RE: Index scan and redundant sorting

From: Bobak, Mark <Mark.Bobak_at_il.proquest.com>
Date: Wed, 25 Feb 2004 15:16:47 -0500
Message-ID: <4C9B6FDA0B06FE4DAF5918BBF0AD82CF03B452C9@bosmail00.bos.il.pqe>

Yep, you got it.

Mark J. Bobak
Oracle DBA
ProQuest Company
Ann Arbor, MI
"Imagination was given to man to compensate him for what he is not, and a sense of humor was provided to console him for what he is." --Horace Walpole

	-----Original Message-----
	From: Daniel Fink [mailto:Daniel.Fink_at_Sun.COM] 
	Sent: Wednesday, February 25, 2004 3:10 PM
	To: oracle-l_at_freelists.org
	Subject: Re: Index scan and redundant sorting
	
	
	Let's see if I understand correctly. For an IFS or IRS, the

blocks of an index are read (in single block read mode) in the order of their existence within the tree. For an IFFS, all blocks in the segment (below the HWM) are read in order of their 'physical' existence within the segment. This is not the order of their existence within the tree, so the blocks are 'out of order'.

Dan

"Bobak, Mark" wrote:

Dan,Only an INDEX FULL SCAN (walks the tree, does single block reads) provides sorted output.An INDEX FAST FULL SCAN (does not walk tree structure, does multi-block reads, discards branch blocks) does NOT provide sorted output.-Mark

		Mark J. Bobak 
		Oracle DBA 
		ProQuest Company 
		Ann Arbor, MI 
		"Imagination was given to man to compensate him for what

he is not, and a sense of humor was provided to console him for what he is." --Horace Walpole

Please see the official ORACLE-L FAQ: http://www.orafaq.com

To unsubscribe send email to: oracle-l-request_at_freelists.org put 'unsubscribe' in the subject line.
--

Archives are at http://www.freelists.org/archives/oracle-l/ FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html

Received on Wed Feb 25 2004 - 14:13:43 CST