Well, in a small step in our defense, it DOES state at the top of the
note:
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and in an even larger step, the author of the document
has been asked to review and correct it.
Pete
"Controlling
developers is like herding cats."
Kevin
Loney, Oracle DBA Handbook
"Oh
no, it's not. It's much harder than
that!"
Bruce
Pihlamae, long-term Oracle DBA
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED]
Sent: Saturday, October 18, 2003 5:35 AM
To: Multiple recipients of list ORACLE-L
Subject: Re: re Rebuilding Indexes in Oracle Apps -- was RE: RE:
The article states that leaf blocks are not reused, which is indeed incorrect,
and has been for a very long time.
Hemant K Chitale <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED]10/17/2003 11:42 AM
Please respond to ORACLE-L
To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
cc:
Subject: Re: re Rebuilding Indexes in Oracle Apps -- was RE: RE:
I wonder if "it is not necessary to rebuild indexes" is also a myth.
It IS in some cases necessary
1. Indexes on monotonically increasing values [eg Conrurrent_Request_ID
based on a Sequence
or even on date columns which signify when the record is created] if the
table is also
purged by the same columns frequently
2. Because the disk space used by an Index can be inordinately larged
after a couple of years
and index fast_full_scans are impacted
Have you administered an Oracle Applications database ?
hemant
At 03:29 AM 17-10-03 -0800, you wrote:
>Hi Hemant,
>
>One word perfectly describes the Metalink article you highlighted:
>
>Crap ;)
>
>A nice example of how Oracle Corp is the greatest myth generator of them
>all !! It's all rather sad and embarressing isn't.
>
>Thanks for the headsup. Anyone in a position to get the note removed ?
>
>Cheers
>
>Richard
>
> >Quoting Metalink Note 182699.1 bde_rebuild.sql Validates and Rebuilds
>Fragmentated Indexes (8.0->9.0)
> >
> >Index fragmentation occurs when a key value changes, and the index row is
> >deleted from one place (Leaf Block) and inserted into another.
> >
> > Deleted Leaf Rows are not reused. Therefore indexes whose columns are
> >subject to value change must be rebuilt periodically since they become
>naturally fragmentated.
> >
> >An index is considered to be 'fragmentated' when more than 20% of its Leaf
>Rows space is
> >empty because of the implicit deletes caused by indexed columns value
>changes.
> >
> >Fragmentated indexes degrade the performance of index range scan
>operations.
>
>
>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.net
>--
>Author: Richard Foote
> INET: [EMAIL PROTECTED]
>
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Hemant K Chitale
Oracle 9i Database Administrator Certified Professional
My personal web site is : http://hkchital.tripod.com
--
Please see the official ORACLE-L FAQ: http://www.orafaq.net
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Author: Hemant K Chitale
INET: [EMAIL PROTECTED]
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