RE: hinting and the rule based optimizer

  • From: "Goulet, Dick" <DGoulet@xxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Thu, 1 Apr 2004 15:54:16 -0500

Best hint of all, DON'T.

Dick Goulet
Senior Oracle DBA
Oracle Certified 8i DBA

-----Original Message-----
From: ryan.gaffuri@xxxxxxx [mailto:ryan.gaffuri@xxxxxxx]
Sent: Thursday, April 01, 2004 3:04 PM
To: oracle-l@xxxxxxxxxxxxx
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.=20

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