Fw: impact of changing optimizer_features_enable

• Forwarded Message ---- From: Fuad Arshad <fuadar_at_yahoo.com> To: ujang.jaenudin_at_gmail.com Cc: oracle-l_at_freelist.org Sent: Saturday, June 23, 2007 9:25:27 AM Subject: Re: impact of changing optimizer_features_enable

if you have jonathan lewis' bookcost based optimizer . he devotes a whole chapter/appendix on this subject as to what changes. i am using this for my application. the good thing about 10.2 is that thisis a session level parameter so you can actually code a trigger. i'm on 9i and this is a system setting which disables all 9i features including system statistics etc.  you can actuially go and look at each _ parameter and tryot find which parameter might be the cause .or do a 10053 trace and see what parameters itis using with optimizer_features_enable=10.2 vs optimizer_features_enable=8.1.7 this will pretty much bringyou to the parameter changes internally and might lead you to a solution.

• Original Message ---- From: Ujang Jaenudin <ujang.jaenudin_at_gmail.com> To: oracle-l_at_freelists.org Sent: Friday, June 22, 2007 11:10:07 PM Subject: impact of changing optimizer_features_enable

all,

i have a funny things about how oracle given execution plan.

now my db is 10.2.0.3 on itanium 64bit.
when tried *.optimizer_features_enable from 10.2 until 9.2 , the report was not much different (so slow). but when change to *.optimizer_features_enable=8.1.7, it amazingly so so so fast....

so, does anyone have experiences about changing the above parameter and the impact to the applications?

thanks for your sharing...

--

regards
ujang
--

http://www.freelists.org/webpage/oracle-l
--

http://www.freelists.org/webpage/oracle-l Received on Sat Jun 23 2007 - 09:26:51 CDT