Re: Number 1 gripe about CBO: 0 <Cardinality< 1 (?????)

On Apr 5, 8:09 pm, "joel garry" <joel-ga..._at_home.com> wrote:
> On Apr 4, 5:16 pm, "Kevin Kirkpatrick" <kvnkrkpt..._at_gmail.com> wrote:
>
>
>
> > > - have no join clause between kk_small and kk_big, yet you list them
> > > in this order, which is obeyed by CBO.
>
> > Did I just step into the twighlight zone? Syband, this comment makes
> > so little sense that I'm literally stumped as to how to reply. Do you
> > know even know what the CBO is?
>
> > > What else do you expect?
>
> > Certainly not a response from a "Senior Oracle DBA" who thinks that
> > the CBO chooses join order based on the order in which tables are
> > listed in a query...
>
> In the case of tie-breakers, that is, where the optimizer thinks the
> cost is equal for two join orders, RBO worked from last to first, CBO
> works in order written, IIRC.
>
> jg
> --
> @home.com is bogus.http://www.speakeasy.org/~jwilton/oracle/oracle-misconceptions.html

There is some evidence that the order in which the tables are listed could be important to the CBO if there are many tables in the SQL statement:
http://jonathanlewis.wordpress.com/2006/11/03/table-order/ http://jonathanlewis.wordpress.com/2006/12/04/thinking-it-through/

Charles Hooper
PC Support Specialist
K&M Machine-Fabricating, Inc. Received on Thu Apr 05 2007 - 20:28:35 CDT