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"
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http://www.freelists.org/webpage/oracle-l

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http://www.freelists.org/webpage/oracle-l Received on Fri Oct 06 2006 - 11:42:08 CDT