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Re: Anything to be gained from a 'Postgres Filesystem'?

From: Aaron Werman <aaron(dot)werman(at)gmail(dot)com>
To: "Leeuw van der, Tim" <tim(dot)leeuwvander(at)nl(dot)unisys(dot)com>
Cc: "Steinar H(dot) Gunderson" <sgunderson(at)bigfoot(dot)com>,pgsql-performance(at)postgresql(dot)org
Subject: Re: Anything to be gained from a 'Postgres Filesystem'?
Date: 2004-10-21 11:47:14
Message-ID: 157f6484041021044720eb7520@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
The intuitive thing would be to put pg into a file system. 

/Aaron

On Thu, 21 Oct 2004 12:44:10 +0200, Leeuw van der, Tim
<tim(dot)leeuwvander(at)nl(dot)unisys(dot)com> wrote:
> Hi,
> 
> I guess the difference is in 'severe hacking inside PG' vs. 'some unknown amount of hacking that doesn't touch PG code'.
> 
> Hacking PG internally to handle raw devices will meet with strong resistance from large portions of the development team. I don't expect (m)any core devs of PG will be excited about rewriting the entire I/O architecture of PG and duplicating large amounts of OS type of code inside the application, just to try to attain an unknown performance benefit.
> 
> PG doesn't use one big file, as some databases do, but many small files. Now PG would need to be able to do file-management, if you put the PG database on a raw disk partition! That's icky stuff, and you'll find much resistance against putting such code inside PG.
> So why not try to have the external FS know a bit about PG and it's directory-layout, and it's IO requirements? Then such type of code can at least be maintained outside the application, and will not be as much of a burden to the rest of the application.
> 
> (I'm not sure if it's a good idea to create a PG-specific FS in your OS of choice, but it's certainly gonna be easier than getting FS code inside of PG)
> 
> cheers,
> 
> --Tim
> 
> 
> 
> -----Original Message-----
> From: pgsql-performance-owner(at)postgresql(dot)org [mailto:pgsql-performance-owner(at)postgresql(dot)org]On Behalf Of Steinar H. Gunderson
> Sent: Thursday, October 21, 2004 12:27 PM
> To: pgsql-performance(at)postgresql(dot)org
> Subject: Re: [PERFORM] Anything to be gained from a 'Postgres Filesystem'?
> 
> On Thu, Oct 21, 2004 at 08:58:01AM +0100, Matt Clark wrote:
> > I suppose I'm just idly wondering really.  Clearly it's against PG
> > philosophy to build an FS or direct IO management into PG, but now it's so
> > relatively easy to plug filesystems into the main open-source Oses, It
> > struck me that there might be some useful changes to, say, XFS or ext3, that
> > could be made that would help PG out.
> 
> This really sounds like a poor replacement for just making PostgreSQL use raw
> devices to me. (I have no idea why that isn't done already, but presumably it
> isn't all that easy to get right. :-) )
> 
> /* Steinar */
> --
> Homepage: http://www.sesse.net/
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-- 

Regards,
/Aaron

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