Hello Chris,
Thank you very much for your reply !
I have neither personally tried 11g now, nor read the 11g documentation till now, but it will come anyway ;)
The multidimentional/hybrid (in Oracle terms "extended statistics") histograms are well known in the academic world, I
was just interested in the Oracle implementation:
http://www.sigmod.org/vldb/conf/1997/P486.PDF
http://citeseer.ist.psu.edu/poosala97selectivity.html
http://citeseer.ist.psu.edu/poosala97selectivity.html
http://portal.acm.org/citation.cfm?id=223841&dl=ACM&coll=GUIDE
http://portal.acm.org/citation.cfm?doid=233269.233342
http://www.cs.cmu.edu/~natassa/courses/15-823/current/papers/poosala96improved.pdf
http://www1.cs.columbia.edu/~gravano/Papers/2004/icde04.pdf
http://citeseer.ist.psu.edu/358037.html

---overview of historams
http://infolab.stanford.edu/~widom/cs346/ioannidis.pdf

I had an imperssion that multidimentional histograms need much more than 254 buckets in order to be
precise enough. Another issue (according the academic research papers) is the maintainance of this histograms...

"
I tested it carefully and it works fine. This is IMHO one of the central features of 11g. Why? Simply because it solves
a real problem occurring in virtually every database. Of course the marketing will never tell us something about that
;-)"

Oracle Marketing is pretty busy advertising the most new, hot features ( SQL Plan Management and Database reply to
mention a few) that should be separately licenced e.g. bring more revenue.

Of course, I will participate at your session in October.

Have a nice weekend.
Best Regards. Milen

-----Original Message-----
From: oracle-l-bounce@(protected)
Sent: Saturday, July 21, 2007 10:29 AM
To: Milen Kulev
Cc: oracle-l@(protected)
Subject: RE: Hybrid histograms in 11g ?


Hi Milen

> Are these so called "Hybrid histograms" ?

No. In the documentation they are called extended statistics. And that because it's not only matter of providing
histogram, but all kind of object statistics

> If yes, is there still a constraint of 254 buckets per histogram?

Yes.

> Any ideas, experiences from "early birds" in this list ?

I tested it carefully and it works fine. This is IMHO one of the central features of 11g. Why? Simply because it solves
a real problem occurring in virtually every database. Of course the marketing will never tell us something about that
;-)


HTH
Chris

PS: During the next TechEvent I'll hold a presentation about the 11g new features related to the query optimizer.
Extended statistics will be part of it... So, feel free to participate ;-)
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