In this particular case, you can get the RULE behaviour by putting the NO_UNNEST hint into the subquery. It's what I've actually been doing for some of the tests, and it seems to make no difference. Regards Jonathan Lewis http://www.jlcomp.demon.co.uk http://www.jlcomp.demon.co.uk/faq/ind_faq.html The Co-operative Oracle Users' FAQ http://www.jlcomp.demon.co.uk/seminar.html Optimising Oracle Seminar - schedule updated May 1st ----- Original Message ----- From: <J.Velikanovs@xxxxxxxx> To: <oracle-l@xxxxxxxxxxxxx> Cc: <oracle-l@xxxxxxxxxxxxx>; <oracle-l-bounce@xxxxxxxxxxxxx> Sent: Wednesday, June 30, 2004 10:32 AM Subject: RE: Physics of the FILTER operation within SQL_PLANE. Lex, Thank for comment, I use RBO just for proof of concept. I am sure that the same situation can be emulated with CBO, but in this case it was easy for me to use RBO. >> about the optimizer not being able to calculate differences Even if would use CBO it will not be able to calculate difference in case of FILTER operation, was my point. Jurijs ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx put 'unsubscribe' in the subject line. -- Archives are at //www.freelists.org/archives/oracle-l/ FAQ is at //www.freelists.org/help/fom-serve/cache/1.html -----------------------------------------------------------------