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RE: In an Analyze Necessary?

From: <Rajesh.Rao_at_jpmchase.com>
Date: Mon, 06 May 2002 07:53:32 -0800
Message-ID: <F001.00458DC2.20020506075332@fatcity.com>

John,

>> You seem to be one of those lucky DBAs who don't have performance issues :)

This is just one of the 150 databases. A DBA needs performance issues, backup failures, disk failures, 600 errors, dropped tables, et all, to justify wages above the minimum wages law ;-)

Raj

                                                                                                                     
                    John Kanagaraj                                                                                   
                    <john.kanagara        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>        
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                    May 03, 2002                                                                                     
                    06:23 PM                                                                                         
                    Please respond                                                                                   
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Rajesh,

You seem to be one of those lucky DBAs who don't have performance issues :) Just keep in mind that when statistics are NOT present and the CBO is forced
by one of the many reasons, some defaults will be assumed. These defaults are absolutely invalid and incorrect. So, even if you analyze once, these stats will remain and provide the CBO with a picture which is more or less correct (unless your data is really skewed).

Rather than completely switch off stats collection, why don't you look at what's the difference between that stats between one weekend's ANALYZE and the next? If the changes are not significant, then you may choose to perform
this only once a quarter or so....

One of the myths with Stats collection is 'Analyze everyday!', but the truth
is 'it all depends'.

John Kanagaraj
Oracle Applications DBA
DBSoft Inc
(W): 408-970-7002

The manuals for Oracle are here: http://tahiti.oracle.com The manual for Life is here: http://www.gospelcom.net ** The opinions and statements above are entirely my own and not those of my
employer or clients **

> But, me thinks, I will go ahead and disable that once a week
> analyze cron
> job. The CPU can be better utilized for the other night batch jobs.

> > A datawarehouse. There are only a few selected SQL's run
> against this
> > database. And all this SQL's are tuned to optimum during design with
> hints
> > embedded to take the least execution time. The SQL's
> currently execute
> in
> > times, much better than what the expected response time was
> by the users.
> > Would it still be required to analyze the tables? What
> other benefits
> would
> > one reap from an analyze? Assume that there are no other
> SQL's running
> > against the database other than this select few, and the data in the
> > underlying tables has been accounted for a period of 2 years during
> design.
> > Any new SQL's which would need to be added would go thru the drawing
> board.
> > Absolutely Nothing adhoc.

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Author: John Kanagaraj
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-- 
Author: 
  INET: Rajesh.Rao_at_jpmchase.com

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Received on Mon May 06 2002 - 10:53:32 CDT

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