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Home -> Community -> Mailing Lists -> Oracle-L -> Re: Rule Based Optimizer
Dick
I personally think the CBO is a great optimizer even if the first versions 7.0.x,7.1.x, and 7.2 was a bit shaky When somebody say that the CBO has to get better/mature then they typically have worked with the RBO and forgot that humans has this fantastic skill of adapting to known behaviour. That is we unconscious worked as preprocessors to the RBO, by using small tricks like rearranging the from clause, adding a empty sting to the left side of a join, rearranging the order of the predicates in the where clause. Since the CBO is able to take into account so many new things (hash, direct read for sort, parallel ...) when creating a plan for a statement and most of the time do et descent job. When the CBO really F...up a simple plan for at statement we humans get annoyed and surprised over how stupid the CBO is. My experience is that if you take a 1000 Sql statement the and feed them through the CBO and the RBO (with out preprocessing) the CBO will always win or you take a 1000 Sql statement and preprocess then for the RBO and preprocess then via hints and statistics for the CBO the CBO will win :-)
That my to cent's
d, Dick wrote:
Same here. Hopefully 10i's CBO has matured.
Dick Goulet
Senior Oracle DBA
Oracle Certified 8i DBA
-----Original Message-----
Sent: Wednesday, June 11, 2003 1:16 PM
To: Multiple recipients of list ORACLE-L
I know that the CBO existed on Oracle 7.0.15 for HP-UX. I remember it well
because we would frequently get incorrect and inconsistent results.
Installing the 7.0.16 patch _mostly_ fixed these issues.
We still had a large number of queries that we hinted to use the RBO as we
couldn't get the desired query performance with the CBO
Kevin
-----Original Message-----
Sent: Wednesday, June 11, 2003 12:55 PM
To: Multiple recipients of list ORACLE-L
Not true. IIRC the first Oracle version with dual optimizer mode
was 7.1.x.
Best Regards,
K Gopalakrishnan
-----Original Message-----
Mercadante, Thomas F
Sent: Wednesday, June 11, 2003 9:30 AM
To: Multiple recipients of list ORACLE-L
CBO was what I learned on in late version of 5.x and 6.0. It was what
Oracle taught developers back then - with the chart showing the precedence
of how indexes were selected for a spcific query. And how the order of the
tables in the FROM clause was *very* important in telling the CBO how to
operate. Of course, that was when the developers had to know everything
about the data within all the tables to get things to work right.
Tom Mercadante
Oracle Certified Professional
-----Original Message-----
Sent: Wednesday, June 11, 2003 11:50 AM
To: Multiple recipients of list ORACLE-L
I remember CBO in 7.1.6 on AIX...
RF
-----Original Message-----
To: Multiple recipients of list ORACLE-L
Sent: 6/10/2003 6:45 PM
I first saw the CBO in 1994 if IIRC.
Seems to me it was introduced in 7.2.
I'm sure Mogens knows for sure. :)
Jared
"Ryan" <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED]
06/10/2003 04:19 PM
Please respond to ORACLE-L
To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
cc:
Subject: Re: Rule Based Optimizer
there not really quitting cold turkey.... its been phased out. wasnt the
CBO
introduced in 1997? Or was it earlier than that.
----- Original Message -----
To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]>
Sent: Tuesday, June 10, 2003 6:44 PM
RWB, I'll tell you, if KG says it about Oracle, I pretty much would go to
the
bank with it.
RF
-----Original Message-----
To: Multiple recipients of list ORACLE-L
Sent: 6/10/2003 4:24 PM
Mr. Gopalakrishnan:
How do you know this? Can anyone confirm (or deny) this? I hope it is
true!
Oracle should just quit cold turkey and not support the RULE optimizer
at
all in any future releases.
RWB
Reginald W. Bailey
IBM Global Services - ETS SW GDSD - Database Management
Your Friendly Neighborhood DBA
713-216-7703 (Office) 281-798-5474 (Mobile) 713-415-5410 (Pager)
[EMAIL PROTECTED]
.com To: [EMAIL PROTECTED]
Sent by: cc:
[EMAIL PROTECTED] Subject: RE: Rule Based
Optimizer
ity.com
06/10/2003
12:59 PM
Please respond
to ORACLE-L
RULE optimizer will not be supported in next version.
But you can still use the RULE optimizer and it is
just a matter of official support from Oracle.
Best Regards,
K Gopalakrishnan
-----Original Message-----
Goulet, Dick
Sent: Tuesday, June 10, 2003 10:16 AM
To: Multiple recipients of list ORACLE-L
There appears to be a number of folks on the list who have some
insight
into
the next version of the database. I'd like to ask those folks a
simple
question. What is the future of the Rule Based Optimizer looking
like?
Does it die in 10i??
Dick Goulet
Senior Oracle DBA
Oracle Certified 8i DBA
-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Goulet, Dick INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting servicesReceived on Wed Jun 11 2003 - 14:54:07 CDT
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