Re: CBO - hash join vs nested loops

  • From: "Radoulov, Dimitre" <cichomitiko@xxxxxxxxx>
  • To: "Christian Antognini" <Christian.Antognini@xxxxxxxxxxxx>
  • Date: Fri, 2 Dec 2005 17:44:42 +0100

Checked the CDN and NDV for the tables/columns and they seem OK, but I have to check the indexes stats too.
The only think I noticed is that the CBO expects 2076 rows before the final distinct and they are 1401.


I thought it could be something more "obvious" and "easy" :O).



Thanks,
Dimitre Radoulov




----- Original Message ----- From: "Christian Antognini" <Christian.Antognini@xxxxxxxxxxxx>
To: <cichomitiko@xxxxxxxxx>
Cc: <oracle-l@xxxxxxxxxxxxx>
Sent: Friday, December 02, 2005 4:32 PM
Subject: RE: CBO - hash join vs nested loops



Dimitre

Subject: CBO - hash join vs nested loops

Did you compare the estimated cardinalities with the real one? If not, it's the right place to start... In fact with 3 conditions it's quite easy to mislead the CBO.



HTH
Chris


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