RE: Oracle 9i hints that are obsolete in 11gR2
From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Mon, 31 Mar 2014 07:54:14 +0000
Message-ID: <CE70217733273F49A8A162EE074F64D901DE6A95_at_exmbx05.thus.corp>
From: oracle-l-bounce_at_freelists.org [oracle-l-bounce_at_freelists.org] on behalf of John Hurley [hurleyjohnb_at_yahoo.com] Sent: 30 March 2014 20:10
To: xt.and.r_at_gmail.com; kibeha_at_gmail.com Cc: big.dave.roberts_at_googlemail.com; ORACLE-L Subject: Re: Oracle 9i hints that are obsolete in 11gR2
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):
- for the CBO to optimize a statement it needs to read the definitions and stats from the data dictionary
- to read the data dictionary you need to be able to execute some recursive SQL
- 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.
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
_at_jloracle
From: oracle-l-bounce_at_freelists.org [oracle-l-bounce_at_freelists.org] on behalf of John Hurley [hurleyjohnb_at_yahoo.com] Sent: 30 March 2014 20:10
To: xt.and.r_at_gmail.com; kibeha_at_gmail.com Cc: big.dave.roberts_at_googlemail.com; ORACLE-L Subject: Re: Oracle 9i hints that are obsolete in 11gR2
Yes "not supported" does not mean yet removed totally ... yet ...
Maria Colgan https://blogs.oracle.com/optimizer/entry/why_was_the_rule_hint
-- http://www.freelists.org/webpage/oracle-lReceived on Mon Mar 31 2014 - 09:54:14 CEST