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Date: Wed, 03 Feb 2010 13:03:04 +0100
From: Andres Freund <andres@anarazel.de>
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To: Greg Stark <gsstark@mit.edu>
CC: Robert Haas <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>,
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Subject: Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1
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On 02/03/10 12:53, Greg Stark wrote:
> On Tue, Feb 2, 2010 at 7:45 PM, Robert Haas<robertmhaas@gmail.com>  wrote:
>> I think you're probably right, but it's not clear what the new name
>> should be until we have a comment explaining what the function is
>> responsible for.
>
> So I wrote some comments but wasn't going to repost the patch with the
> unchanged name without explanation... But I think you're right though
> I was looking at it the other way around. I want to have an API for a
> two-stage sync and of course if I do that I'll comment it to explain
> that clearly.
>
> The gist of the comments was that the function is preparing to fsync
> to initiate the i/o early and allow the later fsync to fast -- but
> also at the same time have the beneficial side-effect of avoiding
> cache poisoning. It's not clear that the two are necessarily linked
> though. Perhaps we need two separate apis, though it'll be hard to
> keep them separate on all platforms.
I vote for two seperate apis - sure, there will be some unfortunate 
overlap for most unixoid platforms but its sure better possibly to allow 
adding more platforms later at a centralized place than having to 
analyze every place where the api is used.

Andres