From: Andres Freund <andres@anarazel.de>
To: Greg Stark <gsstark@mit.edu>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@postgresql.org, pgsql-performance@postgresql.org, Michael Clemmons <glassresistor@gmail.com>
Cc: Hannu Krosing <hannu@2ndquadrant.com>
Cc: Scott Marlowe <scott.marlowe@gmail.com>
Subject: Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)
Date: Wed, 03 Feb 2010 13:03:04 +0100
Message-ID: <4B6965F8.7040106@anarazel.de> (raw)
In-Reply-To: <407d949e1002030353g522f1afev782a97fd755c5926@mail.gmail.com>
References: <4427a97a0912101235x3ade510blcc00d5ce9883c6b6@mail.gmail.com>
<23321.1265133015@sss.pgh.pa.us>
<603c8f071002021014h4b489f44s9014377e1b38dbc7@mail.gmail.com>
<201002021934.18444.andres@anarazel.de>
<603c8f071002021106o5eef7b40r1ed21c9bd05251ec@mail.gmail.com>
<29129.1265139210@sss.pgh.pa.us>
<603c8f071002021145x1939c9e7hb2eedc8ae4dfe23e@mail.gmail.com>
<407d949e1002030353g522f1afev782a97fd755c5926@mail.gmail.com>
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
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To: pgsql-hackers@postgresql.org
Cc: andres@anarazel.de, gsstark@mit.edu, robertmhaas@gmail.com, tgl@sss.pgh.pa.us, glassresistor@gmail.com, hannu@2ndquadrant.com, scott.marlowe@gmail.com
Subject: Re: [HACKERS] Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)
In-Reply-To: <4B6965F8.7040106@anarazel.de>
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