RE: rm RULE based optimizer != GOOD IDEA

  • From: "Marquez, Chris" <CMarquez@xxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Fri, 22 Apr 2005 10:27:19 -0400

I have not supported Oracle Apps, but from what I understand it is
loaded with hints and I believe some of the using "RULE hint.
Seems a little "Do as I say not as I do" from Oracle Corp....eh?

I agree about the spending all day on with stats and explain plans.
I have a script to look for blocking locks using v$ views...it ran ok,
but a DBA friend made if faster in about 5 minutes by adding a RULE
hint.
Maybe I should be going after the base Oracle tables, but I don't have
all day.

Finally about execution plans and speed changing of sql using the RBO.
If I'm not mistaken many environment changes can effect CBO too!?

Chris Marquez
Oracle DBA
HEYMONitor(tm) - heymonitor.com
"Oracle Monitoring & Alerting Solution"

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Post, Ethan
Sent: Friday, April 22, 2005 9:14 AM
To: Niall Litchfield
Cc: Michael Fontana; oracle-l@xxxxxxxxxxxxx
Subject: RE: rm RULE based optimizer !=3D GOOD IDEA


Well that would be a big leap.  However, I am not saying Oracle should
keep the RULE hint because one customer has one query which will benefit
from doing so.  I am assuming there are hundreds of queries such as this
that I will come across in my career and that can be multiplied of
1000's of DBA's elsewhere.

Yes you can achieve the same results without the hint but that may
require a lot of work and adding the hint does not.  I apologize for not
playing the part of the Oracle purist here but sometimes I just want to
get the job done and the RULE hint has worked very nicely for me and
others on this list numerous times in the past.

What if Oracle decides to drop other hints for indexes, join types
etc...?

-----Original Message-----
From: Niall Litchfield [mailto:niall.litchfield@xxxxxxxxx]=3D20
Sent: Friday, April 22, 2005 4:41 AM
To: Post, Ethan
Cc: Michael Fontana; oracle-l@xxxxxxxxxxxxx
Subject: Re: rm RULE based optimizer !=3D3D GOOD IDEA

It seems a big leap to me from "adding the RULE hint helps my one
query", to "we should keep the RBO", not least because you can achieve
the same effect without the RULE hint.


--=3D20
Niall Litchfield
Oracle DBA
http://www.niall.litchfield.dial.pipex.com

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