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Re: suggestions for table/index reorg

From: Jared Still <jkstill_at_gmail.com>
Date: Mon, 1 Aug 2005 18:54:23 +0100
Message-ID: <bf463805080110541cec9d92@mail.gmail.com>


Hi Roger,

SAP consultants and Admins often take it as gospel that tables/indexes and entire tablespaces MUST be reorged on a regular basis to achieve optimum performance.

What you will need to do is explain to them under what circumstances a reorg may actually be a good idea, and that other than those circumstances it is a waste of time.

eg. The COEP table on your system may be out of control and grown to extraordinary size. Once the SAP team is allowed to archive data from this table (remove it) there will be a lot of empty space in this table. (maybe a few hundred gig)

This is an example whereby a table rebuild would be a good idea. Other tables can grow into the space freed up by rebuilding the COEP table.

A tablespace reorg may even be in order if you want to completely free up the space so that Oracle no longer owns the disk space.

Rebuilding a table to improve the clustering factor may be another reason to reorg.

SAP folks have bought into the myth that massive reorgs are a necessary fact of life. I've worked with a BASIS admin in the past who was a strong believer in that. Not fun. No, we didn't reorg. :)

Someone else has already give the URL for Richard Footes powerpoint on index internals. You should probably study it and distill as needed for whomever you need to educate.

HTH Jared

On 7/28/05, Roger Xu <roger_xu_at_dp7uptx.com> wrote:
>
> Oracle 9.2.0.4.0 with DMTS (dictionary-managed tablespace)
> Solaris 9
> Any documents, web links, white papers which can help me to convince my
> management
> that table/index reorg should be avoid for it is unnecessary, even we are
> not using LMTS.
> The reason we cannot use LMTS is: SAP 4.0B does NOT support
> locally-managed tablespace.
> Thanks,
> Roger
>
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-- 
Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist

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Received on Mon Aug 01 2005 - 12:56:30 CDT

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