Re: Index-only scan performance regression

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Index-only scan performance regression
Date: 2012-01-31 19:49:52
Message-ID: CA+Tgmobvyn28tNzEWfToAFavWU17=dR+mtoSgkspFmfWMBvJow@mail.gmail.com
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On Tue, Jan 31, 2012 at 2:15 PM, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com> wrote:
> In the case when we're asked to clear a bit, it would first try to pin
> the relevant page, which would go through vm_readbuf() with extend set
> to true. Then vm_extend() would notice that the visibility map had
> already been extended, and it would read in the new page with the set
> bit. So this case would continue to work, wouldn't it?

Ah, maybe. I haven't tried to code it up. Do you want to take a crack at it?

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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