| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Florian Weimer <fweimer(at)bfk(dot)de> |
| Cc: | David Fetter <david(at)fetter(dot)org>, PG Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Page Checksums + Double Writes |
| Date: | 2011-12-22 08:55:29 |
| Message-ID: | CA+U5nMK96DzttA0z=PaL8jy+4bi2_6nMFzQyTOJdfW244FmQ-g@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Dec 22, 2011 at 8:42 AM, Florian Weimer <fweimer(at)bfk(dot)de> wrote:
> * David Fetter:
>
>> The issue is that double writes needs a checksum to work by itself,
>> and page checksums more broadly work better when there are double
>> writes, obviating the need to have full_page_writes on.
>
> How desirable is it to disable full_page_writes? Doesn't it cut down
> recovery time significantly because it avoids read-modify-write cycles
> with a cold cache?
It's way too late in the cycle to suggest removing full page writes or
code them. We're looking to add protection, not swap out existing
ones.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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