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Re: Read/Write block sizes

From: PFC <lists(at)boutiquenumerique(dot)com>
To: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>,"Jeffrey W(dot) Baker" <jwbaker(at)acm(dot)org>
Cc: "Guy Thornley" <guy(at)esphion(dot)com>,"Josh Berkus" <josh(at)agliodbs(dot)com>, pgsql-performance(at)postgresql(dot)org,"Steve Poe" <spoe(at)sfnet(dot)cc>, "Chris Browne" <cbbrowne(at)acm(dot)org>
Subject: Re: Read/Write block sizes
Date: 2005-08-24 10:35:08
Message-ID: op.sv0c0u1cth1vuj@localhost (view raw or flat)
Thread:
Lists: pgsql-performance
> of effort reinventing the wheel ... but our time will be repaid much
> more if we work at levels that the OS cannot have knowledge of, such as
> join planning and data statistics.

	Considering a global budget of man-hours which is the best ?

1- Spend it on reimplementing half of VFS in postgres, half of Windows in  
postgres, half of FreeBSD in postgres, half of Solaris in Postgres, only  
to discover you gain a meagre speed increase and a million and a half bugs,

2- Spending 5% of that time lowering the impedance between the OS and  
Postgres, and another 5% annoying Kernel people and helping them tweaking  
stuff for database use, and the rest on useful features that give useful  
speedups, like bitmap indexes, skip scans, and other features that enhance  
power and usability ?

If you're Oracle and have almost unlimited resources, maybe. But even  
Microsoft opted for option 2 : they implemented ReadFileGather and  
WriteFileScatter to lower the syscall overhead and that's it.

And point 2 will benefit to many other apps, wether 1 would benefit only  
postgres, and then only in certain cases.

I do believe there is something ineresting to uncover with reiser4 though  
(it definitely fits point 2).

I'm happy that the pg team chose point 2 and that new versions keep coming  
with new features at an unbelievable rate these times. Do you guys sleep ?

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