RE: converting to the cost based optimizer

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.

>>> hamcdc_at_yahoo.co.uk 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 <VIVEK_SHARMA_at_infosys.com> 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 <smcclure_at_usscript.com> a écrit :
  > >
  > 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
  > >
  

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