paul,

Thanks for your email. I am not sure how the sqrt vs. constant for
skipInterval will pan out for two or multiple required terms. That needs
some experiments I guess.

Cheers,

Jian

On 10/16/05, Paul Elschot <paul.elschot@xs4all.nl> wrote:
>
> Jian,


> ---------- Forwarded message ----------
> > From: jian chen <chenjian1227@gmail.com>
> > Date: Oct 15, 2005 6:36 PM
> > Subject: skipInterval
> > To: Lucene Developers List <lucene-dev@jakarta.apache.org>
> >
> > Hi, All,
> >
> > I was reading some research papers regarding quick inverted index
> lookups.
> > The classical approach to skipping dictates that a skip should be
> positioned
> > every sqrt(df) document pointers.
>
> The typical use of skipping info in Lucene is in ConjunctionScorer, for a
> query with two required terms. There it helps for the case when one
> term occurs much less frequently than another.
> Iirc the sqrt() is optimal for a single lookup in a single level index,
> reducing the complexity from linear to logarithmic.
> Does the sqrt() also apply in the case of searching for two required terms
> and returning all the documents in which they both occur?
>
> Regards,
> Paul Elschot
>
>
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