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Re: hinting and the rule based optimizer

From: <Juriy.Matey_at_bmo.com>
Date: Thu, 1 Apr 2004 15:36:00 -0500
Message-ID: <OFD3230ED2.18BBBC04-ON85256E69.007112CC-85256E69.00716CA7@notes.bmo.com>


Ryan,
the ONLY hint you can use with RBO is /*+ rule */ Any other hint will force using CBO.

Juriy Matey

<ryan.gaffuri_at_cox.net>
Sent by: oracle-l-bounce_at_freelists.org
04/01/2004 03:03 PM
Please respond to oracle-l  

        To:     oracle-l_at_freelists.org
        cc: 
        Subject:        hinting and the rule based optimizer


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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Received on Thu Apr 01 2004 - 14:47:58 CST

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