I never said CBO came up with smarter plans...what I said was that you get a optimizer decision that is very similar to rule-based (which is where the original posted is migrating from) and as a bonus, rather than just choosing "any old index" as the rule based optimizer does, the cbo will hopefully make a smarted choice about which index to use (whilst still leaning toward the NL plans).
I never claimed this was optimal - but what it *does* do is result in a fairly easy way to slowly move from rule-based to cost-based. hth connor --- Binley Lim <[EMAIL PROTECTED]> wrote: > > That parameter does not make CBO comes up with any > smarter plans - just more likely to choose NLJ > whether its better or not. HJ can outperform all > other joins in a lot of cases if you maintain > statistics judiciously, including the appropriate > use of histograms. > > >>> [EMAIL PROTECTED] 11/21/02 12:24a.m. >>> > One quick hack is to set the "optimizer_..." params > to > make indexes look super-wonderful, which then gives > you a rule-based "look and feel" with hopefully a > little smarter selection of indexes as a bonus > > hth > connor > > --- VIVEK_SHARMA <[EMAIL PROTECTED]> wrote: > > > > Consider using OUTLINES for Fixed Execution plans > > especially for Batch Queries > > > > This will prevent a Sudden Increment in Processing > > Time due to Optimizer choosing NON-Optimal paths > > > > > > -----Original Message----- > > Sent: Wednesday, November 20, 2002 3:20 AM > > To: Multiple recipients of list ORACLE-L > > > > > > We will be in the same process soon. > > We'll have to consolidate over 100 instances to > > something between 40-60 instances and switch from > > RBO > > to CBO. > > > > Any tips are welcome. > > > > > > --- Steve McClure <[EMAIL PROTECTED]> a �crit > : > > > > > I am just starting to look at converting to the > cost > > > based optimizer, and am > > > hoping a few of you can share insights from > having > > > done so in the past. Our > > > application is an oltp system developed on > 7.3.4. > > > > > We made liberal use of > > > +0 and other RBO "hints", and I am wondering if > > > these are going to cause us > > > troubles when switching to CBO. > > > > > > We have been on 8i since April of this year, > and > > I > > > am just now starting to > > > gather information on the inner workings of the > > CBO. > > > I know it is where I > > > want to be, I am just looking to see how > > > painful/painless the transition > > > will be. > > > > > > Steve McClure > > > > > > -- > Please see the official ORACLE-L FAQ: > http://www.orafaq.com > -- > Author: Binley Lim > INET: [EMAIL PROTECTED] > > Fat City Network Services -- 858-538-5051 > http://www.fatcity.com > San Diego, California -- Mailing list and web > hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an > E-Mail message > to: [EMAIL PROTECTED] (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). ===== Connor McDonald http://www.oracledba.co.uk http://www.oaktable.net "GIVE a man a fish and he will eat for a day. But TEACH him how to fish, and...he will sit in a boat and drink beer all day" __________________________________________________ Do You Yahoo!? Everything you'll ever need on one web page from News and Sport to Email and Music Charts http://uk.my.yahoo.com -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: =?iso-8859-1?q?Connor=20McDonald?= INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (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).
