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Home -> Community -> Mailing Lists -> Oracle-L -> RE: MTS&Cost based Optimzer
In this case it will use cost based optimizer anyway (one table with statistics enough), but exection plan can be very bad.
Alex Hillman
-----Original Message-----
Sent: Tuesday, April 24, 2001 12:45 PM
To: Multiple recipients of list ORACLE-L
definitely all or nothing -- if you have analyzed the large table and join it to an unanalyzed small table, you are going to get rule based
>From: "Tim Sawmiller" <sawmillert_at_state.mi.us>
>Reply-To: ORACLE-L_at_fatcity.com
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>Subject: RE: MTS&Cost based Optimzer
>Date: Tue, 24 Apr 2001 07:51:18 -0800
>
>I wouldn't... analyze all or nothing...
>
> >>> deepender.gupta_at_wipro.com 04/24/01 09:46AM >>>
>How would you decide that out of total big and small tables (say 1500)
>these
>are the tables need to be analysed and these are not, as in our case
>Transaction types are both OLTP and DSS ??
>
>
>-----Original Message-----
>Carmichael
>Sent: Tuesday, April 24, 2001 6:46 PM
>To: Multiple recipients of list ORACLE-L
>
>
>
>turning on cost-based is easy: set the optimizer_mode parameter to choose
>in your init.ora, stop and start your database and then analyze all your
>tables.
>
>HOWEVER (and this is a biggie) this will not automatically make all your
>queries run faster. You will need to examine each and every query to see if
>it needs to be rewritten to take advantage of CBO. In fact, sometimes there
>are queries that run faster in rule-based, and I have had to include hints
>in queries to force the optimizer to run rule.
>
> >From: Venkat_Kalepalli <Venkat_Kalepalli_at_satyam.com>
> >Reply-To: ORACLE-L_at_fatcity.com
> >To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> >Subject: MTS&Cost based Optimzer
> >Date: Tue, 24 Apr 2001 02:25:25 -0800
> >
> > > Hello folks!
> > >
> > > I am working in SUN solaris 5.6 with Oracle 8i. I want to implement
>MTS
> > > on the Oracle server. Next we are running with Rule based optimizer
>and
> > > we want to change to costbased optimizer.
> > >
> > > I want to know what are the advantages we get on this and what are the
> > > steps to implement this?
> > >
> > > Any help is grateful...
> > >
> > > Rgd
> > > Venkat
> > > DBA.
> > >
> > >
> > >
>
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>Author: Rachel Carmichael
> INET: carmichr_at_hotmail.com
>
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>Author: Deepender Kr Gupta
> INET: deepender.gupta_at_wipro.com
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>Author: Tim Sawmiller
> INET: sawmillert_at_state.mi.us
>
>Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>San Diego, California -- Public Internet access / Mailing Lists
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Rachel Carmichael INET: carmichr_at_hotmail.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Hillman, Alex INET: Alex.Hillman_at_usmint.treas.gov Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Tue Apr 24 2001 - 14:54:42 CDT
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