Basiclly, RBO the Rule based optimizer uses 'rules' to optimize and
create the best way to retrieve data. Cost based optimizer will create
paths depending upon the data, (how much data in a table may determine
whether to use and index for example). For CBO to work the tables
and/or indexes must be 'analyzed' to collect statistics such as how many
rows are in the tables. The stats are kept in data dictionary views
like dba_tables, dba_indexes...

You should analyze your schemas regularly.

RBO is obsolete in 10g, (albeit, I think oracle allows for a work
around, probably undocumented).

So why waste your time with RBO, Oracle support only lasts so many
versions back, and therefore you are going to have to insure your
application works with CBO eventually... so don't put it off.

-----Original Message-----
From: simion
[mailto:oracledba-ezmlmshield-x64542623.[Email address protected]
Sent: Monday, August 01, 2005 4:38 AM
To: LazyDBA Discussion
Subject: Re: OracleTuning Pack-Oracle Expert is it RBO only

What's the difference between RBO and CBO. can anyone give me a detailed
answer.


On Mon, 1 Aug 2005 13:58:05 +0530, Gyanjit Kanungo wrote:
> Can Gurus give some idea about OracleTuning Pack-Oracle Expert . Is
> it RBO (Rule based optimizer) only .
> Can we user it in CBO .
> wating for your answers
> Gynajit
>
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