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Re: signature method in locate

From: Ondrej Bilka
Subject: Re: signature method in locate
Date: Mon, 11 May 2009 11:42:15 +0200
User-agent: Mutt/1.5.18 (2008-05-17)

On Mon, May 11, 2009 at 10:39:11AM +0200, James Youngman wrote:
> On Mon, May 11, 2009 at 8:14 AM, Ondrej Bilka <address@hidden> wrote:
> > Hello,
> > Was signature method discused here? search gives only pgp.
> > Its that you give to each letter bit create signature.
> > When searching you first create signature from largest continuous part not 
> > containing /. Then you can compare signature of each directory and filename.
> > There is risk it will be slowdown because you need to read more.
> I'm sorry, I did not understand what you were trying to express.
> Would you try again with an example?
Sure. Say you have files aaa ,baba, abcd and aaccee. Signatures are
10000, 11000, 11110 and 10101
If we want find *ba*, it coresponds to 11000 and by comparing signatures we 
know that we can match baba or abcd but not aaa and aaccee.
It has problem that if path is long signature would consist from all 1 and we 
dont get any information. But we can split path to parts separated by slashes 
and do it partwise. If pattern is a?bcd  ? can be / so we seek bcd. 
We know that /ab/bc/cd cant contain pattern because signatures 
11000,01100,00110 dont contain 01110.
Signature would be 4 bytes long by hash widechar%32.
> Thanks,
> James


The cables are not the same length.

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