From: | Aidan Van Dyk <aidan(at)highrise(dot)ca> |
---|---|
To: | Greg Stark <gsstark(at)mit(dot)edu> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Gurjeet Singh <singh(dot)gurjeet(at)gmail(dot)com>, PGSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Protecting against unexpected zero-pages: proposal |
Date: | 2010-11-09 14:28:36 |
Message-ID: | AANLkTikuuLMFL0gv9XL7=jfxHQ8CYRfgXC_UoLC9N-KA@mail.gmail.com |
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Lists: | pgsql-hackers |
On Tue, Nov 9, 2010 at 8:45 AM, Greg Stark <gsstark(at)mit(dot)edu> wrote:
> But buffering the page only means you've got some consistent view of
> the page. It doesn't mean the checksum will actually match the data in
> the page that gets written out. So when you read it back in the
> checksum may be invalid.
I was assuming that if the code went through the trouble to buffer the
shared page to get a "stable, non-changing" copy to use for
checksumming/writing it, it would write() the buffered copy it just
made, not the original in shared memory... I'm not sure how that
write could be in-consistent.
a.
--
Aidan Van Dyk Create like a god,
aidan(at)highrise(dot)ca command like a king,
http://www.highrise.ca/ work like a slave.
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