Re: gsoc, text search selectivity and dllist enhancments

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От Alvaro Herrera
Тема Re: gsoc, text search selectivity and dllist enhancments
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Msg-id 20080710202731.GH3757@alvh.no-ip.org
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Ответ на Re: gsoc, text search selectivity and dllist enhancments  (Jan Urbański <j.urbanski@students.mimuw.edu.pl>)
Ответы Re: gsoc, text search selectivity and dllist enhancments  (Jan Urbański <j.urbanski@students.mimuw.edu.pl>)
Re: gsoc, text search selectivity and dllist enhancments  (Tom Lane <tgl@sss.pgh.pa.us>)
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Jan Urbański wrote:

> Oh, one important thing. You need to choose a bucket width for the LC  
> algorithm, that is decide after how many elements will you prune your  
> data structure. I chose to prune after every twenty tsvectors.

Do you prune after X tsvectors regardless of the numbers of lexemes in
them?  I don't think that preserves the algorithm properties; if there's
a bunch of very short tsvectors and then long tsvectors, the pruning
would take place too early for the initial lexemes.  I think you should
count lexemes, not tsvectors.


-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.


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