| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
 |
 | |||
| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
|
| |||
Home -> Community -> Mailing Lists -> Oracle-L -> RE: MTS&Cost based Optimzer
Hi Rachel,
It was my impresssion that joining an analyzed and unanalyzed tables will
used CBO, but the choice of access path will be badly skewed since the
assumptions Oracle makes about the unanalyzed table will probably be nowhere
near reality.
Obviously this can result in a terrible access path.
Jay Miller
-----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.
> > >
> > >
> > >
>
>_________________________________________________________________
>Get your FREE download of MSN Explorer at http://explorer.msn.com
>
>--
>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: Deepender Kr Gupta
> INET: deepender.gupta_at_wipro.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: 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
>--------------------------------------------------------------------
>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: 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: Miller, Jay INET: JayMiller_at_TDWaterhouse.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).Received on Tue Apr 24 2001 - 13:50:07 CDT
 |
 |