Re: Bug: Buffer cache is not scan resistant

From: Grzegorz Jaskiewicz <gj(at)pointblue(dot)com(dot)pl>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "Luke Lonergan" <llonergan(at)greenplum(dot)com>, "PGSQL Hackers" <pgsql-hackers(at)postgresql(dot)org>, "Doug Rady" <drady(at)greenplum(dot)com>, "Sherry Moore" <sherry(dot)moore(at)sun(dot)com>
Subject: Re: Bug: Buffer cache is not scan resistant
Date: 2007-03-05 08:17:06
Message-ID: 6A435FB4-81CF-49A2-9001-E8D34581CDE3@pointblue.com.pl
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On Mar 5, 2007, at 2:36 AM, Tom Lane wrote:
> n into account.
>
> I'm also less than convinced that it'd be helpful for a big seqscan:
> won't reading a new disk page into memory via DMA cause that memory to
> get flushed from the processor cache anyway?

Nope. DMA is writing directly into main memory. If the area was in
the L2/L1 cache, it will get invalidated. But if it isn't there, it
is okay.

--
Grzegorz Jaskiewicz
gj(at)pointblue(dot)com(dot)pl

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