Re: re Rebuilding Indexes in Oracle Apps -- was RE: RE:

sold out na lahat-yung Tower 3 sa Eastwood is only for Lease??

At 11:34 AM 10/17/2003 -0800, you wrote:

>The article states that leaf blocks are not reused, which is indeed
>incorrect,
>and has been for a very long time.
>
>
>
>Hemant K Chitale <hkchital_at_singnet.com.sg>
>Sent by: ml-errors_at_fatcity.com
>
> 10/17/2003 11:42 AM
> Please respond to ORACLE-L
>
> To: Multiple recipients of list ORACLE-L
> <ORACLE-L_at_fatcity.com>
> 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: richard.foote_at_bigpond.com
> >
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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: hkchital_at_singnet.com.sg
>
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