RE: Oracle 9i hints that are obsolete in 11gR2

From: Jonathan Lewis <>
Date: Mon, 31 Mar 2014 07:54:14 +0000
Message-ID: <CE70217733273F49A8A162EE074F64D901DE6A95_at_exmbx05.thus.corp>

It could be quite hard for Oracle to remove the Rule based optimizer completely - though they might manage to disable it for all application (or non-sys users, perhaps):

  1. for the CBO to optimize a statement it needs to read the definitions and stats from the data dictionary
  2. to read the data dictionary you need to be able to execute some recursive SQL
  3. to execute SQL you first have to optimize it - see step 1

At some point, of course, Oracle Corp. may build in pre-compiled execution plans for all recursive SQL.

Jonathan Lewis

From: [] on behalf of John Hurley [] Sent: 30 March 2014 20:10
To:; Cc:; ORACLE-L Subject: Re: Oracle 9i hints that are obsolete in 11gR2

Yes "not supported" does not mean yet removed totally ... yet ...

Maria Colgan

Received on Mon Mar 31 2014 - 09:54:14 CEST

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