Re: straight join on columns with frequency histograms

Igor,

Check my website for addenda to the book, Alberto is the person who worked out several of the formula that I didn't manage to figure out for my book.

Regards

Jonathan Lewis
http://www.oracle.com/technology/community/oracle_ace/ace1.html#lewis

The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html

Cost Based Oracle: Fundamentals
http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html

• Original Message ----- From: "Igor Neyman" <ineyman_at_perceptron.com> To: <alberto.dellera_at_gmail.com>; "oracle-l" <oracle-l_at_freelists.org> Sent: Friday, October 06, 2006 5:42 PM Subject: RE: straight join on columns with frequency histograms

Did you check J.Lewis "Cost-Based Oracle Fundamentals"?

-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Alberto Dell'Era Sent: Friday, October 06, 2006 12:29 PM
To: oracle-l
Subject: straight join on columns with frequency histograms

Dear List,

I'm currently investigating, for a complex issue I have but also "just for fun", the CBO formula used for the estimation of the cardinality of

select ...
  from t1, t2
 where t1.x = t2.x;

where both t1.x and t2.x have *frequency* histograms associated.

Has anyone already investigated something similar, and likes to share the results with me ?

I have already discovered "most" of the formula, that looks simple and intuitive, minus some "border" cases that I'm currently investigating - but I would like to avoid reinventing the wheel if someone has already discovered the full formula.

Thanks in advance
Alberto

--

Alberto Dell'Era
"Per aspera ad astra"

--

http://www.freelists.org/webpage/oracle-l Received on Fri Oct 06 2006 - 11:58:47 CDT