RE: Index scan and redundant sorting
- From: "Niall Litchfield" <n-litchfield@xxxxxxxxxxxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 25 Feb 2004 23:38:46 +0000
That is my understanding too.
-----Original Message-----
From: AC.GWIA.oracle-l@xxxxxxxxxxxxx [mailto:AC.GWIA.oracle-l@xxxxxxxxxxxxx]
Sent: Wed 25/02/2004 20:10
To: Daniel.Fink@xxxxxxx; oracle-l@xxxxxxxxxxxxx
Cc:
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
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