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Re: Dead Space Map version 3 (simplified)

From: Hiroki Kataoka <kataoka(at)interwiz(dot)jp>
To: pgsql-patches(at)postgresql(dot)org
Subject: Re: Dead Space Map version 3 (simplified)
Date: 2007-04-23 04:41:21
Message-ID: 462C38F1.6040300@interwiz.jp (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
Heikki Linnakangas wrote:
> The way you update the DSM is quite interesting. When a page is dirtied, 
> the BM_DSM_DIRTY flag is set in the buffer descriptor. The corresponding 
> bit in the DSM is set lazily in FlushBuffer whenever BM_DSM_DIRTY is 
> set. That's a clever way to avoid contention on updates. But does it 
> work for tables that have a small hot part that's updated very 
> frequently?

I think there is no problem.  Bloating will make pages including the 
unnecessary area which will not be accessed.  Soon, those pages will be 
registered into DSM.

Or, though it expands however, do you assume accessing all pages equally?

-- 
Hiroki Kataoka <kataoka(at)interwiz(dot)jp>

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