Re: straight join on columns with frequency histograms

  • From: "Vlad Sadilovskiy" <vlovsky@xxxxxxxxx>
  • To: jonathan@xxxxxxxxxxxxxxxxxx
  • Date: Fri, 6 Oct 2006 13:12:32 -0400

Could someone please point to the place where I could find formula fo "like
'string'" predicate selectivity with height balanced histograms are present.
Doesn't look like it is the same as range formula.

Thanks,

- Vlad


On 10/6/06, Jonathan Lewis <jonathan@xxxxxxxxxxxxxxxxxx> wrote: 



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@xxxxxxxxxxxxxx>
To: <alberto.dellera@xxxxxxxxx>; "oracle-l" <oracle-l@xxxxxxxxxxxxx>
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@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"

--
//www.freelists.org/webpage/oracle-l



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