Re: SQL statement with hints or without hints

I think you have to be a little careful how you phrase your comment here.

In your list there are some things which FORCE the use of CBO, even if the optimizer_mode is set to RULE; and there are some features which are activated ONLY IF the cost based optimizer is invoked.

Off the top of my head, the following force CBO when they appear in an SQL statement

· Partitioned tables and indexes
· Index-organized tables
· SAMPLE clauses in a SELECT statement
· Parallel tables/indexes

and the following are only recognised and used when the CBO has kicked in

· Reverse key indexes
· Function-based indexes
· Query rewrite (materialized views)
· Progress meter
· Hash joins
· Bitmap indexes and bitmap join indexes
· Star transformations
· Partition Views
· Index skip scans

and on these two I pass:
· Star joins
· Extensible optimizer

Jonathan Lewis
http://www.jlcomp.demon.co.uk

Author of:
Practical Oracle 8i: Building Efficient Databases

Next Seminar - Australia - July/August
http://www.jlcomp.demon.co.uk/seminar.html

Host to The Co-Operative Oracle Users' FAQ http://www.jlcomp.demon.co.uk/faq/ind_faq.html

-----Original Message-----
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com> Date: 12 April 2002 19:46

Raj,

Keep in mind that the CBO will be defaulted whenever the following is present:

· Partitioned tables and indexes
· Index-organized tables
· Reverse key indexes
· Function-based indexes
· SAMPLE clauses in a SELECT statement
· Parallel execution and parallel DML (i.e. presence of DEGREE on
Tables/Indexes)
· Star transformations
· Star joins
· Extensible optimizer
· Query rewrite (materialized views)
· Progress meter
· Hash joins
· Bitmap indexes and bitmap join indexes
· Partition Views
· Index skip scans

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Jonathan Lewis
  INET: jonathan_at_jlcomp.demon.co.uk

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
--------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).