From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
---|---|
To: | Shane Ambler <pgsql(at)007Marketing(dot)com> |
Cc: | Dawid Kuroczko <qnex42(at)gmail(dot)com>, Andreas Seltenreich <andreas+pg(at)gate450(dot)dyndns(dot)org>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: why not kill -9 postmaster |
Date: | 2006-10-20 15:12:46 |
Message-ID: | 20061020151246.GE6718@alvh.no-ip.org |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-general |
Shane Ambler wrote:
> Dawid Kuroczko wrote:
> >On 10/20/06, Shane Ambler <pgsql(at)007marketing(dot)com> wrote:
>
> >>The one thing worse than kill -9 the postmaster is pulling the power
> >>cord out of the server. Which is what makes UPS's so good.
> >
> >
> >Well, I think that pulling the power cord is much safer than killing -9
> >the postmaster. If you pull the plug, then during bootup postgresql
> >will just replay every COMMITed transaction, so there won't be any
> >dataloss or downtime.
>
> If you kill -9 the postmaster the system can still finish sending
> changes to disk and close the file but pulling the power cord can stop a
> write in the middle of a block giving you half new data and half old
> data in the one file.
That case is protected against in the WAL code. That's what we save
whole page images for.
The only difference between kill -9 postmaster and abrupt shutdown, is
that on the former case there may be backends that continue to run and
commit transactions. Those will still be WAL-logged though.
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
From | Date | Subject | |
---|---|---|---|
Next Message | Martijn van Oosterhout | 2006-10-20 15:19:29 | Re: why not kill -9 postmaster |
Previous Message | John Sidney-Woollett | 2006-10-20 15:09:31 | Upgrade 7.4 to 8.1 or 8.2? |