RE: straight join on columns with frequency histograms
- From: "Igor Neyman" <ineyman@xxxxxxxxxxxxxx>
- To: <alberto.dellera@xxxxxxxxx>, "oracle-l" <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 6 Oct 2006 12:42:08 -0400
Did you check J.Lewis "Cost-Based Oracle Fundamentals"?
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] 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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