Re: hinting and the rule based optimizer
- From: Connor McDonald <hamcdc@xxxxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Fri, 2 Apr 2004 01:39:44 +0100 (BST)
Maybe you can have your cake and eat it as well?
- Analyze all tables
- Set optimizer_mode to rule in init.ora to keep your app happy
- Use 'choose' hint where you want to use cbo for particular cases (eg adhoc
query, end user
reporting) etc etc
hth
connor
--- ryan.gaffuri@xxxxxxx wrote: > We have a legacy 8.1.7.3 instance that is in
RBO mode. My group
does not own it, so we cannot
> change it to CBO.
>
> When I hint anything from an index to ordered, etc... it switches to the CBO
> and since nothing
> is analyzed, it's an even worse plan... Not allowed to analyze the tables
> either because it's
> not our property.
>
> Any rules around hinting the RBO in 8.1.7.3? Why would it switch to the CBO
> from a simple hint?
> I never use the RBO so please bare with me.
>
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=====
Connor McDonald
Co-author: "Mastering Oracle PL/SQL - Practical Solutions" - available now
web: http://www.oracledba.co.uk
web: http://www.oaktable.net
email: connor_mcdonald@xxxxxxxxx
"GIVE a man a fish and he will eat for a day. But TEACH him how to fish,
and...he will sit in a boat and drink beer all day"
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