Re: Visibility map and freezing

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От
Simon Riggs
Тема
Re: Visibility map and freezing
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Msg-id
1232484037.2327.227.camel@ebony.2ndQuadrant
Ответ на
Re: Visibility map and freezing (Heikki Linnakangas)
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Дерево обсуждения
Visibility map and freezing Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Re: Visibility map and freezing Zdenek Kotala <Zdenek.Kotala@Sun.COM>
Re: Visibility map and freezing Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Re: Visibility map and freezing Gregory Stark <greg.stark@enterprisedb.com>
Re: Visibility map and freezing Peter Eisentraut <peter_e@gmx.net>
Re: Visibility map and freezing Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Re: Visibility map and freezing Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Re: Visibility map and freezing Jeff Davis <pgsql@j-davis.com>
Re: Visibility map and freezing Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Re: Visibility map and freezing Jeff Davis <pgsql@j-davis.com>
Re: Visibility map and freezing Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Re: Visibility map and freezing Jeff Davis <pgsql@j-davis.com>
Re: Visibility map and freezing Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Re: Visibility map and freezing Alvaro Herrera <alvherre@commandprompt.com>
Re: Visibility map and freezing Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Re: Visibility map and freezing Gregory Stark <stark@enterprisedb.com>
Re: Visibility map and freezing ITAGAKI Takahiro <itagaki.takahiro@oss.ntt.co.jp>
Re: Visibility map and freezing Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Re: Visibility map and freezing Simon Riggs <simon@2ndQuadrant.com>
Re: Visibility map and freezing Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Re: Visibility map and freezing Simon Riggs <simon@2ndQuadrant.com>
Re: Visibility map and freezing Euler Taveira de Oliveira <euler@timbira.com>
Re: Visibility map and freezing Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Re: Visibility map and freezing Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Re: Visibility map and freezing "Fujii Masao" <masao.fujii@gmail.com> 

On Tue, 2009-01-20 at 21:51 +0200, Heikki Linnakangas wrote:

> Attached is a simple patch to only start skipping pages after 20 
> consecutive pages marked as visible in the visibility map. This doesn't 
> do any "look-ahead", so it will always scan the first 20 pages of a 
> table before it starts to skip pages, and whenever there's even one page 
> that needs vacuuming, the next 19 pages will also be vacuumed.
> 
> We could adjust that figure 20 according to table size. Or by 
> seq_page_cost/random_page_cost. But I'm leaning towards a simple 
> hard-coded value for now.

Yes, sounds good. Can we stick to multiples of 2 as the OS readahead
does IIRC? So either 16 or 32. I'd go 32.

-- Simon Riggs           www.2ndQuadrant.comPostgreSQL Training, Services and Support
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