RE: Tuning By cardinality Estimates

  • From: "Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx>
  • To: "hrishys@xxxxxxxxxxx" <hrishys@xxxxxxxxxxx>, "breitliw@xxxxxxxxxxxxx" <breitliw@xxxxxxxxxxxxx>, "Desai, Bhavik (MLITS)" <Bhavik_Desai@xxxxxx>, "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
  • Date: Fri, 6 Mar 2009 09:02:35 -0700

A common example of correlated join criteria would be:

select . . .
where make='FORD'
and model='MUSTANG';

The CBO doesn't know that all Mustangs are built by Ford, so it's not aware 
that the extra filter condition won't really filter out any more rows.


-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On 
Behalf Of hrishy

I didnt quite understand the statement
"Check if the join criteria between SC and SH are correlated"

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