Re: [HACKERS] sorting big tables :(

Marc G. Fournier <scrappy@hub.org>

From: The Hermit Hacker <scrappy@hub.org>
To: Tom <tom@sdf.com>
Cc: Bruce Momjian <maillist@candle.pha.pa.us>, mimo@interdata.com.pl, hackers@freebsd.org, hackers@postgreSQL.org
Date: 1998-05-20T17:17:34Z
Lists: pgsql-hackers
On Wed, 20 May 1998, Tom wrote:

> 
> On Wed, 20 May 1998, The Hermit Hacker wrote:
> 
> > 	One of the things that the Unix FS does is auto-defragmenting, at
> > least the UFS one does.  Whenever the system is idle (from my
> > understanding), the kernel uses that time to clean up the file systems, to
> > reduce the file system fragmentation.
> 
>   No, that doesn't happen.  The only way to eliminate fragmentation is a
> dump/newfs/restore cycle.  UFS does do fragmentation avoidance (which is
> reason UFS filesystems have a 10% reserve).

	Okay, then we have two different understandings of this.  My
understanding was that the 10% reserve gave the OS a 'temp area' in which
to move blocks to/from so that it could defrag on the fly...

	Am CC'ng this into freebsd-hackers@freebsd.org for a "third
opinion"...am willing to admit I'm wrong *grin*