| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | mark(at)mark(dot)mielke(dot)cc |
| Cc: | Simon Riggs <simon(at)2ndquadrant(dot)com>, 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: New CRC algorithm: Slicing by 8 |
| Date: | 2006-10-24 17:51:47 |
| Message-ID: | 20061024175147.GN26593@alvh.no-ip.org |
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| Thread: | |
| Lists: | pgsql-hackers |
mark(at)mark(dot)mielke(dot)cc wrote:
> I'm on wrong on one of these assumptions, I'm open to being educated.
> My opinion as of a few seconds ago, is that a write to a single disk
> sector is safe, but that a write that extends across several sectors
> is not.
Unless it's fsync'ed, which is what we do at CHECKPOINT. Keep in mind
that we save full page images on WAL the first time we touch the page
after a checkpoint. This means that if a partial write occured, we will
restore it from WAL.
So it's not safe in general, but it is safe in Postgres.
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
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