Horton

Re: [PATCHES] Full page writes improvement, code update

Richard Huxton <dev@archonet.com>

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From: Richard Huxton <dev@archonet.com>
To: Simon Riggs <simon@2ndquadrant.com>
Cc: Zeugswetter Andreas ADI SD <ZeugswetterA@spardat.at>, Koichi Suzuki <suzuki.koichi@oss.ntt.co.jp>, josh@agliodbs.com, pgsql-hackers@postgresql.org, pgsql-patches@postgresql.org
Date: 2007-03-30T11:48:47Z
Lists: pgsql-hackers 
Simon Riggs wrote:
> On Fri, 2007-03-30 at 11:27 +0100, Richard Huxton wrote:
> 
>> Is that always true? Could the backup not pick up a partially-written 
>> page? Assuming it's being written to as the backup is in progress. (We 
>> are talking about when disk blocks are smaller than PG blocks here, so 
>> can't guarantee an atomic write for a PG block?)
> 
> Any page written during a backup has a backup block that would not be
> removable by Koichi's tool, so yes, you'd still be safe.
> 
> i.e. between pg_start_backup() and pg_stop_backup() we always use full
> page writes, even if you are running in full_page_writes=off mode.

Ah, that's OK then.

-- 
   Richard Huxton
   Archonet Ltd